Displays

Sedimentary charcoal records typically provide information about variations in wildfire activity over thousands of years, and a few even span millions of years. Such long, continuous measurements of combustion products offer a rare opportunity to understand the response of fire to both rapid and gradual climate forcings, whether from human-caused global warming, volcanic activity, atmosphere-ocean circulation changes, or Milankovitch cycles. Here we use paleofire records from the Global Charcoal Database to demonstrate the dynamic nature of wildfire activity in response to varied forcings, particularly the role that relatively small temperature and precipitation shifts have on patterns of burning across space and time. Paleodata from areas currently experiencing severe wildfires are also examined in order to provide context for events that appear unprecedented in modern times.

How to cite: Marlon, J., Daniau, A.-L., Bartlein, P., and Rajaoberison, A.: What paleofire records can say about the present and future of fire on Earth, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22123, https://doi.org/10.5194/egusphere-egu2020-22123, 2020.

Fire as a hydrologic agent has been most frequently examined in terms of erosion and water quality, with studies on the ecohydrology expressed as evapotranspiration/streamflow often focussing on short term perturbation that relaxes with vegetation recovery. Far more dramatic ecohydrologic impacts are possible if repeated fire disturbance leads to species change. Such a scenario occurs in some forests in south-eastern Australia, a region that is among the most flammable in global terms due to the confluence of climatic and stand productivity factors. The most vulnerable of these forests are the “ash” type – mainly Eucalyptus regnans and E. delegatensis. The E.regnans ecology  has evolved with long fire intervals as medium/hot fire kill the trees, which then regenerate as single aged strands. However there have been several large short interval fire events in mountain forests (eg. 1926-1939, 2003-2006-2009-2019) in the past decades that overlap in area. E.regnans, and the other ash-type species, require 15-20 years to develop seed. If re-burnt, the stands cannot naturally regenerate. Frequently acacia and other understorey species colonise the sites, resulting in a dramatic change in forest structure and biomass.

The implications of this change are significant, with potentially high magnitude changes in ecohydrologic functioning. Further, these areas are the principal water supply catchments the city of Melbourne (> 4 M pop.) and a number of other towns. The impact of high frequency fire that is predicted to increase under climate change therefore has the potential to change ecology, hydrology and essential ecosystem services, in this case, water supply.

An extensive field experimentation and modelling program set out to (a) investigate the climatic conditions under which these wet forests burn and the sensitivity of these drivers to predicted climate change; and (b) evaluate the eco-hydrologic impact of a species change from E.regnans to acacia species over an age sequence of 80 years.

Results revealed there is an envelope of dry surface soil and maximum vapour pressure deficit (VPD) within which there is a 50% chance of uncontrolled fire. The most damaging fires occurred when VPD was within the upper 0.01% of values and available surface soil water below 55%. Modelling suggests this conjunction of drivers will increase significantly in the future.

Stand structure, particularly sapwood area, diverged between the eucalypts and acacias at age 10-20 years, with the difference increasing until acacia death at age 80. This structural parameter scales with ET, with acacias exhibiting a marked decline over time relative to E. regnans. This ET change is principally driven by sapwood area. These differences increase as the stands age, resulting in A.dealbata using around 30% of an E.regnans stand at age 80. This represents a fundamental change in eco-hydrology, and suggests a system pushed to a state of disequilibrium. The stand structural attributes over the age sequence indicate a large change in carbon stocks, resulting in significant alteration of both carbon and water cycles under this disturbance. The results have significant implications for water supply, forest ecosystem services, and system feedbacks of flammability-fire-ecohydrology.

How to cite: Lane, P., Benyon, R., Lakmali, S., Inbar, A., and Sheridan, G.: High frequency fire drives forest species change: impacts on ecohydrology and ecosystem functioning, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20587, https://doi.org/10.5194/egusphere-egu2020-20587, 2020.

Fire is one of the main drivers of forest loss worldwide and its role varies depending on natural and anthropogenic drivers, ranging from large boreal wildfires to smallholder shifting agriculture. The emergence of higher resolution satellite data creates new opportunities for studying the spatial and temporal relatedness of fires and forest loss. We have quantified this relatedness by overlapping global forest loss for 2001-2018 with fire detections from burned area and active fire satellite products at 500 m resolution. Previous studies have shown that global burned area is decreasing, mostly caused by increased human influence in savanna ecosystems. However, the opposite is true for forests: our study of trends and variability shows that forest loss has increased substantially over the last two decades in many parts of the world and that its dynamics are strongly linked to fire. Striking increases in forest loss were found for rapidly developing regions such as Africa and Southeast Asia, where commodity-driven deforestation and shifting agriculture have led to increased land clearing, often with the use of fire. Besides, stand-replacing wildfire activity has increased in boreal, temperate and tropical forests. The increase in fire activity in forests and decrease in savannas shows that the global balance is shifting because of both natural and anthropogenic factors, with important consequences for the future carbon cycle.

How to cite: van Wees, D. and van der Werf, G.: The contribution of fire to a global increase in forest loss, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18049, https://doi.org/10.5194/egusphere-egu2020-18049, 2020.

Fire regimes respond to both climate and human land management practice changes, in turn modifying land cover distributions, surface albedo, carbon storage, and emissions. Much attention has recently been given to the health and climate impacts of fires, but fires are also an important source of nutrients, such as iron and phosphorus, to both land and ocean biospheres. Fires therefore create important feedbacks within the Earth system. Here we discuss recent developments showing how fires are a previously underestimated source of limiting nutrients, providing up to half the annual deposited amount of soluble iron and soluble phosphorus to southern oceans and the Amazon, respectively. Fire can therefore stimulate ocean productivity by providing long range transport of essential nutrients, released from the vegetation burned and entrained with dust from the surrounding environment, to remote regions. We considered the impact of human activity on soluble iron deposition for the past (c.1750 CE), present (c.2010 CE), and future (c.2100 CE). We find that the global carbon cycle and climate response is dominated by changes to primary productivity within the Southern Ocean (>30ºS) and that the carbon export efficiency (gram of carbon sequestered per gram of soluble iron added) for this region is 43% larger when altering fire emissions compared to altering dust emissions. Results suggest that modelling past and future changes in biogeochemical cycles should incorporate information on how fires, and the nutrients carried within their plumes, respond to changes in climate.

How to cite: Hamilton, D., Barkley, A., Moore, J. K., Arneth, A., Bond, T., Carslaw, K., Gaston, C., Hantson, S., Ito, A., Kaplan, J., Lindsay, K., Nieradzik, L., Prospero, J., Rathod, S., Scanza, R., and Mahowald, N.: Underestimated Role of Fires in Providing Nutrients for Biogeochemical Cycles, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10650, https://doi.org/10.5194/egusphere-egu2020-10650, 2020.

Aerosols emitted from wildfires could significantly affect global climate through perturbing global radiation balance. In this study, Community Earth System Model with prescribed daily fire aerosol emissions is used to investigate fire aerosols’ impacts on global climate with emphasizing the role of climate feedbacks. The total global fire aerosol radiative effect (RE) is estimated to be -0.78±0.29 W m^-2, which is mostly from shortwave RE due to aerosol-cloud interactions (REaci, -0.70±0.20 W m^-2). The associated global-annual mean surface air temperature (SAT) change (∆T) is -0.64±0.16K with the largest reduction in the Arctic regions where the shortwave REaci is strong. Associated with the cooling, the Arctic sea ice is increased, which acts to re-amplify the Arctic cooling through a positive ice-albedo feedback. The fast response (irrelevant to ∆T) tends to decrease surface latent heat flux into atmosphere in the tropics to balance strong atmospheric fire black carbon absorption, which reduces the precipitation in the tropical land regions (southern Africa and South America). The climate feedback processes (associated with ∆T) lead to a significant surface latent heat flux reduction over global ocean areas, which could explain most (~80%) of the global precipitation reduction. The precipitation significantly decreases in deep tropical regions (5°N), but increases in Southern Hemisphere tropical ocean, which is associated with the southward shift of the Inter-Tropical Convergence Zone and the weakening of Southern Hemisphere Hadley cell. Such changes could partly compensate the interhemispheric temperature asymmetry induced by boreal-forest fire aerosol indirect effect, through intensifying the cross-equator atmospheric heat transport.

How to cite: Jiang, Y., Yang, X.-Q., and Liu, X.: Impacts of wildfire aerosols on global energy budget and climate: The role of climate feedbacks, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10180, https://doi.org/10.5194/egusphere-egu2020-10180, 2020.

Assessment of anthropogenic radiative forcing requires a robust understanding of the composition of the pre-industrial baseline atmosphere from which calculations are made

It is often assumed that fire activity and the associated aerosol emissions were lower in the pre-industrial period than in the present day. However, some lines of evidence suggest that fire activity may have halved since the pre-industrial period. 

Here we compare the simulated ratio of pre-industrial (c.1750CE and c.1850CE) to present-day black carbon surface concentrations in five ESMs (CNRM-ESM2-1, EC-Earth3, IPSL-CM6, NorESM1.2, UKESM1), using historical fire emissions from the Sixth Coupled Model Intercomparison Project (CMIP6), to the ratio in Northern Hemisphere ice-core records. 

We find that when forced with CMIP6 fire emissions all ESMs overestimate the present-day to pre-industrial black carbon ratio. This is consistent with previous studies and suggests that the contribution of fire to the composition of the pre-industrial atmosphere may be too low. If the contrast between the pre-industrial and present-day atmospheres in these models is too great, they are likely to overestimate the strength of the anthropogenic aerosol radiative forcing.  

We extend our analysis to include additional ESMs providing historical simulations for CMIP6, as included in the IPCC’s Sixth Assessment Report.

How to cite: Carslaw, K., Scott, C., Yoshioka, M., Hamilton, D., O’Connor, F., Folberth, G., Mulcahy, J., Dalvi, M., Balkanski, Y., Checa-Garcia, R., Olivie, D., Schulz, M., Michou, M., Nabat, P., Nieradzik, L., van Noije, T., and Bergman, T.: Re-assessment of pre-industrial fires in CMIP6 models and the implications for radiative forcing, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18190, https://doi.org/10.5194/egusphere-egu2020-18190, 2020.

Socio-economic development in low and middle-income countries has been accompanied by increased emissions of air pollutants such as nitrogen oxides (NO_x: nitrogen dioxide (NO₂) + nitric oxide (NO)), which affect human health.  In sub-Saharan Africa, fossil fuel combustion has nearly doubled since 2000.  At the same time, biomass burning—another important NO_x source—has declined in Africa’s northern biomass burning region, attributed to changes in climate and anthropogenic fire management associated with agricultural development. Here we use satellite observations of tropospheric NO₂ vertical column densities (VCDs) and burned area to identify NO₂ trends and drivers over Africa. Across the northern ecosystems where biomass burning occurs—home to over 350 million people—mean annual tropospheric NO₂ VCDs decreased by 4.5% from 2005 through 2017 during the biomass burning season of November through February. Reductions in burned area explained the majority of these change in NO₂ VCDs, but there were also weaker relationships between changes in NO₂ VCDs and fossil fuel emissions over parts of West Africa, which were stronger during rainy season. Over Africa’s biomass burning regions, NO₂ VCDs tended to decrease with increasing population density up to a threshold of approximately 180 people per km², suggesting that anthropogenic activity causes a net reduction in NO₂ emissions across roughly 90% of the continent’s biomass burning regions. In contrast to the widely-held perception that socio-economic development worsens air quality in low and middle-income nations, our results suggest that countries in Africa’s northern biomass burning region are following a different pathway, resulting in regional air quality benefits. However, these benefits may be lost with increasing fossil fuel use.

How to cite: Hickman, J., Andela, N., Ossohou, M., Galy-Lacaux, C., Tsigaridis, K., and Bauer, S.: Biomass burning decline causes large reductions in NO2 burden over north equatorial Africa in spite of growing fossil fuel use, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3750, https://doi.org/10.5194/egusphere-egu2020-3750, 2020.

The 2019/20 forest fires in eastern Australia burned over 5.8 million hectares of mainly temperate broadleaf forest between September 2019 and January 2020. This burned area figure is expected to rise over the remainder of the austral summer, but is already an order of magnitude larger than the mean annual burned area for Australian forest fires over the last 20 years, which is ~0.59 Mha per year. Here we show that this forest fire event is of a record-breaking scale, both nationally and globally, and was pre-conditioned by wide-spread prolonged drought and extreme heat.

We analysed global remotely sensed burned area data for 2000-2019 to estimate annual burned area fractions of all continental forest biomes. The annual burned area fraction, which is related to the length of fire intervals and other aspects of fire regimes, allows us to compare levels of fire activity across different forest biomes and continents.

Though very large fires occur in some forest biomes, such as the boreal forests of North-America and Asia, over the 20 years covered by our data set, annual burned area fractions have been very small (<0.03) for nearly all continental forest biomes including Australia’s temperate broadleaf forest biome. These findings provide a global historical reference for the interpretation of the scale of the 2019/20 eastern Australian mega forest fires.

With fire activity in all forest biomes strongly constrained by the moisture content of the fuels, explanations for the unconstrained burning of millions of hectares of temperate broadleaf forest in a single season must be sought in the extreme drought that has affected eastern Australia for the last two years. We use gridded daily soil moisture predictions for the continent to show how widespread and prolonged dryness set the stage for the unprecedented forest fire event of 2019/20.

How to cite: Boer, M., Resco De Dios, V., and Bradstock, R.: The 2019/20 eastern Australian mega forest fires - a global forest perspective, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15693, https://doi.org/10.5194/egusphere-egu2020-15693, 2020.

Extreme wildfire seasons are becoming the new normal in Canada, and satellite imagery is a useful way to map these fires as they grow across the vast, fire-prone regions of the country. However, single-date and single-sourced imagery of active fires often contain clouds, flares, smoke, and haze that can create challenges for monitoring  burned areas over time. To address this gap, we applied rapid and scalable methods for synthesizing information on fire progressions using freely available satellite imagery, novel image fusion algorithms, and cloud-based data processing platforms. We identified images from Landsat-7, -8, Sentinel-2, and MODIS (MCD64A1 burned-area dataset) for the 2017 and 2018 British Columbia fire seasons that intersect the buffered extents of Canadian wildfires as determined by Canadian National Fire Database. We classified each raw image individually using a standard burned-area classification protocol related to each data source. We used the Bayesian Updating of Land Cover Classifications (BULC) algorithm to create coherent time series from the single-date classifications of optical data sources in Google Earth Engine. From the BULC classification stack, we calculated within-year, intra-annual fire progression metrics to compare satellite-derived fire behaviours between the 2017 and 2018 fire seasons, both at the whole fire season and the individual fire level. End-of-season burned-area estimates corresponded with estimates derived from the National Burned Area Composite (NBAC) product that is generated retrospectively from best-available fire mapping approaches. Additionally, we compared the BULC time series with fire progression estimates from MCD64A1 burned-area dataset to evaluate the influence of spatial resolution on burned-area estimates. Information outputs from this research enable cross-validation of fire behaviour models for different fire seasons and comparison of fire progression metrics between historic fires and fire seasons in Canada. The approach presented can be used to provide rapid and reliable information about active wildland fire progressions to better understand fire growth and associated drivers.

How to cite: Crowley, M., Cardille, J., White, J., and Wulder, M.: Mapping and comparing wildfire progressions using freely available, multi-source satellite data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1586, https://doi.org/10.5194/egusphere-egu2020-1586, 2020.

We inter-compare four remotely sensed Fire Radiative Power (FRP) products, the polar-orbiter products derived from active fires detected using the Moderate Resolution Imaging Spectroradiometer data (MCD14ML) and VIIRS (VNP14ML and VNP14IMGML), and geostationary products derived from data collected by Meteosat’s Spinning Enhanced Visible and Infrared Imager (the LSA-SAF FRP-PIXEL product). We focus on seven years of data (January 2012 to December 2018), and using the ability of the geostationary product to capture the daily fire cycle we quantify for each polar-orbiter FRP product the proportion of daily fire energy release that they capture and that which they miss, and also identify the areas where their overpass times successfully capture the diurnal fire activity peak, and where they do not. In addition, by analysing frequency density (f-D) distributions of FRP at a 0.5° grid cell resolution we evaluate each products minimum FRP detection limit, which typically precludes detection of a proportion of the highly numerous but individually relatively small and/or low intensity fires. Results are summarized by biome type based on the ESA CCI Land Cover product. Our inter-comparison allows for the identification and quantification of some of the key non-fire effects causing FRP underestimation in satellite FRP products: pixel size, pixel area growth off-nadir, and the low temporal resolution of polar-orbiting sensors. Our results and the methodology developed herein should serve to evaluate and cross-calibrate FRP estimates obtained by the future Copernicus Climate Change Services (C3S) FRP products, which initially at least will be based only on SLSTR data collected by the Sentinel-3 satellite.

How to cite: Mota, B., Gobron, N., and Wooster, M.: Inter-comparison of four operational satellite Fire Radiative Power (FRP) products: A spatial and temporal consistency assessment. , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8385, https://doi.org/10.5194/egusphere-egu2020-8385, 2020.

How to cite: Scholten, R. and Veraverbeke, S.: Fires can overwinter in boreal forests of North America, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6013, https://doi.org/10.5194/egusphere-egu2020-6013, 2020.

Wildfire is a widespread natural disturbance and internal ecological process, critical in shaping ecosystem structure and function across scales. The Indo-China Peninsula and its surrounding areas is a global hotspot of fires initiated by natural and anthropogenic drives. Studies indicated that both the Indian Ocean monsoon and the Pacific Ocean monsoon significantly influence the climate in this region, and the precipitation seasonality regulated by monsoon is a critical driver of prevalent wildfires. However, the relative importance of the two monsoon systems on the terrestrial ecosystems in this region, specifically via their effects on vegetation burnings, has rarely been estimated. Yunnan Province in Southwest China comprises the northeast corner of this region, and shares the intensive impacts of the two monsoon systems in terms of the characteristics of climate and wildfire activity. The present study integrated multiple data sources of the forest fires during 2003~2015 in Yunnan, detected the spatial and interannual variations of the fire occurrence and burnt area, and related the fire activities with the dynamics of the Indian Ocean Monsoon (IOM) and West Pacific Ocean Monsoon (WPOM). The monthly time sequence analysis of the forest fire events in Yunnan Province showed that, a significant, synchronous teleconnection can be detected between the forest fire dynamics and Indian Ocean Warm Pool intensity, while an opposite temporal pace was revealed for the West Pacific Ocean Warm Pool. During the study period, IOM dominated the wildfire seasonality in Yunnan in eight years, in contrast to the dominance of WPOM in five years. A borderline can roughly divides Yunnan into the west and the east climatic regions, which were dominated by IOM and WPOM, respectively. Humidity and the forest area ratio were the dominant factors for the mean annual fire number and burnt area in the IOM affected region; but in the WPOM region, rural road density was the most important factor. It was suggested that the fire regime of the IOM region was climate-driven for fire number and fuel-driven for burnt area, while the fire regime was dominant with human activities in the WPOM region in Yunnan

How to cite: Shen, Z. and Ying, L.: The imprints of Indian Ocean Monsoon and West Pacific Monsoon on the spatial and temporal patterns of forest fires in Yunnan, Southwest China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6135, https://doi.org/10.5194/egusphere-egu2020-6135, 2020.

Terrestrial Arctic is a critical region for positive carbon-climate feedback because of the release of considerable organic carbon from the permafrost buried in the soil. Fires rapidly transfer carbon to the atmosphere. Thus, carbon release through boreal fires could considerably accelerate Arctic warming; however, boreal fire occurrence mechanisms and dynamics remain largely unknown. Here, we analyze fire activity and relevant large-scale atmospheric conditions over southeastern Siberia, which has the largest burned area fraction in the circumboreal and high-level carbon emissions due to high-density peatlands. It is found that the annual burned area increased when a positive Arctic Oscillation (AO) takes place in early months of the year, despite peak fire season occurring 1 to 2 months later. A local high-pressure system linked to the AO drives a high-temperature anomaly in late winter, causing premature snowmelt. This causes earlier ground surface exposure and drier ground in spring due to enhanced evaporation, promoting fire spreading. Recently, southeastern Siberia has experienced warming and snow retreat; therefore, southeastern Siberia requires appropriate fire management strategies to prevent massive carbon release and accelerated global warming.

How to cite: Kim, J.-S., Kug, J.-S., Jeong, S.-J., Park, H., and Schaepman-Strub, G.: Extensive fires in southeastern Siberian permafrost linked to preceding Arctic Oscillation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6502, https://doi.org/10.5194/egusphere-egu2020-6502, 2020.

Fire is an important disturbance process, having significant socio-economic consequences on the one hand, while fulfilling a vital ecological role on the other. Across fire-prone ecosystems, different fire regimes can be found, reflecting a combination of climatic factors and of different plant species characteristics. Ecosystem flammability and fuel load are the most evident and well-studied aspects of fire regime, with only recently attention being devoted to plant traits associated with fire adaptation and post-fire response. The aim of this research is to understand the role that plant traits have in driving fire regimes in different fire-prone ecosystems across the world. A mathematical, mechanistic model was developed representing vegetation dynamics, including stochastic fires and different plant fire-responses. We observe that differences in combinations of plant traits are an important factor in determining alternative ecological states. This is driven by differences in how plants determine fire occurrence and in relation to competition between plant species. Differing plant communities under the same climatic conditions can occur when the most competitive plant types do not have a strong resistance to fires, leading to different ecological and fire regime states for example in some tropical savannas and forests, or in Boreal forests. Conversely, when the dominant plant type has a very strong, post-fire response (at individual level), as e.g. in Mediterranean forests, only one ecological state is possible. This research can help improving understanding of changes in fire regime in the future to assist in fire management efforts, and underlines the importance of including plant fire-responses when modelling fire ecosystems under climate-change scenarios.

How to cite: Baudena, M., Diaz-Sierra, R., Provenzale, A., Sweeney, L., and Magnani, M.: The role of plant traits in shaping fire regimes in different ecosystems across the world, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13840, https://doi.org/10.5194/egusphere-egu2020-13840, 2020.

Biomass burning is an important component of major biomes as it acts as an ecological forcing factor in controlling the vegetation composition as well as biomass production. Thus long-term paleo-fire records are required to understand the extent to which future fire regimes will affect ecosystem health and the global carbon balance. Unfortunately, paleo-fire proxies such as charcoal analysis, dendrochronology and archaeological relicts are often fragmented and difficult to interpret owing to their poor preservation in the natural archives. To resolve the uncertainties associated with the existing paleo-fire proxies, biomarker-based investigations (n-alkanes) provide a new avenue for gaining insight into the paleo-fire events due to their relatively stable chemical property and source-specific distribution in sediments. For instance, laboratory and field-based experiments have shown that a significant amount of short-chain n-alkanes (predominantly C₁₈) are produced at the expense of long-chain n-alkanes during thermal degradation of plant-derived organic matter. This modification of primary carbon chain-length can thus be used as a tool to decipher paleo-fire events. However, this characteristic distribution pattern of n-alkane in the soil can also result from microbial degradation of plant-derived organic matter. Therefore, it is vital to disentangle the effect of thermal and microbial degradation on the distribution pattern of n-alkane before using it for paleo-fire reconstructions. For this purpose, published n-alkane distribution records from two distinct climatic settings have been compared. The site-A is located in arid Banni grassland, western India (with a history of repeated fire events) whereas, site-B is situated at the sub-humid region of southern peninsular India (Lake Ennamangalam). The n-alkane distribution in both the sites exhibits a dominance of short-chain homologues with prominent even-over-odd preference (EOP). The cross-plot between the relative concentration of C₁₈ (dominant in short-chain) and C₂₉ (dominant in long-chain) homologues shows positive and significant correlation (R² = 0.9, p < 0.05, n=19) at site-A, whereas statistically insignificant correlation (R² = 0.2, p < 0.05, n=19) has been obtained from site-B. In case of thermal events, production of short-chain n-alkanes (predominantly C₁₈) is related to the temperature-dependent breakdown of long-chain n-alkanes. Subsequently, the concentration of C₁₈ and C₂₉ homologues are expected to be well correlated, as observed in site-A. On the contrary, in a depositional setting dominated by microbial activity, multiple sources of C₁₈ homologue may produce an insignificant correlation, as observed from site-B. Therefore, it can be suggested that short-chain n-alkanes at site-A are a product of thermal degradation while microbial activity controlled the distribution of short-chain n-alkanes at site-B. This claim is further supported by the ratio between the relative concentration of C₁₈ and C₁₉ homologues (P_Factor) which are much higher at site-A (11 to 62) compared to that of the site-B (1 to 10). Higher production of C₁₈ homologue during thermal degradation perhaps is producing the offset in the P_Factor values for site-A and B. Our observations will be useful to recognise paleo-fire events that have been previously overlooked owing to the fragmentary nature and limited preservation of existing proxies.

How to cite: Sarangi, V., Basu, S., and Sanyal, P.: Disentangling the effect of thermal and microbial degradation on the distribution pattern of n-alkanes in sediments: Implication for paleo-fire studies, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-387, https://doi.org/10.5194/egusphere-egu2020-387, 2020.

Fire disturbance appears to be one of the vital processes in shaping vegetation composition and landscape dynamics of an area. It is an essential driver of ecosystem structure, in close association with environmental conditions. Environmental factors, as well as human, can equally induce the fire at the stand. Untying the natural vs. anthropogenic factors is important to comprehend the paleoclimatic conditions at a regional and global scale. Therefore, identifying the fire events from chronologically well-constrained archaeological sites would provide an ideal opportunity to decode its cause and impact on the terrestrial environment. Hence, the present study is conducted on the fluvial cliff sections, which preserved the tools and artefacts from Lower Paleolithic (~100 ka) to Neolithic (~3 ka) phases in the Belan valley, north-central India.

In this study, paleosols samples (n=49) were collected from six sedimentary sections of archaeological sites. Paleosols were analysed for n-alkane distribution pattern, n-alkane ratio (C₁₆/C₂₉ and C₁₆/C₃₁), δD_n-alkane values, δ¹³C_n-alkane values and macro-charcoal (CHAR) to reconstruct the vegetation, climate and fire events. The n-alkane (C₁₅ to C₃₅) distribution signature, average chain length (ACL_15-33) and carbon preference index (CPI_25-33) values are used to distinguish the aquatic vs. terrestrial contribution in the organic matter (OM). The higher CPI_25-33 and ACL_15-33 values suggest terrestrial plants derived OM dominance in the paleosols. Four samples with lower CPI_25-33 (~1.0) and ACL_15-33 (~23.0) suggests higher degradation of OM. Moreover, the lower CPI_25-33 samples also showed a dominance of short-chain even-numbered alkanes (maximum at C₁₆ or C₁₈). A similar observation in short-chain n-alkanes was reported from the archaeological site with known fire events (Eckmeier and Wiesenberg, 2009). Also, the CHAR analyses (n=40) suggests that the degraded paleosols (lower CPI and ACL) have suffered thermal alteration. The CHAR and n-alkane ratio suggest paleofire events in the Belan valley during i) ~100 to 95 ka, ii) ~60 to 55 ka, iii) ~42 to 37 ka, iv) ~26 to 20 ka and v) ~8 to 3 ka. δD_n-alkane values suggested lower rainfall conditions during Large Glacial Maximum (LGM; ~25 to 18 ka). The intensification in rainfall observed during i) ~100 to 75 ka and iii) ~18 to 3 ka, which also corresponds to some fire events. The δ¹³C_n-alkane values suggest the dominance of grassland during LGM, which was favourable for wildfires. Further, the fire event during ~26 to 20 ka identified at Main Belan temporarily overlays with Mahagara and Koldihwa site. The lack of any significant signature of thermal degradation of paleosols (supported by n-alkanes) in Koldihwa and Mahagara suggests the extra-local nature of the fire. The higher rainfall is an unfavourable condition for natural wildfires. Further, the fire disturbance increases in the early-Holocene, which overlaps with the timing of high rainfall condition and agricultural activity in the Belan valley. Therefore, this study postulates that the prehistoric humans-induced fire from ~60 ka onwards.

Eckmeier, E. and Wiesenberg, G.L., 2009. Short-chain n-alkanes (C16–20) in ancient soil are useful molecular markers for prehistoric biomass burning. Journal of Archaeological Science, 36(7), 1590-1596.

How to cite: Jha, D. K., Samrat, R., and Sanyal, P.: First evidence of prehistoric humans-induced fire in India: clues from macro-charcoal, biomarkers distribution and compound-specific stable isotopes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-788, https://doi.org/10.5194/egusphere-egu2020-788, 2020.

Recent large-scale fire events in Siberia have drawn increased attention to boreal forest fire history. Boreal forests contain about 25% of all global biomass and act as an enormous carbon storage. Fire events are important ecological disturbances connected to the overarching environmental changes that face the Arctic and Subarctic, like vegetation dynamics, permafrost degradation, changes in soil nutrient cycling and global warming, and act as the dominant driver behind boreal forest’s landscape carbon balance. By looking into past fire regimes we can learn about fire frequency and potential linkages to other environmental factors, e.g. fuel types, reconstructed temperature/humidity or geomorphologic landscape dynamics. Unfortunately, fire history data is still very sparse in large parts of Siberia, a region strongly influenced by climate change. The Global Charcoal Database (www.paleofire.org) lists only a handful of continuous charcoal records for all of Siberia, with only three of those featuring published data from macroscopic charcoal as opposed to microscopic charcoal from pollen slides.

We aim to reconstruct the late Holocene fire history using lacustrine sediments of Lake Khamra (SW Yakutia at N 59.99°, E 112.98°). It covers an area of c. 4.6 km² with about 22 m maximum water depth, located within the zone of transition from summer-green and larch-dominated to evergreen boreal forest. We present the first continuous, high-resolution (c. 10 years/sample) macroscopic charcoal record (> 150 μm) including information on particle size and morphology for the past c. 2200 years. We compare this to complementary information from microscopic charcoal in pollen slides, a pollen and non-pollen palynomorph record as well as μXRF data. This multi-proxy approach adds valuable data about fire activity in the region and allows a comparison of different prevalent fire reconstruction methods. As the first record of its kind from Siberia, it provides a long-term context for current fire activity in central Siberian boreal forests and enables a better understanding of the environmental interactions occurring in the changing subarctic landscape.

How to cite: Glückler, R., Herzschuh, U., Pestryakova, L., Kruse, S., Vyse, S., Andreev, A., and Dietze, E.: Late Holocene fire history documented at Lake Khamra, SW Yakutia (Eastern Siberia) , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1018, https://doi.org/10.5194/egusphere-egu2020-1018, 2020.

Pyrogenic carbon (pyC) or fire-derived organic C (e.g., charcoal and soot), while generally considered stable in soils and sediments, can leach into pore waters forming dissolved pyrogenic organic carbon (pyDOC). This pyDOC may be exported to the ocean (about 10% riverine DOC may be pyrogenic). Yet, the processes which control this export and how pyrogenic dissolved organic matter (pyDOM) lability is related to its chemical composition are poorly understood. Thus, pyDOM was leached from a thermal series of oak and grass chars (250-650 °C) and photoirradiated in a solar simulator. About 10-20% of oak char leachate pyDOC was mineralized over five days, with greater proportions lost from leachates of higher temperature parent chars. Proton NMR revealed decreased relative amounts of aryl-C and increased low molecular weight C1 and alkyl-C components during the photo-incubation. Quantification of benzenepolycarboxylic acid (BPCA), molecular markers for condensed aromatic carbon (ConAC), indicated that 75-94% of ConAC was lost during the first five days of photoincubation, the majority of which occurred within the first 2 days, with a preference toward loss of ConAC of larger cluster sizes. Over 96-day microbial incubations, 37 to 48% of pyDOC was lost with modelled half-lives of about 13 days. Much of this was low molecular weight C1 compounds, while only 1 to 2% of ConAC was lost, with a preference for losses of smaller cluster size ConAC. Slightly greater proportions of both total pyC and ConAC was lost from pre-photodegraded pyDOM leachates. These results highlight the large portion of pyDOM that is potentially remineralized or transformed in aquatic systems at short timescales, and the need to examine both condensed and non-condensed portions of pyDOM to understand the effects of fires on aquatic biogeochemistry.

How to cite: Zimmerman, A. R., Bostick, K., Goranov, A., Mitra, S., Hatcher, P., and Wozniak, A.: Photo- and Biolability of Pyrogenic Dissolved Organic Matter: A Laboratory study of Thermal Series of Laboratory-Prepared Char Leachates, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1593, https://doi.org/10.5194/egusphere-egu2020-1593, 2020.

Fire is an important environmental and ecological process in northern high latitude environments. It is currently unclear how fire regimes will change in response to current environmental change in this region and the implications this may have for ecosystem processes and human societies. We reconstruct changes in biomass burning since the Last Glacial Maximum in the northern extratropics (>45°N), using data from the Global Charcoal Database complemented by new records from Canada, Beringia and Russia. A clustering machine-learning algorithm (K-means) is used to delimit regions that show similar burning histories. Comparison of the regional trajectories of change in biomass burning provides insights into the environmental drivers of fire. Generalised linear modelling is then used to explore the independent roles of climate, vegetation changes and human activities on changes in fire regimes for each region and for the northern extratropics as a whole. This study provides quantitive information about the differential importance of the drivers of changes in fire regimes in different regions and at different timescales since the Last Glacial Maximum, and provides insights about how these may influence future fire regimes across this region.

How to cite: Kesner, D., Harrison, S., Blyakharchuk, T., Edwards, M., Garneau, M., Magnan, G., and Prentice, C.: Spatial variability in biomass burning in the northern extratropics since the Last Glacial Maximum, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2730, https://doi.org/10.5194/egusphere-egu2020-2730, 2020.

Forest fires are an important factor of the global carbon cycle and high latitude ecosystems. Eastern Siberian tundra, summergreen larch-dominated boreal forest on permafrost and evergreen spruce- and pine-dominated boreal forest have characteristic fire regimes with varying fire frequencies and intensities. However, it is unknown which role fire plays in climate-vegetation-permafrost feedbacks and how high-latitude fire regimes and ecosystems will change in a warmer world – questions that are crucial considering that boreal and permafrost regions have been identified as tipping elements in the climate system (Lenton et al., 2008, PNAS).

Here, we investigate fire regime shifts during previous warmer-than-present interglacials, i.e. marine isotope stages (MIS) 5e and 11c, which were not influenced by human activity. We use specific biomass burning residues, i.e. monosaccharide anhydrides (anhydrosugars), that are a rather chemically reactive group of pyrogenic carbon. These molecules are mainly produced by low-temperature fires, but their pathways through the Earth system from source to sink and their stability in sedimentary deposits are very poorly constrained (Suciu et al. 2019, Biogeochemistry). A recent study (Dietze et al., 2020, ClimPastDisc) found anhydrosugars in up to 420 kyr old sediment of Lake El’gygytgyn (ICDP Site 5011-1), northeastern Siberia, and suggest that these molecular markers are suitable proxies for fires in Siberian summergreen boreal forests. Surprisingly, the ratios of the anhydrosugars levoglucosan to its isomers mannosan and galactosan were exceptionally low compared to published emission ratios from modern biomass burning, pointing to either a specific local biomass source and/or isomer-specific preservation.

To understand what anhydrosugars from interglacial Arctic lake sediments tell us about fire regime changes, we studied modern sediment samples from Lake El’gygytgyn, its catchment and from other lakes located in East Siberian summergreen and evergreen boreal forest. The latter lake systems represent spatial analogues to the conditions at Lake El’gygytgyn during MIS 5e and 11c, respectively. We analyzed anhydrosugars using ultra high-performance liquid chromatography coupled to a high-resolution mass spectrometer. We discuss the modern anhydrosugar concentrations and isomer ratios in context of (1) well-explored modern lake and catchment configurations and (2) multiple late glacial to interglacial results of Lake El’gygytgyn sediment cores. By better constraining the sources and (degradation) pathways that determine the proxy meaning of sedimentary anhydrosugars in northeastern Siberia, we provide a step forward to understand the regional pyrogenic carbon cycle and long-term feedbacks that are crucial for model predictions of future fire regime shifts in the high northern latitudes.

How to cite: Dietze, E., Mangelsdorf, K., Andreev, A., Schwamborn, G., Melles, M., Wennrich, V., Fedorov, G., Vyse, S., and Herzschuh, U.: What do anhydrosugars in up to 420 kyrs old Lake El’gygytgyn sediments tell us about low-temperature fires of northeastern Siberia?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8019, https://doi.org/10.5194/egusphere-egu2020-8019, 2020.

The fires themselves have become important factor, which controls ecosystems, pedological processes and climate.

Our work are aimed as the decoding of the soil archives, which contain unique information about the direction and rates of the soil formation; the interactions between fire and vegetation composition and studying the long-term dynamics of vegetation.

The primary study objects are charcoal layers in pyrogenic soils, preserved in particular geomorphological traps of various karst landscapes in the North part of European Russia. Such layers, as pyrogenic archives are represented by several (up to dozens)  interlayers, that are separated by buried soil profiles.

The main method is pedoanthracological. About 100 charcoal particles from all interlayers in different podzol soils were studied. The age interval was between early Holocene and modern time.

Results. The bulk of all coals was represented by pine, the rest by spruce. Coals belonging to other tree species (for example, birch) were absent. That is, only indigenous coniferous forest always burned.

Conclusions. Over the entire period of soil and sediment formation, the vegetation cover in the region has not changed. It is possible that the time period required to restore indigenous forests and the chronology of the cyclicality of fires are interconnected.

The study was supported by the Russian Foundation for Basic Research. Project No. 19-23-05238.

How to cite: Golyeva, A. and Petrov, D.: Charcoals as archives of soils pyrogenic events, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11726, https://doi.org/10.5194/egusphere-egu2020-11726, 2020.

Fire is an intrinsic feature of terrestrial ecosystem, and a key Earth system process that strongly affects ecosystem structure and functioning , carbon and nutrient cycles, climate, air quality and society. Although local and regional paleo-fires in China have been investigated based on one or several fire-proxy records, so far China’s fire history at the country level and its driving forces remain unknown. The present study, for the first time, reconstructs China’s fire history based on charcoal and black carbon records at 107 sites through the Holocene (12 ka BP to the present in this study), and investigates fire historical changes and dominant drivers. Results show that fire activity over China gradually decline from the Early Holocene (12 ka BP) to the Middle Holocene (7.3 ka BP), followed by a sharp rise till the present age. The historical changes are mainly regulated by moisture change through the whole Holocene, and also affected by population growth and agriculture expansion over the past 2 ka.

How to cite: Xu, X., Li, F., Lin, Z., and Song, X.: Fire history in China during the Holocene and its response to the changes in environmental and anthropogenic factors, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7697, https://doi.org/10.5194/egusphere-egu2020-7697, 2020.

The relationship between Holocene changes in Fennoscandia biomass burning (reconstructed by means of sedimentary charcoal records from lake and peat bogs) and main forest composition (based on pollen reconstructions from the same sites) divided into three different fire sensitivity classes is explored based on the hypothesis that fire-prone species are more abundant during periods characterized by higher fire disturbance, while fire-intolerant species dominate when biomass burning is low.

The overall patterns found across Fennoscandia suggest that there was low but increasing fire activity during the early Holocene, while a low and decreasing trend characterized the middle Holocene. During the late Holocene biomass burning increased, with a peak around 500 cal yr BP. This maximum is then followed by a downturn during the last centuries.

Generally, fire-prone species are strongly positively correlated with multi-millennial variability of biomass burning in Fennoscandia forests. A positive - but much weaker - relationship also exists between fire-tolerant species and long-term fire trends. On the contrary, a quite strong negative correlation is detected between biomass burning and fire-intolerant species.

The results presented in this large-scale analysis demonstrate that biomass burning was highly linked to fuel type (according to different fire sensitivity classes) during the Holocene, underlying the fact that all past fire-climate studies must consider key functional interactions between fuel type and long-term changes in fire regime.

How to cite: Molinari, C., Bradshaw, R. H. W., Carcaillet, C., Hannon, G., and Lehsten, V.: Role of vegetation on fire behaviour in Fennoscandia forests during the Holocene, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2914, https://doi.org/10.5194/egusphere-egu2020-2914, 2020.

The spontaneous combustion risk of Jurassic coal in Northwest China is special and different from that of permo-carboniferous coal. TG-FTIR experiments of a typical Jurassic coal sample in north Shaanxi was carried out to identify the grading, gas graduating and oxidation kinetics characteristic, under four heating rates of 5, 10, 15, and 20 ℃·min^–1 in an air atmosphere. The coal oxidation process of Jurassic coal at low temperature could be divided into two stages, mass loss stage and mass gain stage. The changing rules of apparent activation energy in the coal oxidation process at low temperature were determined by FWO and Kissinger methods. The model-fitting mathematical approach was used to identify the reaction kinetics mechanism functions at two oxidation stages of Jurassic coal in northwest China.

How to cite: Wang, K., Fan, H., He, Y., Deng, J., and Zhang, Y.: Oxidation kinetics of Jurassic coal in Northwest China at low temperature by TG and FTIR analysis, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8938, https://doi.org/10.5194/egusphere-egu2020-8938, 2020.

Grasslands provide critical ecosystem functions and services globally, including forage production for livestock and other animals. As frequency and intensity of disturbances, including fire and drought, are increasing globally, grasslands and the services they provide are particularly vulnerable. In this changing environment, resistance, the capacity to withstand disturbance, and resilience, the capability to recover from disturbance, are important for the stability of grassland ecosystems during and after extreme climate events. Quantifying how grazed grassland’s resistance and resilience respond to these disturbances provides important information of stability of grassland function under forecast climate change.

In this study, we focus on fire experiments in grasslands located in the Kruger National Park in South Africa (tropical savanna grassland) and the Konza Prairie Biological Station in the US (mesic temperate grassland). Both sites experienced extreme drought (SPEI <-2) this past decade, in 2015 and 2012, respectively. Further, both sites have long-term fire frequency treatments (annually burned, burned every 3-4 years and unburned) that are grazed by large native herbivores (~14 species at Kruger and bison at Konza), which allows us to explore influences of fire frequency on grazed grassland’s resistance and resilience to extreme drought. Using Landsat remote sensing data, we generated 30 m x 30 m NDVI monthly time series for each fire frequency treatment and conducted repeated measures ANOVA to compare the vegetation productivity two years before, during, and two years after the extreme one-year drought events.

Although large reductions in productivity occurred during the extreme drought at both sites and across the grazed fire frequency treatments, full recovery of production was observed the following year, consistent with trends observed in ungrazed grasslands at the study sites. These results suggest that grazed grasslands show high resilience, but low resistance to extreme drought. However, the degree of resistance and resilience was influenced by fire frequency. At Konza, during and after extreme drought in 2012, unburned grassland showed the lowest resistance but higher resilience, while grassland burned every four years and annually had higher resistance but relatively lower resilience. The anomaly of NDVI at Kruger exhibited an opposite pattern. These differences in resistance and resilience of production to extreme drought across the fire frequency treatments are likely due to changes in species composition or ecosystem structure (i.e., increased density of woody species in the absence of fire). Ultimately, these results suggest that fire frequency plays an important role in grazed grassland ecosystems’ vulnerability to extreme drought.

How to cite: Li, X., Hajek, O., LaRoe, J., Wilkins, K., Knapp, A., and Smith, M. D.: Fire frequency influenced grazed grasslands' resistance and resilience to extreme drought, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12758, https://doi.org/10.5194/egusphere-egu2020-12758, 2020.

Prescribed burning is a management tool used in the last years to prevent the invasion of woody vegetation in pastureland, decreasing the risk of extensive wildfires in vulnerable areas. Nevertheless, the effect of this practice in the soil is not yet fully understood, and more information is needed to ameliorate management practices. In order to understand how prescribed fire affect soil fertility, and the carbon (C) and nitrogen (N) cycles in pastures invaded by shrubs in Mediterranean areas, we carried out an experiment in Montseny, an acidic pre-littoral mountain range northern Barcelona (NE Iberian Peninsula). This area has experienced a decrease in traditional sheep stocks and therefore pastures endure strong shrub encroachment. We wanted to know: 1) what are the effects of prescribed burning on soil fertility in acidic Mediterranean pastures? and 2) are there legacy effects of the previous vegetation patches on the soil C and N cycles after prescribed burning? To answer those questions, we sampled soils before and after prescribed burning of a pasture heavily invaded by shrubs. Soils were sampled under six canopy types: Erica scoparia-dominated patches, Calluna vulgaris-dominated patches, Cytisus scoparius-dominated patches, Pteridium aquilinum-dominated patches and Cladonia-dominated biological crusts. The exact soil sampling point was recorded by a highly precise GPS, and each point resampled few days and six months after burning. As expected, soil fertility parameters varied with burning, including losses in soil phosphorus and nitrogen. In addition, several soil C and N parameters responded to the previous vegetation patches, including shifts in soil C and N concentration.

How to cite: Manjón-Cabeza, J., Ibáñez, M., Rodríguez, A., Broncano, M. J., Plaixats, J., and Sebastià, M. T.: Effects of prescribed burning on soil fertility and carbon dynamics in pre-littoral Mediterranean mountain pastures, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20289, https://doi.org/10.5194/egusphere-egu2020-20289, 2020.

In fire-prone ecosystems subjected to frequent fires, trees species with different post-fire regeneration strategies (PFRS) coexist at local scale. Different growth dynamics and habitat selection of species account for their coexistence. To explore how much variety is decided by the PFRS, we selected four co-occurring tree species including one Facultative seeders (FS) species and three obligate resprouters (OR) species, conducted a field investigation to measure growth dynamics at sites with different time since last fire (TSF) and recorded its living environment information in Central Yunnan Plateau. We also measured the burl size of OR species to subclassify PFRS into obligate resprouters-resprouts number (OR-N) and obligate resprouters-resprouts height (OR-H) by the growth priority to quantity or height. Generally, FS and OR species exhibited different seedlings clump density and height growth rate (HGR) and showed different temporal dynamics. OR-N species occupied post-fire gaps with rapid canopy growth and were more predominant than OR-H species and FS species at the early period of post-fire regeneration, while OR-H species had the highest HGR. However, such difference was not well explained by environmental factors (R² < 20%) except seedlings growth rate, while explanation increased when subclassfication was considered as random factor in linear mixed models (LMMs). Moreover, species habitat selection was also associated tightly with regeneration strategies. The result of Redundancy Analysis (RDA) indicated that Pinus (FS) dominated on sunny slope was consistent with gap-dependence model and environment-variability model, and Cyclobalanopsi (OR-H) are favored in the fertile sites that can facilitate its height growth. Resprouters species Lithocarpus which prefer growing on sunny slope in unburned areas but showed preference on shade slope in post-fire regeneration. Therefore, the impacts of regeneration strategies caused some species shift their normal distribution ranges after fire. In conclusion, different growth dynamics and habitat selection of the four tree species during the post-fire regeneration enable their coexistence. Our study provides a novel perspective that by using subclassification of regeneration strategies, the prediction power of species performance and niche partitioning can significantly increased.

How to cite: Luo, C., Li, Y., Yang, K., Han, J., Jiang, Y., and Shen, Z.: Post-fire regeneration strategies contribute to plant growth dynamics and habitat selection in subtropical monsoon fire-prone ecosystem, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6490, https://doi.org/10.5194/egusphere-egu2020-6490, 2020.

Fire has an important impact on the terrestrial carbon cycle, affecting the growth and distribution of vegetation, and altering carbon stores in vegetation and soils. This is further complicated by the interaction with people, through land-use change, ignitions and fire management. This work presents the latest results from the recently coupled JULES-INFERNO fire enabled land surface model, and the interaction of fire, dynamic vegetation and varying land use. The results of historical and present-day global simulations are evaluated using observations of burned area and emissions, and through use of tools such as ilamb. The model performs well globally compared to observations, and improves the simulation of vegetation especially in the tropics. The model is also used to address how fire may change under different climate scenarios, including El Niño events, and future simulations of climate change. Results show that burned area increases in some areas with El Niño conditions such as those of 2015/16, especially in South America where a 13% increase in burned area and emitted carbon is simulated. This negatively impacts carbon uptake in this region, and reduces the terrestrial carbon sink.

How to cite: Burton, C., Betts, R., Jones, C., and Kelley, D.: Fire-vegetation feedbacks in JULES-INFERNO, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18380, https://doi.org/10.5194/egusphere-egu2020-18380, 2020.

Vegetation build up is a major controlling factor for wildfires globally. The exact nature of the dependency of wildfire activity on past vegetation productivity is still under debate, however. Given the potential future rise in conditions conducive to extremely damaging fires in many regions of the world, controlling factors like this need to be investigated urgently to better understand and manage especially extreme wildfire events.
To improve our understanding of wildfires and the advice given to policy makers, a comprehensive understanding of all contributing factors is required. Changes to land management can be controversial and thus concrete evidence is required to assess and modify longstanding management practices and regulations if needed.
We therefore used global satellite datasets extending from 2005 to 2011 to assess the relationship between burnt area and various biophysical variables. Vegetation proxy data included vegetation optical depth and the fraction of absorbed photosynthetically activate radiation. Different regions and time periods were analysed separately to isolate regional and temporal effects respectively. The relationship between pre-season vegetation productivity and burnt area was modelled as a regionally and temporally varying weighted sum of past monthly productivity proxies.
As expected, significant differences in fire regimes were found across biomes, signified for example by significant shifts in the seasonality of burnt area. Understanding these shifts in the seasonality of both burnt area and the accompanying temporal dependence on past vegetation growth is key to reproducing observed wildfire regimes in fire models. As these relationships were found to vary both temporally and regionally, judicious inclusion of biophysical variables in fire models coupled with algorithms able to capture these relationships is necessary. 
However, remotely sensed observations were of different quality in different areas due to inhomogeneous cloud cover patterns, making assessments for much-affected regions like South America and South East Asia especially difficult. Likewise, the found correlation between decreasing cloud cover and increasing burnt area biased our results. Due also to the short time span of the data available in this investigation, these factors warrant further investigation to more fully quantify the temporal and regional relationships at work.

How to cite: Kuhn-Regnier, A., Voulgarakis, A., Harrison, S., and Prentice, C.: The Importance of Vegetation Build Up for Burnt Area Seasonality, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16359, https://doi.org/10.5194/egusphere-egu2020-16359, 2020.

A series of fire events have captured the attention of the public and press in the last couple of years. South America, for example, saw the largest increase in fire count in nearly 10 years, mainly in areas historically associated with deforestation in Amazonia. Meanwhile, South Eastern Australia has seen a number of devastating bush fires in recent months, resulting in (at time of writing) 27 deaths and the destruction of over 2000 properties. These two fire events, in particular, have sparked debates about whether the levels of burning were unprecedented, and if so, whether they were driven by changes in human ignitions or land management, or if the fire season was drier than normal and whether climate change played a role. However, confidently determining the main drivers of fire events such as these often remains challenging. There is an ever-increasing availability of near-real-time meteorological and fire activity data that could be used to determine drivers, but the complex interplay of different fire controls makes teasing apart drivers of fire difficult from observations alone. Many coarse-scale fire-enabled terrestrial biosphere models account for some interplay of controls. However, most fail to reliably reproduce trends in fire, and often rely on inputs that are not available for some time after these fire seasons have passed.

Here, we have developed a Bayesian framework which addresses this by inferring fire drivers directly from observations and tracking uncertainty in a simple fire model. The model uses coarse resolution, monthly data that is available at near-real-time and emulates most fire-enabled land surface schemes by summarizing drivers as controls describing fuel continuity; moisture; lightning and human ignitions; and human suppression. The framework can be trained on different fire-related variables and finds a posterior probability distribution of both the model parameters and the expected fire activity from the model as a whole. This allows us to determine the probability of a particular fire season event within the context of the historical meteorological record, as well as the main drivers of unusual fire events.

This framework is first applied globally, identifying tropical forests and woodland ecosystems as key hotspots of long term fire regime shifts. In South Eastern Australian woodland, changes in fuel continuity and moisture point to a weak, long term decline in fire activity, but with increased variability, indicating a higher probability of extreme fire years. The arc of deforestation in the Amazon shows long-term increased susceptibility to fire due to drying conditions from changes in land cover. However, when focusing the framework specifically on Amazonia, we show lower meteorologically driven fire counts than we see in the observations for 2019, and that it is extremely likely (>95% probability) that the weather conditions have not triggered the very high levels of fire seen in the Amazon this last year. This demonstrates the potential of the framework for use in rapid attribution of drivers in future extreme fire seasons.

How to cite: Kelley, D. I., Burton, C., Whitley, R., Huntingford, C., Bistinas, I., Brown, M., Dong, N., and Marthews, T. R.: Unusual fire seasons in a changing climate - A Bayesian approach., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19112, https://doi.org/10.5194/egusphere-egu2020-19112, 2020.

Wildfires are common in boreal forests around the world and strongly affect regional ecosystem processes and global carbon cycle. Previous studies have suggested that local climate is a dominant driver of boreal fires. However, the impacts of large-scale atmospheric teleconnection patterns on boreal fires and related physical processes remain largely unclear. This study investigates the influence of nine leading atmospheric teleconnection modes and El Niño-Southern Oscillation (ENSO) on the interannual variability of simultaneous summer fires in the boreal regions based on 1997-2015 GFED4s burned area, NCEP/NCAR atmospheric reanalysis, and HadISST sea surface temperature. Results show that ENSO has only a weak effect on boreal fires, distinct from its robust influence on the tropical fires. Instead, the interannual variability of burned area in the boreal regions is significantly regulated by five teleconnection patterns. Specifically, East Pacific-North Pacific (EP/NP) and East Atlantic/West Russia (EA/WR) patterns affect the burned area in North America, North Atlantic Oscillation (NAO) and East Atlantic (EA) patterns for Asia, and the Pacific-North American (PNA) pattern for Europe. Related to the teleconnections, the larger burned area is attributable to warmer surface by an anomalous high-pressure above and drier surface due to less moisture transport from the neighboring oceans. The results improve our understanding of driving forces of interannual variability of boreal fires and then regional and global carbon budgets.

How to cite: Zhao, Z., Lin, Z., and Li, F.: Influence of Atmospheric Teleconnections on Interannual Variability of Boreal Fires, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8323, https://doi.org/10.5194/egusphere-egu2020-8323, 2020.

Meteorology has a strong impact on forest fires. Meteorological parameters such as temperature, relative humidity, wind speed and precipitation alter the fuel loading in forests, control the changes in spatial distribution, intensity and frequency of forest fires and changes in forest fire season. Hence, it is important to understand the relationship between forest fires and meteorological factors and build models that can simulate these relationships.

The Canadian Forest Fire Danger Rating System (CFFDRS) has been used globally to assess and predict the fire behavior in various forest ecosystems. The Fire Weather Index (FWI) of CFFDRS models the relationship between meteorology and forest fires. In this study we calibrate the FWI over Indian forests using percentile analysis and logistic regression technique and test the performance using satellite-derived (MODIS daily fire data from 2003-2018) fire count and Fire Radiative Power (FRP). As the Indian forest landscape is highly heterogeneous, we calibrate the FWI over 4 FWI zones namely Himalayan, Deciduous, Western Ghats and Thorn forests based on IGBP forest classification and Koppen climatic zones.  Five fire danger classes having thresholds of 99^th, 95^th, 90^th, 80^th and 70^thof FWI percentiles have been defined with decreasing severity. Results show that the calibrated FWI is capable of simulating the forest fire behavior over India. Sensitivity studies show that temperature and relative humidity are the key controlling factors of forest fires over India.

This study is one of the first attempts to use fire models to simulate fire behavior over India. It can serve as a launchpad for further work on fire hazard prediction and effects of climate change on fire hazard in India.

How to cite: Barik, A. and Baidya Roy, S.: Effects of meteorology on forest fires in India: A modeling study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18317, https://doi.org/10.5194/egusphere-egu2020-18317, 2020.

Forest fire is a natural disaster threatening global human well-beings as well as a crucial disturbance agent driving forest landscape changes. The remotely sensed burned area (BA) products can provide spatially and temporally continuous monitoring of global fires, but the accuracies remain to be improved. We firstly developed a hybrid burned area mapping approach, which integrated the advantages of a 250 m global BA product (CCI_Fire) and a 30 m global forest change (GFC) product, to generate an improved 250 m BA product (so-called CCI_GFC product). Based on 248 fire patches derived from Landsat imagery, the results showed that the CCI_GFC product improved the CCI_Fire product substantially, which are significantly better than MCD64A1 product. According to the CCI_GFC, we found the total BA in the past 17 years was about 12.1 million ha in China, which approximately covered 6.1% of the total forested areas with a significantly decreased trend through Mann-Kendall test (Tau= -0.47, P<0.05) . We conducted a grid analysis (0.05°×0.05°) to determine the hot spots of forest fire from 2001 to 2017. We also quantified fire characteristics on frequency, spatial distribution, and seasonality in terms of Burned Forest Rate (BFR), hot spot areas, and fire seasons, respectively. We found that low frequency burns with a 0<BFR≤20% in 17 years covered 64% of total grids; the medium-low frequency burns (20%<BFR≤40%), the medium frequency burns (40%<BFR≤60%), the medium-high frequency burns (60%< BFR≤80%) accounted for 15%, 7%, 4% respectively; the high frequency burns (80%<BFR≤100%) and extremely high burns (100%<BFR≤120%) together occupy 10% of total grids which mainly distributed in Xiao Hinggan mountains, south China, and southwest China. The seasonality of forest fires differed substantially among eco-regions. The fire seasons of two temperate forest eco-regions are spring and autumn. The two peak fire months are May and October, in which about 22% and 37% of the total burned area were founded respectively. As a comparison, fire seasons in tropical and subtropical eco-regions are spring and winter (i.e., November to March of the next year), which accounted 88% of the total burned area. Our study clearly illustrated the characteristics of forest fire patterns in the past 17 years, which highlighted the remarkable achievements due to a nationwide implementation of fire prevention policy. At the same time, we emphasized that it is critically important to regard the long-term forest fire dynamics to design scientific and reasonable strategies or methods for fire management and controlling, which will be of sound significance to optimize the allocation of financial resources on fire management, and to achieve sustainable management of forests.

How to cite: Fang, L., Qiao, Z., and Yang, J.: The spatio-temporal characteristics of forest fires in China: observations from hybrid remote sensing data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2281, https://doi.org/10.5194/egusphere-egu2020-2281, 2020.

Fire is a natural disturbance in the Brazilian savannas, Cerrado, with substantial ecological and economic impacts. Most studies have characterized the fire regime in this biome using climate drivers but neglected the geographical variation of anthropogenic activities. These factors can trigger inappropriate fire-fighting decisions and biodiversity conservation policies. This takes special relevance in fire-prone biomes with recent fire management policies as Cerrado, which have been highly modified over the last decades due to changes in land use and climate. 

Here, we aim to identify how variations in climate and anthropogenic drivers influence burned area (BA) trends at the regional level (microregions) in Cerrado. We evaluated satellite-derived BA (MCD64, collection 6) for 172 microregions from 2001 to 2018 across the entire biome. The Canadian Forest Fire Weather Index (FWI) was used as a proxy of climate using meteorological variables from ECMWF’s ERA5 reanalysis product. The human leverage, considered here as population density (PD) and land use (LU), were derived, respectively, from the annual census of the Brazillian Institute of Geography and Statistics (IBGE) and from a Brazilian platform of annual land use/cover mapping (MapBiomas). Recent BA trends considering the drivers FWI, LU and PD, were estimated using the non-parametric Theil-Sen regression and the modified Mann-Kendall test. 

Results showed BA trends over the last 18 years were significant and spatially contrasted along Cerrado: positive trends were found in the north-eastern region (in particular, the most recent agricultural frontier in Brazil: MATOPIBA) whereas the south-western region showed negative trends. PD showed positive trends in all microregions and, similarly, LU obtained positive trends over most of Cerrado. Positive FWI trends were also found over the central and north-eastern regions and FWI was the driver that explained most of BA variance in Cerrado. LU and PD were found to have much more complex relations with BA. Moreover, regarding the seasonal variability of microregions with positive and negative trends, the former were found to begin earlier in June and last longer, indicating that the overall fire season in Cerrado may be extending. 

The approach presented here allows the exploration of recent trends affecting fires, crucial to inform and support better allocation of resources in fire management under current and future conditions.

The study was funded by Conselho Nacional de Desenvolvimento Científico e Tecnológico, Brazil (CNPQ) through grants 305159/2018-6 and 441971/2018-0. P. Silva is funded by Fundação para a Ciência e a Tecnologia (FCT), grant number SFRH/BD/146646/2019.

How to cite: Silva, P. S., Rodrigues, J. A., Santos, F. L. M., Nogueira, J., Pereira, A. A., Peres, L. F., Oom, D., DaCamara, C. C., Pereira, J. M. C., and Libonati, R.: Burned area trends in the Brazilian Cerrado: the roles of climate and anthropogenic drivers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20907, https://doi.org/10.5194/egusphere-egu2020-20907, 2020.

Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) was the most comprehensive investigation on the impact of wildfire and biomass smoke on air quality and weather in the continental United States, and took place in the late summer of 2019. FIREX-AQ explored the chemistry and fate of trace gases and aerosols in smoke with four instrumented research aircraft, satellites, ground-based fixed and mobile laboratories, modeling/forecasting, and coordinated airborne and ground-based fuels information gathering. It focused on both northwestern wildfires and the southeastern U.S. agricultural/prescribed burning.

FIREX-AQ was primarily funded by the US public, hence, the quality-assured dataset acquired from all aspects of the mission has become available to the public, including to the international community. FIREX-AQ data is available for use by researchers around the globe to advance understanding of all the impacts of fire on the atmosphere and on humanity.

Both in-situ and remote sensing data sets were acquired with the NASA DC-8 flying laboratory, while the NASA ER-2 supported several satellite emulators, the NOAA Chem-Otter Twin Otter focused on in situ measurements close to fires and in the dark, and the NOAA Met-Otter Twin Otter supported fire radiative power measurements and wind-profiler measurements to assess fire feedbacks on dynamics. NASA and Aerodyne, Inc. mobile labs focused measurements at very young plume age and in areas (for example valley drainage flow) relevant to air quality, and multiple temporary NASA AERONET sun photometer/lidar observations sites and mobile measurement platforms (“DRAGON”) were deployed to assess vertically resolved influences of smoke on light.

Extensive modeling efforts and meteorological forecasting efforts associated with the measurements resulted in reports that are also public. Coordination with the US Department of Agriculture and various academic institutions enabled inclusion of detailed fuels information including fuel type  and density as well as post-fire information in some cases. Coordination on prescribed burns of different fuels and in different regions in the US provide case studies for connecting emissions to fuels.

A detailed overview of the entire effort is available on-line at: https://www.esrl.noaa.gov/csd/projects/firex-aq/

How to cite: Schwarz, J. and the FIREX-AQ Science Team: The FIREX-AQ 2019 Dataset Is Public, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20755, https://doi.org/10.5194/egusphere-egu2020-20755, 2020.

A simple variance-maximization approach, based on 19 years of weekly Moderate Resolution Imaging spectroradiometer (MOPITT) CO vertical measurements, was employed to quantify the spatial distribution of the global seasonal biomass burning region. Results demonstrate there are a few large-scale and typical biomass burning regions responsible for most of the biomass burning emissions throughout the world, with the largest of these such regions located in Amazonian South America, Western Africa, Indonesia, and Northern Southeast Asia (Eastern India, Northern Myanmar, Laos, Vietnam and Eastern Bangladesh), which are highly associated with the results of Global Fire Emission Database(GFED). The CO is primarily lofted to and spreads downwind at 800mb or 700mb with three exceptions: The Maritime Continent and South America where there is significant spread at 300mb consistent with known deep- and pyro-convection; and Southern Africa where there is significant spread at 600mb. The total mass of CO lofted into the free troposphere ranges from 46% over Central Africa to 92% over Australia.

How to cite: Lin, C. and Cohen, J.: New simple approach to understand the spatial and vertical distribution of biomass burning CO emission based on the MOPITT vertical measurements, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9220, https://doi.org/10.5194/egusphere-egu2020-9220, 2020.

Fire emissions are a critical component of carbon and nutrient cycles and strongly affect climate and air quality. Dynamic global vegetation models (DGVMs) with interactive fire modeling provide important estimates for long-term and large-scale changes in fire emissions. Here we present the first multi-model estimates of global gridded historical fire emissions for 1700-2012, including carbon and 33 species of trace gases and aerosols. The dataset is based on simulations of nine DGVMs with different state-of-the-art global fire models that participated in the Fire Modeling Intercomparison Project (FireMIP), using the same and standardized protocols and forcing data, and the most up-to-date fire emission factor table based on field and laboratory studies in various land cover types. We evaluate the simulations of present-day fire emissions by comparing them with satellite-based products. The evaluation results show that most DGVMs simulate present-day global fire emission totals within the range of satellite-based products. They can capture the high emissions over the tropical savannas and low emissions over the arid and sparsely vegetated regions, and the main features of seasonality. However, most models fail to simulate the interannual variability, partly due to a lack of modeling peat fires and tropical deforestation fires. Before the 1850s, all models show only a weak trend in global fire emissions, which is consistent with the multi-source merged historical reconstructions used as input data for CMIP6. On the other hand, the trends are quite different among DGVMs for the 20th century, with some models showing an increase and others a decrease in fire emissions, mainly as a result of the discrepancy in their simulated responses to human population density change and land use and land cover change (LULCC). Our study provides an important dataset for further development of regional and global multi-source merged historical reconstructions, analyses of the historical changes in fire emissions and their uncertainties, and quantification of the role of fire emissions in the Earth system. It also highlights the importance of accurately modeling the responses of fire emissions to LULCC and population density change in reducing uncertainties in historical reconstructions of fire emissions and providing more reliable future projections.

How to cite: Li, F. and the FireMIP: Historical (1700-2012) global multi-model estimates of the fire emissions from the Fire Modeling Intercomparison Project (FireMIP), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6185, https://doi.org/10.5194/egusphere-egu2020-6185, 2020.

Wildfires are a major environmental problem that the current society must face and climate change will increase the number and intensity of wildfires during the next years. One of the problems is the toxicity of the pollutants emitted from biomass burning, including particulate matter (PM), carbon monoxide, methane, nitrogen oxides, volatile organic carbon, and some secondary pollutants. Some of these chemicals have demonstrated to impact human health, being responsible for increases on cardiovascular and respiratory morbidity and mortality (Johnston et al., 2012). These facts contribute to the deterioration of the air quality, therefore causing afflictions that may even end up in death. Wildfires are a worldwide concern, but in Europe the southern countries are the most affected. Thus, the estimation of the effects of wildfires on human health due to PM exposure is fundamental to manage health resources and public funds. Portugal was one of the European countries most affected by wildfires in the last decade, yet there is a lack of knowledge regarding impacts of the wildfire-related pollutants on the population mortality.

This study aims to describe the pattern of wildfires occurring in a period of 16 years (2001-2016) during the fire season (June, July, August and September) and to assess the impact of wildfire-generated PM₁₀ on the Portuguese population mortality, considering the fires that produced a burned area equal or above 1000 ha.

Data for PM₁₀ measured in background air quality monitoring stations was obtained from the Portuguese Environment Agency. All-cause (excluding injuries, poisoning and external causes) and cause-specific mortality (circulatory and respiratory) data was provided by Statistics Portugal. PM₁₀ concentrations were correlated with the burned area. Associations between PM₁₀ exposure and all-cause and cause-specific mortalities were studied using Poisson regression models. We found significant correlation between burned area and mortality in some NUTS, in particular, inland and north of Portugal mainland. Also, a good and significant correlation between burned area and PM₁₀ is found. This means that big fires have an impact on the dwellers health due to Particulate Matter causing diseases and even provoking the death.

Acknowledgements

This work was financially supported by project UID/EQU/00511/2019 - Laboratory for Process Engineering, Environment, Biotechnology and Energy – LEPABE funded by national funds through FCT/MCTES (PIDDAC). S. Augusto was supported by FCT-MCTES (SFRH/BPD/109382/2015). L. Palacios-Peña thanks to the scholarship FPU14/05505 of the Education, Culture and Sport Ministry. We acknowledge the project ACEX (CGL-2017-87921-R) of the Spanish Ministry of Economy and Competitiveness, the Fundación Biodiversidad of the Spanish Ministry for the Ecological Transition, and the FEDER European program, for support to conduct this research.

How to cite: Jiménez-Guerrero, P., Augusto, S., Palacios-Peña, L., Ratola, N., and Tarín-Carrasco, P.: Assessment of the impacts of PM10 due to wildfires on human mortality in Portugal, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6045, https://doi.org/10.5194/egusphere-egu2020-6045, 2020.

Science Question:  How can we use two new geostationary satellite-based algorithms to constrain wildfire plume modeling simulations?

Method:  Our approach is twofold. Combining NASA’s legacy MODIS products with the GOES Advanced Baseline Imager imagery, the state-of-the-art 3D-Wind algorithm, we first compare satellite-based detected wildfire plume injection heights with CMAQ, a chemical transport model. The validated GOES-MODIS 3D-Wind algorithm provides plume dynamics data with < 200 m vertical resolution for plume height and < 0.5 m/s for plume speed. Secondly, we compare aerosol type observations from the novel Multi-Angle Geostationary Aerosol Research Algorithm (MAGARA) to constrain modeled smoke hotspots and dispersion patterns of aerosols. Consistently modeled meteorology and extensive satellite coverage combine to produce more accurate plume injection heights and dispersion patterns, especially in areas where ground measurements are limited or absent. We compare the results of the two novel algorithms, 3D-Wind and MAGARA, to the 2018 Camp Fire event CMAQ runs. 

Impact:  Geostationary satellite wildfire plume-attribute products provide spatiotemporal context and can decrease errors in plume characterization. 

Why It Matters:  According to the EPA, wildland fires contributed approximately 30 percent of directly emitted fine particulate matter, linked to premature death from heart and lung disease. By capturing the dynamic wildfire plume dispersion, height, and winds, we can determine if fire plumes stay within or shoot above the planetary boundary layer and constrain modeling results. Improved accuracy, coverage, and characterization of plume injection height data increase the effectiveness of management methods that reduce and estimate smoke exposure.

How to cite: Friberg, M., Zou, Y., Limbacher, J., Wu, D., Carr, J., and O’Neill, S.: Comparing Wildfire GOES-based Stereo-Plume Heights, Winds, and Aerosol Property from 3D-Wind and MAGARA Algorithms to CMAQ simulations: A 2018 Camp Fire Study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11097, https://doi.org/10.5194/egusphere-egu2020-11097, 2020.

Emissions of trace gases and particles from fires have a major impact on climate, visibility, air quality, and public health. Biomass burning emissions include reactive nitrogen gases, in particular, ammonia (NH₃). NH₃ is a short-lived gas that acts as precursor for secondary aerosols formed in the downwind plume. This process is still poorly constrained.

In summer 2019, NASA and NOAA carried out the joint airborne FIREX-AQ (Fire Influence on Regional to global Environments and Air Quality) mission over the continental US to sample plumes from wildfires and agricultural fires. On board the NASA DC-8, we used a modified PTR-ToF-MS instrument for measuring NH₃ in situ and at high time resolution. Over the course of the mission, we collected a large set of NH₃ data in plumes associated with different fire types and burning conditions. Herein, we will present exemplary data and show results of our initial analyses.

How to cite: Tomsche, L., Mikoviny, T., Nowak, J. B., Piel, F., and Wisthaler, A.: In situ ammonia measurements in wildfire and agricultural fire plumes in the US, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12112, https://doi.org/10.5194/egusphere-egu2020-12112, 2020.

Biomass burning (BB) is known to contribute significantly to the global budgets of atmospheric trace gases and aerosols.  Approximately 1.6–4.1 Pg of CO₂, 11–53 Tg CH₄ and 0.1–0.3 Tg of N₂O is emitted to the atmosphere per year as a result of biomass burning on a global scale (Crutzen and Andreae, 2016). The contribution of BB to global GHG budgets is likely to increase over time due to climate feedback of warming and more widespread drought conditions increasing the likelihood and spread of wildfire events (Liu et al., 2014).

It is estimated that Africa accounts for approximately 52% of all BB carbon emissions, with the Northern Sub-Saharan African region alone accounting for 20-25% of global BB carbon emissions (van der Werf et al. 2010; Ichoku et al. 2016). Many of these fires are anthropogenic in origin, and occur for reasons such as clearing land for agricultural use, management of natural savannah vegetation, or as pest control (Andreae, 1991).  Despite the African contribution to global BB emissions, there are limited in situ studies of African wildfire emissions.

In situ measurements of CH₄, CO₂ and N₂O and CO in biomass burning plumes were carried out in Senegal in February 2017 and in Uganda in January 2019 during the Methane Observations and Yearly Assessments (MOYA) project. These observations were carried out using the Facility for Airborne Atmospheric Measurements BAe-146 Atmospheric Research Aircraft (ARA), which is fitted with a range of specialist instrumentation for in situ trace gas sampling. Emission factors for these species were calculated for both near-field and far-field biomass burning plumes. A notable difference in the linear trend between methane emission factors and completeness-of-combustion was identified between Senegalese and Ugandan fires.

How to cite: Barker, P., Allen, G., Bannan, T., Pitt, J., Bauguitte, S., Nisbet, E., and Lee, J.: Airborne measurements of trace gas emissions from African biomass burning during the MOYA Campaign, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15886, https://doi.org/10.5194/egusphere-egu2020-15886, 2020.

Carbon Monoxide (CO) is an important atmospheric trace gas, and among the key O₃ precursors in the troposphere, alongside NO_x and VOCs. It is among the most important sinks of OH radical in the atmosphere, which controls lifetime of CH₄ — a major greenhouse gas. Biomass burning sources contribute about 25% to the global emissions of CO, with the remaining CO being either emitted from anthropogenic sources, or being chemically formed in the atmosphere. Because of CO tropospheric lifetime is about two months; it can be transported in the atmosphere thus its sources have a hemispheric impact on atmospheric composition.

The extent of the impact of biomass burning to remote areas of the world through long range transport is here investigated using the global 3-dimensional chemistry transport model TM4-ECPL. For this, tagged biomass burning CO tracers from the 13 different HTAP (land) source regions are used in the model in order to evaluate the contribution of each source region to the CO concentrations in the 170 HTAP receptor regions that originate from biomass burning. The global simulations cover the period 1994—2015 in order to derive climatological transport patterns for CO and assess the contribution of each of the source regions to each of the receptor regions in the global troposphere. The CO simulations are evaluated by comparison with satellite observations from MOPITT and ground based observations from WDCGG. We show the significant impact of biomass burning emissions to the most remote regions of the world.

How to cite: Daskalakis, N., Kanakidou, M., Vrekoussis, M., and Gallardo, L.: Climatological Biomass Burning CO – Where it comes from and where it goes., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17829, https://doi.org/10.5194/egusphere-egu2020-17829, 2020.

Fires constitutes a key process in the Earth system (ES), being driven by climate as well as affecting the climate by changing atmospheric composition and its impact on the terrestrial carbon cycle. However, global modelling studies on the effects of fires on atmospheric composition, radiative forcing and climate have been very limited to date. The aim of this work is the development and application of a fully coupled vegetation-fire-chemistry-climate ES model in order to quantify the impacts of fire variability on atmospheric composition-climate interactions in the present day. For this, the INFERNO fire model is coupled to the atmosphere-only configuration of the UK’s Earth System Model (UKESM). This fire-atmosphere interaction through atmospheric chemistry and aerosols allows for fire emissions to feedback on radiation and clouds changing weather which can consequently feedback on the atmospheric drivers of fire. Additionally, INFERNO was updated based on recent developments in the literature to improve the representation of human/economic factors in the anthropogenic ignition and suppression of fire. This work presents an assessment of the effects of interactive fire coupling on atmospheric composition and climate compared to the standard UKESM1 configuration which has prescribed fire emissions. Results show a satisfactory performance when using the fire-atmosphere coupling (the “online” version of the model) when compared to the offline UKESM that uses prescribed fire. The model can reproduce observed present day global fire emissions of carbon monoxide (CO) and aerosols, despite underestimating the global average burnt area. However, at a regional scale there is an overestimation of fire emissions over Africa due to the miss-representation of the underlying vegetation types and an underestimation over Equatorial Asia due to a lack of representation of peat fires.

How to cite: Teixeira, J., O'Connor, F., Unger, N., and Voulgarakis, A.: Coupling interactive fire with atmospheric composition and climate in the UK Earth System Model (UKESM), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19800, https://doi.org/10.5194/egusphere-egu2020-19800, 2020.

Mainland and maritime Southeast Asia is home to more than 655 million people, representing nearly 10% of the global population. The dry season in this region is typically associated with intense biomass burning activity, which leads to a significant increase in surface air pollutants that are harmful to human health, including ozone (O₃) and fine (radii smaller than 2.5 microns) particulate matter (PM_2.5). Latitude-based differences in dry season timing and land use distinguish two regional biomass burning regimes: (1) agricultural waste burning on the peninsular mainland from February through April and (2) coastal peat burning across the equatorial islands in September and October. The type and amount of material burned determines the chemical composition of emissions and subsequently their impact on regional air quality. Understanding the individual and collective roles of these biomass burning regimes is a crucial step towards developing effective air quality mitigation strategies for Southeast Asia. Here, we use the nested GEOS-Chem atmospheric chemistry transport model (horizontal resolution of 0.25° x 0.3125°) to simulate fire-atmosphere interactions over Southeast Asia during March and September of 2014, when emissions peak from the two regional burning seasons. Based on our analysis of model output, we report how these two distinct biomass burning regimes impact the photochemical environment over Southeast Asia and what the resulting consequences are for surface air quality. We will also present a critical evaluation of our model using ground-based and satellite observations of atmospheric composition across the region.

How to cite: Marvin, M., Palmer, P., Yao, F., Latter, B., Siddans, R., and Kerridge, B.: Characterizing two distinct biomass burning regimes over Southeast Asia and their impacts on regional air quality, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7653, https://doi.org/10.5194/egusphere-egu2020-7653, 2020.

The boreal forest is one of the largest terrestrial carbon reservoirs on Earth and accounts for approximately 30% of the world’s forest cover. The boreal carbon balance is thus of global significance. Wildfires affect the boreal carbon balance, releasing large amounts of carbon into the atmosphere when soil organic layers and aboveground biomass are combusted. The boreal forest is warming faster than the global average. These higher temperatures lead to increases in the frequency and severity of wildfire disturbance in boreal regions.

Significant progress has been made in quantifying carbon combustion in North American boreal forests, yet few measurements have been conducted in the larch dominated boreal forests of Northeast Siberia. Deciduous needleleaf larch forest growing on continuous permafrost is a unique ecosystem of Siberia. Although these larch forests cover approximately 20% of the boreal biome, the consequences of intensifying fire regimes on the carbon stocks and vegetation dynamics of these ecosystems remain poorly understood.

We conducted a field campaign in larch forests around Yakutsk, Northeast Siberia, during the summer of 2019 with the goal of filling parts of these knowledge and data gaps by collecting ground measurements of carbon combustion from two large fire events in 2017 and 2018. During this campaign, we sampled 42 burned sites in two fire scars that cover gradients of fire severity, vegetation composition and landscape position. Within these sites, we performed a wide range of measurements to quantify aboveground and belowground carbon emissions, constrained by data from 12 unburned sites. We also assessed post-fire recovery and active layer deepening. We investigated major drivers of pre-fire carbon stocks and subsequent combustion at the site level. Our results will reduce uncertainties in larger scale estimates of carbon emissions from Siberian fires which is in turn essential for assessing the implications of the climate-induced intensification of fire regimes for the global carbon cycle.

How to cite: Delcourt, C. J., Izbicki, B., Kukavskaya, E. A., Mack, M. C., Maximov, T. C., Petrov, R. E., Rogers, B. M., Scholten, R., Shestakova, T., van der Werf, G., van Wees, D., and Veraverbeke, S.: Carbon emissions from wildfires in larch forest ecosystems of Northeast Siberia, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1939, https://doi.org/10.5194/egusphere-egu2020-1939, 2020.

The Moderate Resolution Imaging Spectroradiometer (MODIS) has been widely used for wildfire occurrence and distribution detecting and fire risk assessments. Compared with its commission error, the omission error of MODIS wildfire detection has been revealed as a much more challenging, unsolved issue, and ground-level environmental factors influencing the detection capacity are also variable. This study compared the multiple MODIS fire products and the records of ground wildfire investigations during December 2002–November 2015 in Yunnan Province, Southwest China, in an attempt to reveal the difference in the spatiotemporal patterns of regional wildfire detected by the two approaches, to estimate the omission error of MODIS fire products based on confirmed ground wildfire records, and to explore how instantaneous and local environmental factors influenced the wildfire detection probability of MODIS. The results indicated that across the province, the total number of wildfire events recorded by MODIS was at least twice as many as that in the ground records, while the wildfire distribution patterns revealed by the two approaches were inconsistent. For the 5145 confirmed ground records, however, only 11.10% of them could be detected using multiple MODIS fire products (i.e., MOD14A1, MYD14A1, and MCD64A1). Opposing trends during the studied period were found between the yearly occurrence of ground-based wildfire records and the corresponding proportion detected by MODIS. Moreover, the wildfire detection proportion by MODIS was 11.36% in forest, 9.58% in shrubs, and 5.56% in grassland, respectively. Random forest modeling suggested that fire size was a primary limiting factor for MODIS fire detecting capacity, where a small fire size could likely result in MODIS omission errors at a threshold of 1 ha, while MODIS had a 50% probability of detecting a wildfire whose size was at least 18 ha. Aside from fire size, the wildfire detection probability of MODIS was also markedly influenced by weather factors, especially the daily relative humidity and the daily wind speed, and the altitude of wildfire occurrence. Considering the environmental factors’ contribution to the omission error in MODIS wildfire detection, we emphasized the importance of attention to the local conditions as well as ground inspection in practical wildfire monitoring and management and global wildfire simulations.

How to cite: Ying, L., Shen, Z., Yang, M., and Piao, S.: Wildfire Detection Probability of MODIS Fire Products under the Constraint of Environmental Factors: A Study Based on Confirmed Ground Wildfire Records, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8347, https://doi.org/10.5194/egusphere-egu2020-8347, 2020.

Spatial patterns and temporal changes in live fuel moisture content (LFMC) have been intensively estimated from satellite observations in the optical domain of the electromagnetic spectrum. Such estimates are valuable to predict regional to local variations in fire danger (Yebra et al., 2018). However, optical satellite measurements saturate fast in dense canopies and are generally hampered during cloud cover. Microwave satellite observations can penetrate clouds and the canopy (dependent on the wavelength) and hence have been intensively used to derive surface soil moisture (SSM) or vegetation optical depth (VOD), which is a proxy for vegetation water content (Moesinger et al., 2019). However, the relationship of microwave VOD to LFMC and the predictive capabilities of VOD for fire dynamics have not yet been investigated at large scales. Here we aim to assess how VOD reflects changes in LFMC and the sensitivity of VOD to different properties of fire dynamics such as fire occurrence, size, burned area, and fire radiative power.

We compared VOD in different microwave bands (Ku-, X-, and C-band) from the VODCA dataset (Moesinger et al., 2019) with LFMC from MODIS retrievals (Yebra et al., 2018). Our results demonstrate that VOD and LFMC are moderately to highly correlated but the strength and shape of the relationship depends on land cover type. In a preliminary analysis, we then predicted the probability of fire occurrence (Andela et al., 2019) and fire radiative power (Kaiser et al., 2012) from VOD, SSM, and climate data using the random forest machine learning approach. The initial results show that VOD is a skilful predictor for continental-scale fire dynamics. Furthermore, our results suggest that the combination of LFMC from optical satellites with microwave SSM and VOD might allow to comprehensively estimate ecosystem fuel moisture conditions. Hence microwave satellite observations will be valuable for the development of integrated fire danger prediction systems.

References

Andela, N., Morton, D.C., Giglio, L., Paugam, R., Chen, Y., Hantson, S., Werf, G.R. van der, Randerson, J.T., 2019. The Global Fire Atlas of individual fire size, duration, speed and direction. Earth Syst. Sci. Data 11, 529–552. https://doi.org/10.5194/essd-11-529-2019

Kaiser, J.W., Heil, A., Andreae, M.O., Benedetti, A., Chubarova, N., Jones, L., Morcrette, J.-J., Razinger, M., Schultz, M.G., Suttie, M., van der Werf, G.R., 2012. Biomass burning emissions estimated with a global fire assimilation system based on observed fire radiative power. Biogeosciences 9, 527–554. https://doi.org/10.5194/bg-9-527-2012

Moesinger, L., Dorigo, W., Jeu, R. de, Schalie, R. van der, Scanlon, T., Teubner, I., Forkel, M., 2019. The Global Long-term Microwave Vegetation Optical Depth Climate Archive VODCA. Earth Syst. Sci. Data Discuss. 1–26. https://doi.org/10.5194/essd-2019-42

Yebra, M., Quan, X., Riaño, D., Rozas Larraondo, P., van Dijk, A.I.J.M., Cary, G.J., 2018. A fuel moisture content and flammability monitoring methodology for continental Australia based on optical remote sensing. Remote Sens. Environ. 212, 260–272. https://doi.org/10.1016/j.rse.2018.04.053

How to cite: Forkel, M., Andela, N., Dorigo, W. A., Drüke, M., Harrison, S. P., Moesinger, L., Schmidt, L., and Yebra, M.: Characterising vegetation fuel moisture conditions from microwave satellite observations for fire danger prediction at continental to global scales, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10860, https://doi.org/10.5194/egusphere-egu2020-10860, 2020.

Wildfires are essential for ecosystem development, thereby affecting the global carbon cycle. Soil moisture is a major driver of wildfires, however, due to a lack of large-scale observations it remains unclear which spatio-temporal soil moisture patterns promote wildfires. Using satellite-based soil moisture data, we show contrasting soil moisture anomalies preceding the locally largest wildfires in space and time. In arid regions wetter-than-average soils enable sufficient biomass growth required to fuel fires. By contrast, in humid regions fires are typically preceded by dry soil moisture anomalies inducing suitable ignition conditions and flammability in an otherwise too wet environment. In both regions, soil moisture anomalies are continuously decreasing over the months before the fire occurrence, often from above-normal to below-normal. These signals are most pronounced for larger fires in sparsely populated areas with low human influence. Resolving natural soil moisture-fire interactions supports fire modelling and enables improved fire forecasts and early warning.

How to cite: Oh, S., Hou, X., and Orth, R.: Wildfires promoted by contrasting soil moisture anomalies in humid versus arid regions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5347, https://doi.org/10.5194/egusphere-egu2020-5347, 2020.

Forest fires are recurrent in Portugal, either due to climate conditions, to land use change, or to a combination of both. Wet and mild winters, together with dry and warm summers, favour the growth of vegetation and its subsequent low moisture content, increasing fuel availability. The assessment and management of fuel loads is essential to understand and minimize fire risk. The structural risk depends on the type of available fuel and on the age of vegetation. Therefore, reducing fuel loads is often required to mitigate fire severity.  

Active fire observations of fire radiative power (FRP) have been shown to be correlated to rates of biomass combustion. The Meteosat FRP-PIXEL product is delivered in near real-time by the EUMETSAT Land Surface Analysis Satellite Applications Facility (LSA SAF), since 2004 with 15-min temporal resolution. We propose to do the first assessment, for Portugal, of the relationship between Fire Radiative Energy (FRE) per fire and pre-fire fuel load estimates, as obtained from Dry Matter Productivity (DMP), disseminated by Copernicus Global Land Service (CGLS) at 1km spatial resolution since 1999. The analysis is performed for the main land cover types in Portugal that show high sensitivity to wildfires. The severest wildfire events in Portugal since 2004 are also analysed with detail, namely the fires of 2005, 2012 and 2017 and the obtained results related with soil moisture, fuel type and fire size.

Acknowledgements: This study was performed within the framework of the LSA-SAF, co-funded by EUMETSAT This work was partially supported by national funds through FCT (Fundação para a Ciência e a Tecnologia, Portugal) under projects FIRECAST (PCIF/GRF/0204/2017) and IMPECAF (PTDC/CTA-CLI/28902/2017).

How to cite: Alonso, C., Gouveia, C. M., and Páscoa, P.: Assessment of the relationship between pre-fire fuel estimates and Fire Radiative Power in Portugal, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19634, https://doi.org/10.5194/egusphere-egu2020-19634, 2020.

Wildfires in temperate regions like the UK can cause major impacts for ecosystems, society and human health and wellbeing. Under changing climate and land use patterns it is therefore important to better understand how we can assess the danger posed by fires in the landscape. Major wildfire events in the UK over recent years have highlighted the risk posed by wildfires, and has led to recognition of wildfire as an environmental hazard in the UK National Risk Register.

Fire Danger Rating Systems (FDRS) are designed to assess the fuel and weather to provide estimates of flammability and likely fire behaviour under those conditions. These danger ratings can inform management decisions for land managers, direct resourcing plans for FRS teams, and feed into strategic planning for local and national governments. However, the UK does not yet have a fit-for-purpose FDRS and we lack the fundamental scientific and end-user understanding to predict effectively the likelihood, behaviour and impact of wildfire incidents in the UK at present and under future climate and land use scenarios.

This poster will present the outline and structure of a new NERC-funded, multi-institution, 4-year project that will develop the underpinning knowledge and tools to develop a UK FDRS. We are very keen to hear from the wildfire community about ways in which this work could help you with your activities and to link up with other projects.

How to cite: Clay, G., Belcher, C., Doerr, S., Elliott, A., Hardiman, M., Kettridge, N., Millin-Chalabi, G., Morison, J., Santin, C., and Smith, T.: Toward a UK fire danger rating system: Understanding fuels, fire behaviour, and impacts, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19823, https://doi.org/10.5194/egusphere-egu2020-19823, 2020.

Weather has a major influence on wildfire behaviour, but heat and vapor fluxes produced by fuel consumption can also alter atmospheric conditions. Severe storms can develop from the intense convection that occurs in large wildfires. During Pedrógao Grande (Portugal) 17 June 2017 wildfire, atmospheric storm conditions played a decisive role in fire spread, with the fire becoming uncontrollable and ultimately causing 66 fatalities.

We present here preliminary simulations of the Pedrógrao Grande wildfire with the WRF-FIRE model, identifying the role that the fire could have played in the development of the storm and how the storm could have influenced the spread of the fire.​

How to cite: Senande Rivera, M. and Miguez-Macho, G.: Numerical simulation of pyro-convection caused by intense wildfire in Portugal, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19641, https://doi.org/10.5194/egusphere-egu2020-19641, 2020.

Fires are an important component in Earth system models (ESMs), they impact vegetation carbon storage, vegetation distribution, atmospheric composition and cloud formation. The representation of fires in ESMs contributing to CMIP phase 5 was still very simplified. Several Earth system models updated their representation of fires in the meantime. Using the latest simulations of CMIP6 we investigate how fire regimes change in the future for different scenarios and how land use, climate and atmospheric CO₂ concentration contribute to the fire regimes changes. We quantify changes in fire danger, burned area and carbon emissions on an annual and seasonal basis. Factorial model simulations allow to quantify the influence of land use, climate and atmospheric CO₂ on fire regimes.

We complement the information on fire regime change supplied by ESMs that include a fire module with a statistical modelling approach for burned area. This will use information from simulated changes in climate, vegetation and socioeconomic changes (population density and land use) provided for a set of different future scenarios. This allows the integration of information provided by global satellite products on burned area with the process-based simulations of climate and vegetation changes and information from socioeconomic scenarios.

How to cite: Lasslop, G., Hantson, S., Brovkin, V., Li, F., Lawrence, D., Rabin, S., and Shevliakova, E.: Future fires in the Coupled Model Intercomparison Project (CMIP) phase 6 , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22513, https://doi.org/10.5194/egusphere-egu2020-22513, 2020.