The increasing demand for renewable energy highlights the importance of accurate dust process forecasting in regions with abundant wind and solar resources, as it can create significant value for the sector. However, leading real-time operational global numerical weather prediction (NWP) models often lack dust modules due to computational resource limitations and application scenarios. Current 'Near-Real-Time' dust forecasting services can only run after the completion of NWP, failing to meet the timeliness requirements for reporting power generation plans to the power grids. This work proposes a global dust-weather integrated (iDust) model development paradigm, incorporating dust modules into the dynamical core. Utilizing approximately one-eighth of additional computing power extends the global 12 km resolution NWP with dust prediction capabilities. To evaluate the forecasting capabilities of iDust, a comparative study is conducted with the ECMWF CAMS forecast and NASA MERRA2 reanalysis, including verifications over China during March to May in 2023, as well as three extreme dust events. The results demonstrate that iDust has better intensities and timings than its counterparts in dust storm forecasting. Using iDust, the global 12-km 10-day hourly dust storm forecast simulation initiated at 00UTC can obtain results by 06UTC, enabling timely forecasting of severe dust storms with concentrations exceeding 1000 μg/m3 on a global scale. iDust's novel capability can fill the urgent forecasting needs of the renewable energy industry for extreme dust weather conditions, promoting the goal of the green energy transition.
How to cite: Chen, X., Chong, M., Lin, S.-J., Liang, Z., Ginoux, P., and Liang, Y.: iDust - The deep integration of dust and numerical weather prediction for renewable energy applications, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2318, https://doi.org/10.5194/egusphere-egu25-2318, 2025.
The impact of aerosol-meteorology feedback on the effectiveness of emission reduction for PM2.5: A modeling case study in Northern China
Meigen Zhang, Jing He, and Yi Gao
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
The quantification of the effectiveness of anthropogenic emission control measures is crucial for future air quality policies. Meteorology plays a vital role in haze pollution, and the interactions between aerosol and meteorology have been widely studied. However, it is not fully clear how aerosol-meteorology feedback affects the effectiveness of emission reduction for PM2.5, which limits our ability of optimizing anti-pollution policies. Here, with the two-way atmospheric chemical transport model WRF-Chem, the effects of aerosol-meteorology feedback on the effectiveness of emission reduction for PM2.5 during a winter severe haze event in 2016 over the Northern China Plain (NCP) are studied. In the more polluted area of NCP (MP_NCP) during the daytime, 20% emission reduction over NCP increases near-surface downward shortwave radiation by 4.62 W/m2, 2 m temperature by 0.08 ◦C, boundary layer height by 7.19 m and reduces 2 m relative humidity by 0.31% and thereby alleviates worsened meteorological conditions caused by aerosol effect. As a result, in MP_NCP, 20% emission reduction without aerosol-meteorology feedback leads to a decrease of 40.49 μg/m3 of near-surface PM2.5 and the above meteorological changes decrease near-surface PM2.5 concentration by 7.82 μg/m3, indicating that aerosol-meteorology feedback strengthens the effectiveness of emission reduction by 19%. In the less polluted area (LP_NCP), aerosol effect induced meteorological changes decrease PM2.5 concentration by 7.57 μg/m3 and 20% emission reduction without aerosol-meteorology feedback leads to a decrease of 13.15 μg/m3 in near-surface PM2.5. This reveals a remarkable enhancement of 58% in the effectiveness of emission reduction, which is much larger than that in MP_NCP. Such difference can be attributed to the presence of more clouds in LP_NCP, where the decrease in liquid water path, along with the increase in the planetary boundary layer height, jointly contributes to the PM2.5 decrease. Moreover, the effect of aerosol-meteorology feedback on the effectiveness of emission reduction for PM2.5 is nonlinear. With increasing PM2.5 concentration, the aerosol-meteorology feed back induced PM2.5 reduction first increases and then stabilizes once the PM2.5 concentration exceeds 350 μg/m3. This study can provide reference for air pollution control strategies.
Keywords: Emission reduction, Aerosol-meteorology feedback, WRF-Chem
How to cite: Zhang, M., He, J., and Gao, Y.: The impact of aerosol-meteorology feedback on the effectiveness of emission reduction for PM2.5: A modeling case study in Northern China, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2637, https://doi.org/10.5194/egusphere-egu25-2637, 2025.
The health impacts of air pollution and temperature variations are of increasing concern, particularly in urban environments where emissions and population densities are high. Short-term exposure to pollutants such as sulfur dioxide (SO₂), nitrogen dioxide (NO₂), suspended particulate matter (SPM), and oxidants (Ox) has been linked to adverse health outcomes, including increased rates of cardiovascular and respiratory diseases. Additionally, temperature fluctuations, especially during extreme weather conditions, exacerbate the vulnerability of populations to these pollutants, contributing to excess mortality.
Japan, with its diverse climate and urban landscape, presents a unique case for studying the interactions between air pollution, temperature, and mortality. Hiroshima, located in a temperate climate, and Sapporo, in a colder region, offer contrasting environments to examine the seasonal and regional variations in these associations. This study investigates the short-term associations between temperature, air pollutants (SO₂, NO₂, suspended particulate matter (SPM), and oxidants (Ox)), and mortality in Hiroshima and Sapporo, Japan, from January 1, 2012, to December 31, 2019. Using a time-stratified case-crossover study design, we examine the impacts on cardiovascular, respiratory, and general mortality, focusing on gender- and age-specific differences. Seasonal variations, comparing summer and winter periods, and different emission levels across the study period are also considered. By analyzing these interactions, this study aims to deepen the understanding of how short-term environmental factors and pollution levels influence health outcomes in urban populations, contributing to targeted public health interventions in Japan.
How to cite: Marggraf, C., Huang-Lachmann, J.-T., Hashizume, M., and Ng, C. F. S.: Short-Term Associations Between Temperature, Air Pollutants (SO₂, NO₂, SPM, Ox), and Mortality in Hiroshima and Sapporo, Japan (2012–2019): Age and Gender-Specific Differences Across Seasons, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19665, https://doi.org/10.5194/egusphere-egu25-19665, 2025.
Ozone (O3) concentration in the regional atmosphere of South China were shown to increase, but the recent variations in the context of dramatic emissions fluctuations remain unknow. In contrast to the overall increase determined elsewhere, O3 at a regional background site in South China decreased at a surprisingly high rate of -2.79 ppbv yr-1 during 2018-2023, which has not been seen before and was unlikely to be explained by the COVID-19 lockdowns. Significant reductions in O3 were only observed in summer and autumn. Three statistical methods were used to eliminate the impacts of meteorological variations on O3 trends, which were shown not to be the main cause of the O3 reduction. With the 2017 emission inventories (EIs), the Weather Research and Forecasting model coupled with Community Multiscale Air Quality (WRF-CMAQ) well reproduced the O3 in August 2018. Sensitivity tests indicated that meteorological variations explained at most half of the O3 reduction rate. Despite the significant drop in cargo throughput at Hong Kong (HK) terminals, ship emissions made a higher contribution to O3 in August 2023 than in the same period of 2018. The unexplained O3 decrease was likely due to reduced anthropogenic emissions in mainland China and HK. Simulations with a simple extrapolation based on the 2017 EIs did show that emission changes in the neighboring Pearl River Delta led to a decrease in O3. However, updated emissions are needed to clearly understand the effects of local and regional emission changes.
How to cite: Lyu, X.: What drove the rapid ozone reduction at a background site in South China during 2018-2023?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9564, https://doi.org/10.5194/egusphere-egu25-9564, 2025.
Extreme weather events, such as stagnation conditions and heatwaves, are known to exacerbate hazardous air quality situations by promoting the accumulation and persistence of pollutants like ozone (O3) in the near-surface environment. In particular, during the summer over the Iberian Peninsula (IP), extreme O3 values often exceed the 180 µg/m3 threshold, significantly impacting air quality and public health. While meteorological factors like high temperatures and radiation are important drivers of these events, classifying them based solely on synoptic weather patterns fails to capture the full scope of the risks involved. Even when events are classified under the same synoptic category, O3 concentration can vary greatly. This implies that variability is not only due to direct meteorological influences, but also other factors related to transport, previous concentrations or processes linked to surface conditions can modify emissions of compouds that affect O3 formation. In this regard, biogenic volatile organic compound (BVOC) emissions from vegetation can significantly influence O3 formation in a complex and non-linear way. The amount and type of vegetation, as well as the available soil moisture, modulate these emissions.
In this study, we conducted sensitivity experiments using the Weather Research and Forecasting model coupled with chemistry (WRF-Chem, version 4.6.0) to explore how factors like soil moisture and vegetation amount influence extreme O3 events over the IP. We first performed simulations varying leaf area index (LAI) and soil moisture (SM) by multiplying the original fields of SM (all layers) and LAI by a factor ranging from 0.25 to 2. The results indicate that decreasing the available soil water (-50%) increases BVOCs emission rates (20% spatial and temporal average), which is reflected in an increase in daily maximum O3 concentrations (10%). On the other hand, increasing the vegetation (50 %) leads to an increase in BVOC emission rates (10%), as well as in O3 concentrations (up to 10 %). The combined experiments exacerbated the changes, although most of the time they are smaller than the sum of the isolated experiments.
Regional Climate Models (RCMs) often use climatological variables to characterize vegetation. Some studies show that differences in vegetation fraction with respect to climatological values can reach up to 40% over the IP. We performed a series of simulations of extreme O3 occurrences, employing both observed and climatological values of vegetation. Preliminary results indicate that such differences in vegetation moderately modify final O3 concentrations, in most cases obtaining better agreement with observations.
Acknowledgements: Project PID2020-115693RB-I00 funded by MCIN/ AEI /10.13039/501100011033
How to cite: Segado-Moreno, L., Montávez, J. P., Garnés-Morales, G., Raluy-López, E., and Jiménez-Guerrero, P.: Understanding Drivers of Extreme Ozone Events: A Sensitivity Study with WRF-Chem, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20017, https://doi.org/10.5194/egusphere-egu25-20017, 2025.
Global emission patterns have changed significantly in the past decade as regions around the world started various reduction policies, notably marked by China's Air Pollution Prevention and Control Action Plan and IMO's regulations on shipping emissions. However, the climate response to these regional emission changes has not been fully quantified. Using two climate models (CESM2 and GISS), we conducted 80-year simulations and analyzed the last 70 years to study the radiative effects of emission changes during 2013-2023. Through designed 4 experiments using ABaCAS EI, CMIP6, and SEIM shipping emission inventories, we separated the climate impacts from three main sources: China, regions outside China, and global shipping emissions. We then used the FaIR model to evaluate their temperature responses.
Our model simulations show remarkable consistency in top-of-atmosphere radiative changes despite differences in aerosol-cloud interaction parameterizations. The total effective radiative forcing (ERF) is approximately 0.15 W/m², with China's emission changes contributing the largest forcing (0.06-0.07 W/m²), followed by other regions (0.04-0.05 W/m²) and shipping (0.04-0.05 W/m²). Spatial analysis reveals significant positive forcing (>2 W/m²) over East Asia (20°N-45°N, 100°E-125°E) with notable downstream effects. CESM2, with its higher resolution, shows stronger aerosol transport signals over the Pacific, while GISS exhibits weaker signals in regions far from sources.
While both models differ in simulating cloud-aerosol interactions, CESM2's more detailed aerosol and cloud microphysics schemes and stronger aerosol-cloud-radiation coupling capture more transport and indirect effects, though the result also has larger uncertainties. In the North Pacific region, both CESM2 and GISS simulate strong positive radiative forcing change, showing significant radiative anomalies consistent with CERES satellite observations of outgoing shortwave radiation changes during 2013-2023. Our results indicate that China's emissions, through downwind transport, contribute more to these radiative changes than shipping emissions.
The FaIR model results suggest that China's emission reductions have led to approximately 0.025°C warming, while global emission changes have contributed about 0.05°C. We also evaluated potential future temperature trends based on temperature response functions. These findings improve our understanding of how regional emission changes affect the global climate system and highlight the importance of coordinated emission reduction strategies across regions and sectors, considering the role of both continental and maritime emissions in global radiative forcing patterns and their implications for future climate policies.
How to cite: Wang, X., Zhao, B., Faluvegi, G., Zhang, Y., Yi, W., Shindell, D., and Wang, S.: Climate Response to a Decade of Anthropogenic Emission Changes (2013-2023), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17376, https://doi.org/10.5194/egusphere-egu25-17376, 2025.
Many studies have demonstrated the relationship between extreme meteorological events and air pollution with increased mortality. However, only a few studies attribute mortality excesses to compound events, where meteorological causes overlap with elevated atmospheric pollutant levels. In this work, we present a study on mortality excesses in Spain, air pollution, and their relationship with atmospheric circulation. Daily mortality rate data at a provincial level is used for the summer season for the period 2015-2022.
First, mortality extremes were categorized and related to preceding extreme atmospheric conditions. The results show that most mortality extremes are preceded by extreme atmospheric conditions, with a time lag that depends on the season and the variable considered. For instance, in Madrid during summer, the variables explaining mortality include temperature (minimum and maximum), ozone (O3), particulate matter (PM10), and their combinations. Influences from previous days are significant for more than 50% of cases, with a median lag of three days for ozone, two days for temperature, and one day for PM10, and deviations ranging from 1 to 3 days.
Once all days potentially associated with mortality extremes were identified, they were classified into different atmospheric circulation types (CTs) based on sea-level pressure (SLP), temperature at 850 mb, and geopotential height at 500 mb. This classification uses daily average fields derived from ERA5 reanalysis over a domain encompassing the entire Iberian Peninsula. For each identified CT, average fields of temperature, O3, and PM10 were calculated using CAMS reanalysis data. Additionally, the efficiency of each CT in all provinces was assessed. The results indicate that most situations leading to mortality extremes are associated with upper-level ridges, with the position and inclination of the ridge axis determining regional differences in the efficiency on mortality rates across the Iberian Peninsula.
Acknowledgments: The authors acknowledge Grant PID2020-115693RB-I00 funded by MCIN/AEI/ 10.13039/501100011033
How to cite: Garnés-Morales, G., Jiménez-Guerrero, P., Gil-Guirado, S., García-Fernández, E., Segado-Moreno, L., Raluy-López, E., and Montávez, J. P.: Meteorological Drivers of Compound Atmospheric Events Associated with High Mortality Rates in Spain, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18288, https://doi.org/10.5194/egusphere-egu25-18288, 2025.
New particle formation (NPF) is a process in which gaseous molecules in the atmosphere cluster together to form aerosol particles [1]. These particles contribute significantly to the total number of aerosols in the atmosphere, further influencing air quality and climate [2]. The environmental and climate effects of NPF largely depend on the particle growth (NPG) process; however, it remains poorly understood, especially in urban [3]. In this study, we performed simultaneous measurements of particle number size distributions (PNSD) and chemical compositions at the ground and at 260 m based on the 325 m meteorological tower in urban Beijing. By comparing the NPG process at the two heights, we provide new insights into the interactions between boundary layer dynamics and NPG in megacity [4, 5].
Our results show that although NPG occurred at both heights, significant differences of NPG between 260 m and the ground level were observed in megacity. When vertical diffusion is sufficient, gaseous precursors from the surface could be transported to higher altitudes. The lower temperature and higher relative humidity aloft promoted gas-to-particle conversion, leading to stronger particle growth at higher altitudes. As a result, higher particle concentrations accompanied by stronger hygroscopicity led to >20% higher NPF-induced cloud condensation nuclei (CCN) formation aloft. However, when vertical mixing was suppressed, gaseous pollutants tended to accumulate near the surface. These pollutants then contributed to particle growth at ground level, exacerbating atmospheric haze pollution near ground. This, in turn, further reduced the boundary layer height. The valuable results provided novel information of the interactions between boundary layer dynamics and new particle growth, enhancing our understanding on the climate and environmental effects of NPF.
1. Kulmala, M., et al., Direct Observations of Atmospheric Aerosol Nucleation. Science, 2013. 339(6122): p. 943-946.
2. Kerminen, V.-M., et al., Atmospheric new particle formation and growth: review of field observations. Environmental Research Letters, 2018. 13(10): p. 103003.
3. Stolzenburg, D., et al., Atmospheric nanoparticle growth. Reviews of Modern Physics, 2023. 95(4).
4. Du, W., et al., A 3D study on the amplification of regional haze and particle growth by local emissions. npj Climate and Atmospheric Science, 2021. 4(1): p. 1-8.
5. Du, W., et al., Impacts of enhanced new-particle growth events above urban roughness sublayer on cloud condensation nuclei. One Earth, 2024.
How to cite: Du, W., Sun, Y., Zhao, J., Dada, L., Wang, Y., Chen, X., Li, Z., Zhang, Y., Hu, F., Kokkonen, T., Kerminen, V.-M., and Kulmala, M.: Understanding the influence of particle growth on air quality and local climate in megacity, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12236, https://doi.org/10.5194/egusphere-egu25-12236, 2025.
This study investigates the role of wildfires in elevating ambient PM2.5 concentrations during droughts in California, U.S., from 2006 to 2020. While previous research has explored individual relationships between droughts, wildfires, and PM2.5 concentrations, a comprehensive analysis integrating all these components is lacking. This study employs a multi-tiered statistical approach to estimate each relationship among droughts, wildfires, and PM2.5 concentrations and to quantify the contribution of wildfires to the association between droughts and PM2.5 air pollution. During the study period, PM2.5 concentrations increased by 1.47 µg/m3 [standard error (SE)= 0.10] on average as drought conditions worsened by 1 unit of the Standardized Precipitation Evapotranspiration Index (SPEI). Drought-related PM2.5 increases were greater during wildfire days [3.29 µg/m3 (SE= 0.36)] than during non-wildfire days [0.97 µg/m3 (SE= 0.08)] per unit decrease in SPEI. During wildfire days, the drought-related PM2.5 increase substantially diminished from 3.29 µg/m3 (p< 0.0001) to -0.10 μg/m3 (p= 0.1307) after adjusting for wildfire-induced PM2.5 concentrations. Furthermore, the likelihood of PM2.5 exceedance days increased by 198% per unit decrease in SPEI due to wildfires during droughts. These findings demonstrate that the increase in drought-related PM2.5 concentrations is largely attributable to wildfire-induced PM2.5. Understanding the role of wildfires is crucial for air quality management and preparedness for future extreme events in the era of climate change.
How to cite: Lee, H. J., Shin, M. Y., and Kim, N. R.: A key role of wildfires in the association between droughts and PM2.5 air pollution, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6166, https://doi.org/10.5194/egusphere-egu25-6166, 2025.
Extreme weather becomes more frequent with global warming. The compound heatwave and drought (CHWD) events can intensify their individual environmental and societal impacts and cause disastrous threats. Abnormally high concentrations of surface ozone (O3), were usually observed during CHWD worldwide, while vegetation-atmosphere interactions further complicate the response of ozone to CHWD by influencing BVOC emissions and stomatal deposition processes. Using ERA5 data and major heatwave and drought indicators, the trend of heatwave and CHWD in summer in northern hemisphere during 1960-2023 was analyzed. We then used the online regional meteorology-chemistry model (WRF/Chem) to explore the effects of soil wilting point and dry deposition algorithms on the simulated vegetation-atmosphere feedback processes, as well as their impact on ozone pollution under CHWD. Results show that CHWD events have frequently engulfed many parts of the Northern Hemisphere, which is 3−5 times higher than in past decades. Under the influence of CHWD, more ozone pollution may be caused, especially in Europe, with a 35% increase in ozone concentrations during CHWD. The simulation results show that the increase of isoprene emission promoted the formation of ozone in CHWD summer, while the emission of isoprene is inhibited under drought conditions, mainly concentrated in the area with rich vegetation. Although the reduction of isoprene emissions during droughts inhibits ozone production, the ozone concentration of CHWD in summer is still higher, and high temperature plays a leading role. The wilting point from International Food Policy Research Institute (IFPRI) and Wesely-NoahMP dry deposition algorithms can more accurately describe the vegetation-atmosphere feedback process.
How to cite: lu, Y. and li, M.: Vegetation-atmosphere feedback during compound heatwave and drought aggravates the ozone pollution in northern Hemisphere, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2368, https://doi.org/10.5194/egusphere-egu25-2368, 2025.
Heatwaves, defined as prolonged periods of excessively hot weather, are increasingly recognized as a public threat due to their significant impact on human health and the environment. While the intrinsic impact of heatwaves on public health and the environment is well-recognised, a growing interest is emerging in the impact that these extreme weather events have on air pollution. Moreover, climate change has increased the frequency and intensity of these events raising concern about the potential impact on air pollution, and in particular on O3 levels. While the positive correlation between O3 and Temperature has been extensively analysed worldwide and in different time scales, the underpinning processes, their occurrence and their combination are still unclear. The summer of 2019 in the UK offers a compelling case study, as three distinct heatwave events occurred, characterized by record-breaking temperatures, including a peak of 38.7°C, and widespread O3 exceedances across both urban and rural areas. This study uses the WRF-Chem chemistry-transport model to simulate the entire summer of 2019, focusing on heatwave events and their influence on O3 formation. The analysis identifies key meteorological and chemical drivers, such as temperature, VOC emissions, and stagnation of air masses, which exacerbate O3 levels during the heat waves. The results indicate that the increased presence of biogenic isoprene played a significant role in O3 formation, particularly during heatwaves, with urban areas experiencing higher peaks due to a combination of temperature, emissions, and weak air movement. With the frequency and intensity of heatwaves increasing due to climate change, our findings underscore the importance of considering both anthropogenic and natural emissions in future air quality management to protect public health.
How to cite: Mazzeo, A. and Hossaini, R.: Chemical and meteorological drivers of Ozone extremes during the heatwave of summer 2019 in the UK. , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2810, https://doi.org/10.5194/egusphere-egu25-2810, 2025.
Biomass burning (BB) emission inventories are often used to understand the interactions of aerosols with weather and climate. However, large uncertainties exist among current BB inventories, so the choice of inventories can greatly affect model results. To quantify the differences among BB emission inventories and reveal their reasons, we compared carbon monoxide (CO) and organic carbon (OC) emissions from seven major BB regions globally from 2013 to 2016. The current inventories are based on two basic approaches: (1) bottom-up approach, which establishes inventories based on observed surface data, and (2) top-down approach, which based on the release rate of radiative energy from vegetation burning. In this study, we selected mainstream bottom-up inventories Fire INventory from NCAR 1.5 (FINN1.5) and Global Fire Emissions Database version 4s (GFED4s), and the top-down inventories Quick Fire Emissions Dataset 2.5 (QFED2.5) and VIIRS-based Fire Emission Inventory version 0 (VFEI0). We find that the total global CO emissions fluctuate between 252 and 336 Tg and the regional bias is even larger, which can be up to six times. Dry matter is responsible for most of the regional variation in CO emissions (50–80 %), with emission factors accounting for the remaining 20–50 %. Uncertainties in dry matter often come from biases in the calculation of bottom fuel consumption and burned area, which are closely related to vegetation classification methods and fire detection products. In the tropics, peatlands contribute more fuel loads and higher emission factors than grasslands. At high latitudes, as cloud fraction increases, the bias between burned area (or fire radiative power) increases by 20 %. In addition, due to the corrected emission factors in QFED2.5, global BB OC emissions have higher variability, fluctuating between 14.9 and 42.9 Tg.
Finally, we applied the four sets of BB emission inventories to the Community Atmosphere Model version 6 (CAM6) and compared the model results with observations. Our results suggest that the simulations based on the GFED4s agree best with the MOPITT-retrieved CO. We also compared the simulation results with satellite or ground-based measurments, such as Moderate Resolution Imaging Spectroradiometer (MODIS) AOD and AErosol RObotic NETwork (AERONET) AOD. Our results reveal that there is no global optimal choice for the BB inventories, but we give certain inventory recommendations based on different study areas and spatiotemporal scales. This study has implications for reducing the uncertainties in emissions or improving BB emission inventories in further studies.
How to cite: Lou, S., Hua, W., and Huang, X.: Diagnosing uncertainties in global biomass burning emission inventories and their impact on modeled air pollutants, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7871, https://doi.org/10.5194/egusphere-egu25-7871, 2025.
Air pollution is a high-profile issue that causes precipitation acidification, water pollution, and building corrosion, negatively affecting human respiratory health. As technology gradually digitalizes, the rise in electricity demand may exacerbate pollution, further impacting the environment and public health. The process of electricity generation emits significant amounts of air pollutants like SO₂, NOₓ, O₃, CO, PM₁₀, and PM₂.₅, which cause acid precipitation and smog that can potentially threaten public health. Among various methods of generating electricity, the thermal power-based method has the most significant impact on air pollution, accounting for 70% of the total, primarily through gas-fired and coal-fired power. To comprehend the environmental impact of electricity generation by the government-operated Taiwan Power Company, this study concentrates on identifying the relationship between electricity consumption, air pollutants, and hydro-meteorological factors. To achieve this aim, two data-driven methods are employed: (1) Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN), an improved version of Empirical Mode Decomposition (EMD), to extract long-term trends from non-stationary, non-linear data (2) Time-dependent Intrinsic Correlation (TDIC) to visualize and quantify the correlation, illustrating the degree of relationship between two time-series data sets. The CEEMDAN algorithm will decompose data into several Intrinsic Mode Functions (IMF) and one long-term trend of data. Those IMFs represent the changing data in different time scales. Subsequently, this research utilizes each IMF to reconstruct signals and generate wind rose diagrams. With the wind rose diagram, this research can analyze multi-scale distribution properties of wind direction and wind speed that can explore the changing trends of the wind field. By decoding these relationships, this research can better examine the degree of thermal power generation impacts on air pollution and how wind direction disperses air pollutants, providing a high-risk mapping to avoid human activities. Based on Taiwan's geographical address surrounded by the sea, this study can encompass the impacts of anthropogenic factors and natural factors, like monsoons, on air pollution, achieving a more comprehensive analysis. Moreover, integrating these findings and policy implementation enables more sustainable resource management and decision-making.
How to cite: Yao, S. T. and Tsai, C. W.: Analyzing the Environmental Impact of Thermal Power Plants on Air Pollution across Taiwan., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16683, https://doi.org/10.5194/egusphere-egu25-16683, 2025.
As pollution control efforts in China continue to deepen, the role of natural processes, such as vegetation emissions, in air pollution has become increasingly significant. Climate warming, coupled with the growing frequency of extreme weather events like high temperatures, droughts, and typhoon peripheries, intensifies the emission of biogenic volatile organic compounds (BVOCs) from vegetation. The interaction between natural emissions and urban anthropogenic pollutants contributes to the escalation of ozone photochemical pollution. This study aims to explore the relationship between BVOC emissions and ozone pollution at both climate and weather scales through numerical simulations. Additionally, leveraging large-scale environmental data and machine learning techniques, the research will investigate the drivers of isoprene emissions and their impact on urban air quality.
How to cite: Wang, N. and Yang, F.: Impact of extreme weather induced BOVCs on O3 formation in China, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7898, https://doi.org/10.5194/egusphere-egu25-7898, 2025.
The El Niño-Southern Oscillation (ENSO) significantly affects the interannual variability of tropospheric ozone, but the quantitative contributions from individual processes and how the ozone-ENSO response will change in the future remain unclear. In this study, we apply the GEOS-Chem global chemical transport models to quantify the contribution of transport, chemistry, and biomass burning to ozone variability in different ENSO phases, evaluate the ability of different climate-chemistry models (CCMs) in the Coupled Model Intercomparison Project Phase 6 (CMIP6) in capturing the present-day ozone-ENSO response, and examine the future changes in such response. GEOS-Chem model simulation over 2005-2020 largely reproduces the ozone-ENSO response observed by the Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) instrument, including the instantaneous decrease (increase) in tropospheric ozone column (TCO) over tropical eastern (western) Pacific in the El Niño phase, and the delayed responses (3-9 months lagged behind the Nino 3.4 index) in South America and Africa. The combined effects of transport, chemistry, and biomass burning emissions explain 94%~98% of the variability of TCO in tropical Pacific during ENSO. Changes in transport patterns dominate the overall tropospheric ozone-ENSO response, by increasing TCO by 0.8 DU (53% of the total variability) in western Pacific region and decreasing TCO by 2.2 DU (92%) in the eastern Pacific region during the El Niño condition relative to the normal periods. Changes in atmospheric temperature, water vapor, and cloud cover reduce ozone in the lower and middle troposphere (500-800 hPa) in the eastern Pacific by 2.0 ppbv, comparable to the transport induced ozone decrease of 3.8 ppbv. Biomass burning emissions cause an averaged ozone increase of 0.8 DU in Indonesia during El Niño and 0.7 DU in Brazil during La Niña. We find that five out of ten CCMs in CMIP6 can reproduce the historical ozone-ENSO response in 1980-2014. Interactive tropospheric chemistry and accurate representation of vertical circulation in ENSO phases are vital for the CCMs to capture the ozone-ENSO response. These models with successful skills consistently indicate that the ozone-ENSO response will increase by approximately 20% by the end of the 21st century, driven by the strengthening anomalous circulation and high water vapor concentration in ENSO phases in a warming climate. These results are critical for understanding climate-chemistry interactions and for improving future ozone projection.
How to cite: Li, J., Wang, H., Fan, Q., and Lu, X.: Tropospheric ozone responses to the El Niño-Southern Oscillation (ENSO): quantification of individual processes and future projections from multiple chemical models , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16719, https://doi.org/10.5194/egusphere-egu25-16719, 2025.
Surface ozone (SurfO3) pollution poses significant challenges to air quality, public health and agriculture worldwide. In a scenario of rising anthropogenic emissions, increasing temperature and altered atmospheric compositions exacerbate SurfO3 production in hotspots of pollution, leading to an ozone-climate penalty that could offset gains from emission reduction measures. This study explores projected changes in SurfO3 under the Aerosol and Chemistry Model Intercomparison Project (AerChemMIP) simulations of the Coupled Model Intercomparison Project phase-six (CMIP6), focusing on their implications for agriculture in India. We analyse the simulations from the United Kingdom Earth System Model version1 at low (-LL) resolution (UKESM 1-0-LL) and Geophysical Fluid Dynamics Laboratory Earth System Model version 4 (GFDL-ESM 4) models, following the anthropogenic emission trajectory of the shared socio-economic pathway (SSP)3–7.0 high emission scenario with pre-defined climate (SSP370pdSST) and changing climate (SSP370SST). Climate-induced increases in SurfO3 is observed in the rabi (December–February) and late-kharif (October–November) seasons, whereas early to mid-kharif (June–September) season show a reduction in SurfO3 in India. Increasing trend in climate change-induced SurfO3(0.03–0.08 ppbv yr-1) is evident in the Indo-Gangetic Plain (IGP), the ‛breadbasket of India’, during most seasons, and in central India during post-kharif and rabi seasons. This suggests that, even if the precursor emission remains at the current level, climate change alone could contribute to the increase in SurfO3 in the highly polluted regions of south Asia by 2050. Furthermore, the IGP region, one of the most fertile agricultural regions in South Asia, is likely to face significant challenges due to increasing SurfO3, which exacerbates crop yield losses, particularly for rabi wheat. This situation is concerning, as IGP comprises of about 27% of the total cultivated area and contributes significantly (about 50% of the total food consumed in the country) to the national agricultural production in India. Therefore, the study emphasise the need for targeted mitigation strategies, particularly for CH4, VOCs and NOx, to mitigate the dual challenges of climate change and SurfO3 pollution.
Keywords: Surface ozone, Climate change, AerChemMIP, Ozone-climate penalty, Agriculture, IGP
How to cite: Kunhimuthappan Suresan, A. and Kuttippurath, J.: Projected changes and implications of surface ozone pollution in India under changing climate and emission scenarios, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9896, https://doi.org/10.5194/egusphere-egu25-9896, 2025.
The North China Plain is one of the most heavily polluted regions in the world in terms of surface ozone pollution, and experiences frequent extreme summer heat waves. Concurrently, extreme heat events—capable of triggering severe ozone episodes—are becoming increasingly frequent, suggesting a growing challenge for ozone air quality control in a warming climate. In this study, we utilize the long-term surface measurements to show that, in the North China Plain, ozone-temperature relationship has two distinct regimes of ozone suppression (OS) vs. non-OS in June months, with a regime shift occurring around 2020. The observed OS can be well captured by the GEOS-Chem model and a machine learning model based on meteorological data only; our analysis indicates that OS is primarily driven by different circulation patterns rather than by the previously identified chemical and emissions processes. Furthermore, although the GEOS-Chem successfully captures the shift from OS to no-OS around 2020, the observed non-OS in NCP was strongly underestimated by the model. Using an improved version of GEOS-Chem, we quantify the potential importance of meteorological factors, changes in anthropogenic emissions, and chemical drivers. The results show that at extremely high temperatures, temperature-dependent emission processes such as soil NOx and anthropogenic VOCs contribute significantly to the ozone temperature slope during no-OS. Whereas the reduction of anthropogenic emissions is unfavorable for the occurrence of no-OS, the contribution of NOx-producing processes (e.g., PAN decomposition) is amplified at high temperatures due to a shift in ozone production control from NOx-limited to VOC-limited conditions.
How to cite: Yang, Z., Li, K., and Liao, H.: Complex Ozone-Temperature Relationship in the North China Plain Under Heat Extremes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10924, https://doi.org/10.5194/egusphere-egu25-10924, 2025.
Nitrogen oxides (NOx = NO + NO₂) are significant air pollutants that pose direct health risks and drive the formation of secondary pollutants such as ozone (O₃) and fine particulate matter (PM₂.₅). While NOx emissions have declined in regions like Europe and the United States (Schneider et al., 2015), the South Asia has experienced a sharp increases, exacerbating air quality challenges. Despite regulatory efforts to curb anthropogenic NOx emissions, the contribution of natural NOx sources, particularly lightning, remains poorly understood. This study explores the role of lightning-induced NOx (LNOx) in shaping the NOx budget and its implications for air quality across the Indian subcontinent.
Focusing on the pre-monsoon (March-May) season, when deep convective activity is at its peak, we analyzed high-resolution lightning data from the Lightning Imaging Sensor (LIS) to identify periods of intense activity. Using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), we simulated LNOx emissions by varying NO emissions per lightning flash (200–800 mol) to quantify its contribution accurately. Sensitivity experiments were conducted to isolate the impact of LNOx on atmospheric composition. Our results reveal that lightning significantly alters surface concentration of NO₂ and O₃. At lightning-strike locations, surface NO₂ levels increased by up to 0.5 ppb/day, though reductions of ~0.25 ppb were observed in certain areas due to complex chemical interactions. O3concentrations showed enhancements of up to 1.5 ppb/day, driven by NOx- fueled ozone production. Although, these numbers are small compared to anthropogenic contributions, it may have significant impacts on human exposure. Additionally, we observed a notable increase in hydroxyl radical (OH) concentrations across the atmosphere, highlighting the role of LNOx in modulating oxidative capacity. Stratosphere-troposphere exchange processes further influenced surface levels of NO₂, O₃, and OH.
As climate change intensifies deep convective activity, the contribution of LNOx to air quality is expected to grow. This study underscores the need to incorporate LNOx as a significant natural source in air quality models and policymaking efforts to develop effective strategies for mitigating air pollution in the region.
How to cite: Ghoshal Chowdhury, S., Ganguly, D., and Dey, S.: Unveiling the Impact of Lightning-induced NOx on Air Quality Over India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-597, https://doi.org/10.5194/egusphere-egu25-597, 2025.
PM2.5 pollution poses a serious threat to human health, making its mitigation a priority for policymakers. Over the last decade, air quality control measures have led to significant reductions in PM2.5 concentrations across China. However, meteorological changes driven by variations in the climate system can offset these effects and even exacerbate PM2.5 pollution. During the cold seasons (autumn and winter) of 2015-2017, PM2.5 pollution persisted in the Pearl River Delta (PRD), South China, despite rapid emission reductions both in the PRD and its upwind regions. This period coincided with a notable transition in ENSO state, from a very strong El Niño in 2015 to a weak-to-moderate La Niña in 2017. Through meteorological analysis and WRF/CMAQ simulations, this study investigates the connection between this climate transition and persisted PM2.5 pollution in the PRD. Comparisons of meteorological conditions during the three cold seasons align with previously reported El Niño and La Niña effects: Precipitation and polluted-day humidity reached the highest in the El Niño year (2015), while a northerly wind anomaly was observed in the La Niña year (2017). These meteorological changes weakened local PM2.5 production but enhanced PM2.5 transport to the PRD in the three cold seasons, as indicated by changing contributions to PM2.5 in the WRF/CMAQ simulations: The contributions of local emissions declined from 30% in 2015 to 22% in 2017, while the contributions of upwind emissions rose from 48% to 56%. Although emission reductions contributed to lower polluted-day PM2.5 concentration in the PRD by -5.7 µg/m3 in 2015-2016 and -2.7 µg/m3 in 2016-2017, this effect was outweighed by the influence of meteorological changes, which resulted in its reduction of -6.1 µg/m3 in 2015-2016 and increase of +10.7 µg/m3 in 2016-2017. Three-year changes in PM2.5 sulfate were mainly attributed to emission reduction in the upwind regions, while these in PM2.5 nitrate were linked to varying transport contributions under meteorological changes. This study indicates that to effectively mitigate PM2.5 pollution in the PRD, targeted strategies that focus on local or upwind emissions under varying meteorological conditions should be adopted.
Acknowledgement: This work was supported by the National Key Research and Development Program of China (grant No. 2018YFC0213204),the National Science and Technology Pillar Program of China (grant No. 2014BAC21B01), the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany´s Excellence Strategy (University Allowance, EXC 2077, University of Bremen) and co-funded DFG-NSFC Sino-German Air-Changes project (grant no. 448720203).
How to cite: Qu, K., Wang, X., Yan, Y., Jin, X., He, L.-Y., Huang, X.-F., Cai, X., Shen, J., Peng, Z., Xiao, T., Vrekoussis, M., Kanakidou, M., Brasseur, G., Daskalakis, N., Zeng, L., and Zhang, Y.: Why did PM2.5 pollution persist in the Pearl River Delta, South China during the El Niño–La Niña transition despite emission reductions?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8633, https://doi.org/10.5194/egusphere-egu25-8633, 2025.
Given the significant environmental and health risks associated with near-surface nitrogen dioxide (NO2), machine learning is frequently employed to estimate near-surface NO2 concentrations (SNO2) from satellite-derived tropospheric NO2 column densities (CNO2). However, data-driven methods often face challenges in explaining the complex relationships between these variables. In this study, the correlation between CNO2 and SNO2 is examined using vertical profile observations from China’s MAX-DOAS network. Cloud cover and air convection substantially weaken (R = −0.68) and strengthen (R = 0.71) the CNO2-SNO2 correlation, respectively. Meteorological factors dominate the correlation (R2 = 0.58), which is 31% stronger in northern regions than in the southwest. Additionally, anthropogenic emissions impact SNO2, while topographical features shape regional climate patterns. At the Chongqing site, the negative impacts of unfavorable meteorological conditions, high emissions, and basin topography lead to significant contrasts and delays in daily CNO2 and SNO2 variations. This study enhances understanding of the spatial and temporal dynamics and influencing mechanisms of CNO2 and SNO2, supporting improved air quality assessments and pollution exposure evaluations.
How to cite: Chang, B., Liu, H., Zhang, C., Xing, C., Tan, W., Li, Q., Ji, X., Hu, Q., and Liu, C.: Relating satellite NO2 tropospheric columns to near-surface concentrations: implications from ground-based MAX-DOAS NO2 vertical profile observations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3995, https://doi.org/10.5194/egusphere-egu25-3995, 2025.
Wildfires pose a substantial threat to human lives, destroy infrastructure, disrupt economic activity, and damage ecosystem services. Weather and climate conditions, including air temperature, humidity, wind, and precipitation, play crucial roles in determining the intensity and persistence of wildfires, as well as the dispersion and transport of smoke plumes. In turn, aerosols emitted from biomass burning are capable of influencing meteorology via aerosol-radiation interaction or aerosol-cloud interaction. However, there has been limited attention paid to the intricate interplay between smoke aerosol pollution, fire weather, and wildfire emissions. Our studies highlight the significance of synoptic-scale feedback in driving extreme wildfires across diverse fire-prone landscapes, including the United States, southeastern Asia, and even the Siberian region. We found that meteorological feedback induced by smoke aerosols can modify near-surface wind speed, air dryness, and rainfall and thus worsen air pollution by enhancing wildfire emissions and weakening dispersion. The intricate interactions among wildfires, smoke aerosol, and fire weather form a positive feedback loop that substantially increases air pollution exposure.
How to cite: Huang, X., Wang, Z., Ding, K., Xue, L., and Ding, A.: Air pollution-fire weather interaction in diverse regions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1752, https://doi.org/10.5194/egusphere-egu25-1752, 2025.
The co-polluted days by ozone (O3) and PM2.5 (particulate matter with an aerodynamic equivalent diameter of 2.5 μm or less) (O3–PM2.5PDs) were frequently observed in the Beijing–Tianjin–Hebei (BTH) region in warm seasons (April–October) of 2013–2020. We applied the 3-D global chemical transport model (GEOS- Chem) to investigate the chemical and physical characteristics of O3–PM2.5PDs by composited analyses of such days that were captured by both the observations and the model. Model results showed that, when O3–PM2.5PDs occurred, the concentrations of hydroxyl radical and total oxidant, sulfur oxidation ratio, and nitrogen oxidation ratio were all high, and the concentrations of sulfate at the surface were the highest among all pollution types. We also found unique features in vertical distributions of aerosols during O3–PM2.5PDs; concentrations of PM2.5 decreased with altitude near the surface but remained stable at 975–819 hPa. Process analyses showed that sec- ondary aerosols (nitrate, ammonium, and sulfate) had strong chemical productions at 913–819 hPa, which were then transported downward, resulting in the quite uniform vertical profiles at 975–819 hPa on O3–PM2.5PDs. The weather patterns for O3–PM2.5PDs were characterized by anomalous high-pressure system at 500 hPa as well as strong southerlies and high RH at 850 hPa. The latter resulted in the strong chemical productions around 850 hPa on O3–PM2.5PDs. The physical and chemical characteristics of O3–PM2.5PDs are quite different from those of polluted days by either O3 alone or PM2.5 alone and have important implications for air quality management.
How to cite: Dai, H. and Liao, H.: Composited analyses of the chemical and physical characteristics of co-polluted days by ozone and PM2.5 over 2013-2020 in the Beijing–Tianjin–Hebei region, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1769, https://doi.org/10.5194/egusphere-egu25-1769, 2025.
Brown carbon (BrC) has been recognized as an important light-absorbing carbonaceous aerosol, yet understanding of its influence on regional climate and air quality has been lacking, mainly due to the ignorance of regional coupled meteorology-chemistry models. Besides, assumptions about its emissions in previous explorations might cause large uncertainties in estimates. Here, we implemented a BrC module into the WRF-Chem model that considers source-dependent absorption and avoids uncertainties caused by assumptions about emission intensities. To our best knowledge, we made the first effort to consider BrC in a regional coupled model. We then applied the developed model to explore the impacts of BrC absorption on radiative forcing, regional climate, and air quality in East Asia. We found notable increases in aerosol absorption optical depth (AAOD) in areas with high OC concentrations. The most intense forcing of BrC absorption occurs in autumn over Southeast Asia, and values could reach around 4 W m–2. The intensified atmospheric absorption modified surface energy balance, resulting in subsequent declines in surface temperature, heat flux, boundary layer height, and turbulence exchanging rates. These changes in meteorological variables additionally modified near-surface dispersion and photochemical conditions, leading to changes of PM2.5 and O3 concentrations. These findings indicate that BrC could exert important influence in specific regions and time periods. A more in-depth understanding could be achieved later with the developed model.
How to cite: Gao, M. and Wang, F.: Brown Carbon in East Asia: Seasonality, Sources, and Influences on Regional Climate and Air Quality, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1921, https://doi.org/10.5194/egusphere-egu25-1921, 2025.
Dust aerosols are critical in global climate change and air quality. In the context of global warming, dust emissions are projected to increase in certain dry areas. Utilizing a 40-year dataset of dust records and reanalysis data, along with satellite aerosol products, this study investigates the driving effects of extreme weather conditions on dust emissions and the magnification of their adverse impacts across Eurasia. Analysis reveals an overall upward trend (averaging 0.9 days decade−1) in dust event frequency in Central East Asia over the past four decades, and a rapid increase (averaging 0.28 days yr−1) in dust event occurrences in Mongolia. The study elucidates the influence of key meteorological factors—such as high temperatures, strong winds, low precipitation levels, reduced soil moisture, and diminished NDVI index—on the frequency of dust events across various regions. Particularly, temperature is identified as the dominant driver of the abrupt escalation in dust frequency observed in Middle East (R=0.30), Mongolia between 1994 and 2003 (R=0.62), and northern China (R=0.51). The analysis further indicates a substantial rise of dust events associated with extreme high temperatures accompanied by droughts over the past 40 years. It was also observed that the meteorological conditions, downwind air pollutants, and aerosol optical depth anomalies for dust events compounded by extreme high temperatures and droughts were considerably higher than those for typical dust events. Generalized additive machine learning models was employed to validate the driving impact of extreme weather on Eurasian dust events and the exacerbation of their adverse effects. These findings underscore that the increasing frequency of extreme weather events due to climate warming significantly amplifies the climate impacts and health risks posed by dust aerosols.粉尘气溶胶对全球气候变化和空气质量至关重要。在全球变暖的背景下，预计某些干旱地区的粉尘排放量将增加。利用40年的沙尘记录和再分析数据集，以及卫星气溶胶产品，本研究调查了极端天气条件对欧亚大陆沙尘排放的驱动作用及其不利影响的放大。分析表明，近40年来，中亚地区沙尘事件频次总体呈上升趋势（平均0.9 d /年 −1 ），蒙古地区沙尘事件频次快速增加（平均0.28 d /年 −1 ）。研究阐明了高温、强风、低降水、土壤水分减少、NDVI指数降低等关键气象因素对不同区域沙尘事件发生频率的影响。特别是，温度被认为是中东（R=0.30）、蒙古（R=0.62）和中国北方（R=0.51）沙尘频率急剧上升的主要驱动因素。分析进一步表明，在过去40年里，与极端高温和干旱相关的沙尘事件大幅增加。在极端高温和干旱条件下，沙尘事件的气象条件、顺风空气污染物和气溶胶光学深度异常明显高于典型沙尘事件。采用广义加性机器学习模型验证了极端天气对欧亚沙尘事件的驱动作用及其不利影响的加剧。这些发现强调，气候变暖导致的极端天气事件日益频繁，大大放大了沙尘气溶胶造成的气候影响和健康风险。
How to cite: Wang, W. and Li, M.: Extreme heat and drought have amplified the adverse effects of dust events across Eurasia, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2322, https://doi.org/10.5194/egusphere-egu25-2322, 2025.
Biomass burning (BB) is one of the largest sources of trace gases and primary carbonaceous particles in the global troposphere, posing great impacts on air quality and regional climate. Accurate quantification of BB emissions is vital for assessing its environmental and climate impacts. However, there are still large uncertainties in current BB emission inventories due to poorly characterized emission rates under different combustion states. The fixed emission factor (EF) instead of varying EF associated with different combustion efficiencies may be the reason for the bias. Here, based on satellite-retrieved carbon dioxide (CO2) and carbon monoxide (CO), the modified combustion efficiency (MCE) is derived for fire-prone regions in Africa. The monthly and inter-annual variability of MCE shows a good correlation with meteorological variables such as relative humidity. Therefore, variable EF was established based on its statistical relationship with MCE for different fire-emitted species. Application of such MCE-dependent EF in the global climate-chemistry model can greatly improve the performance of wildfire smoke pollution during the fire season, indicated by an increase of 31% in aerosol optical depth (AOD) and a 50% reduction in normalized mean bias compared with AOD observations. The study elucidates the critical role of meteorology in BB emission estimates and highlights the importance of implementing a dynamic fire emission inventory in response to meteorological conditions.
How to cite: Fang, X. and Wang, Z.: Variation of Modified Combustion Efficiency and Its Impact on Biomass Burning Emission Estimation in Africa, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3433, https://doi.org/10.5194/egusphere-egu25-3433, 2025.
Tropopause chemical structure (TCS) is influenced by the stratosphere-troposphere exchange (STE) and plays a role in Earth’s climate. Yet, this role is still not fully resolved in East Asia where active STE and high anthropogenic emissions coexist. Using airborne measurements of trace gases including O3, CO and H2O, we reveal the variations in TCS during two consecutive cut-off lows (COL), an important trigger of STE. We demonstrate the important roles of two-way STE and long-range transport processes in delivering natural and anthropogenic signatures in the TCS. The former COL case shows a normal pattern of TCS, consisting of stratospheric and tropospheric air and mixture of them. The latter, as a novel type of STE, exhibits an anomalous and complex structure, due to the deep convective injection into stratospheric intrusions, and advection of remote marine air. The distinct mixture of stratospheric air and anthropogenic pollution alters the TCS, with a horizontal and vertical scale estimated to be 200 km and 1 km, respectively. Moreover, air of maritime origins is also identified there, which is convectively transported and strongly dehydrated during the long-range transport. Such a complex TCS can produce unique chemical environments modulating cloud physics and atmospheric radiation. From a climatological perspective, events of these anomalous airmasses are nonnegligible in terms of their frequency and chemical impact revealed by multi-year observations. These new insights advance our understanding of the mixing of natural and anthropogenic species that shapes the TCS in East Asia, and have implications for climate change.
How to cite: Chen, Z., Liu, J., Qie, X., Thouret, V., Bian, J., Li, D., Bai, Z., Xiao, X., Cheng, X., Yang, M., Shu, L., and Chen, J.: Convective injection into stratospheric intrusions alters tropopause chemical structure, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3923, https://doi.org/10.5194/egusphere-egu25-3923, 2025.
The Gobi Desert is a prominent dust source in Asia, where the dust storm is severe and features great interannual and seasonal variability. Previous studies have found land surface variation plausibly plays an important role in the occurrence and intensity of dust storms. However, the quantitative estimation and numerical description in current models are still limited. Here, a comprehensive study utilizing multiple observations and modeling methods to assess the influence of vegetation and snow on dust was conducted. We found that Gobi deserts exhibit substantial monthly and interannual variability in dust storms, which shows a close connection with vegetation and snow. To quantitatively understand the impact of vegetation and snow cover on dust emissions and also to better characterize such effects in numerical models, we introduced a high-resolution dynamic dust source function that incorporates the effects of vegetation and snow on erodibility. The new parameterization noticeably improved dust-related simulations, including aerosol optical thickness and PM10 concentrations, and provided insights into the distinct effects of vegetation and snow on dust emissions. This study sheds light on the effects of vegetation and snow on dust storms over the Gobi Desert, highlighting the importance of dynamic representation of time-varying surface properties in dust simulation.
How to cite: Hao, Y. and Huang, X.: Modeling the Effects of Vegetation and Snow on Dust Storm over the Gobi Desert, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3439, https://doi.org/10.5194/egusphere-egu25-3439, 2025.
Brown carbon (BrC), a certain type of organic carbon (OC) with light-absorbing ability at visible and near-ultraviolet spectrum, pays an important role in the Earth's radiation budget and atmospheric warming. It is primarily produced through the incomplete combustion of biomass and fossil fuels, as well as the formation of secondary organic aerosols. Recent laboratory and field studies have identified a class of BrC known as dark brown carbon which exhibits black carbon (BC)-like properties and strong absorbing ability, with k value between 0.2 to 0.4 in the visible spectrum. However, few modeling studies have taken dark brown carbon into account, leading to an underestimation of its direct radiative forcing on the climate system.
In this study, we utilized the global-regional nested transport model, the Aerosol and Atmospheric Chemistry Model of the Institute of Atmospheric Physics (IAP-AACM), to simulate global brown carbon distribution. Following previous studies, we classified brown carbon into four categories based on its absorptivity: very weak brown carbon, weak brown carbon, moderate brown carbon, and dark brown carbon. Using the mass ratio of BrC/OC in the published paper, we constructed emission inventories for anthropogenic and biomass burning from EDGAR_v8.1 and GFED_v4.1, respectively, and assigned each emission source to one of the four BrC categories based on its absorptive properties. The model simulations were performed at a 1° × 1° resolution for both winter and summer in 2022 by coupling physical and chemical modules including dry deposition, wet scavenging, secondary formation, and aging. Model results were compared with AERONET and satellite-based aerosol absorption optical depth (AAOD), showing reasonable agreement.
This research includes dark brown carbon from biomass burning and secondary BrC from aromatic secondary organic aerosol (SOA). The Volatility Basis Set (VBS) scheme was employed to simulate SOA formation. The results indicate that secondary BrC contributes approximately 2% ~ 8% to global BrC absorption. Dark brown carbon accounts for 2% ~ 14% BrC concentrations, but contributes 47% ~ 88% to global BrC absorption. These findings highlight the significant role of dark brown carbon in solar absorption and its potential impact on the Earth's radiative forcing.
How to cite: Jiang, Z. and Wang, Z.: Modeling Study on the spatiotemporal distribution of global atmospheric brown carbon, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4164, https://doi.org/10.5194/egusphere-egu25-4164, 2025.
Although China’s air quality has substantially improved in recent years due to the vigorous emissions reduction, the Beijing–Tianjin–Hebei (BTH) region, especially its central and southern plains at the eastern foot of the Taihang Mountains, has been the most polluted area in China, with persistent and severe haze in winter. Combining meteorology–chemistry coupled model simulations and multiple observations, this study explored the causes of several heavy haze events in this area in January 2017, focusing on local circulations related to mountain terrain. The study results showed that on the weather scale, the configuration of the upper, middle, and lower atmosphere provided favorable weather and water vapor transport conditions for the development of haze pollution. Under the weak weather-scale systems, local circulation played a dominant role in the regional distribution and extreme values of PM2.5. Influenced by the Taihang and Yanshan mountains, vertical circulations and wind convergence zone were formed between the plain and mountain slopes. The vertical distribution of pollutants strongly depended on the intensity and location of the circulation. The circulation with high intensity and low altitude was more unfavorable for the vertical and horizontal diffusion of near-surface pollutants. More importantly, we found that the aerosol–radiation interaction (ARI) significantly amplified the impacts of local vertical circulations on heavy haze by two mechanisms. First, the ARI strengthened the vertical circulations at the lower levels, with the zonal wind speeds increasing by 0.3–0.8m s−1. Meanwhile, the ARI could cause a substantial downward shift in the vertical circulations (∼100 m). Second, the ARI weakened the horizontal diffusion of pollutants by reducing the westerly winds and enhancing wind convergence and southerly winds. Under these two mechanisms, pollutants could only recirculate in a limited space. This superposition of the typical local circulation and the ARI eventually contributed to the accumulation of pollutants and the consequent deterioration of haze pollution in the region.
How to cite: Peng, Y., Wang, H., Zhang, X., Liu, Z., and Zhang, W.: Superimposed effects of typical local circulations and aerosol–radiation interaction on heavy haze, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4100, https://doi.org/10.5194/egusphere-egu25-4100, 2025.
Natural dust storms significantly contribute to air pollution by elevating atmospheric particle levels. These dust storms also influence atmospheric photochemical processes through surface reactions on dust particles. In this study, we conduct a quantitative analysis of the impact of dust aerosols on near ground ozone in China, integrating multiple observations with advanced modeling techniques. Our findings reveal a notable reduction in regional average ozone concentrations (1.8 – 12.0 ppbv) in 12 dust storm events during 2016 to 2023, compared to scenarios with minimal or no dust influence. The critical drivers of the ozone decline include interactions between dust aerosols and ozone, the relevant radicals and radiation, as well as adverse meteorological conditions. Among these factors, dust aerosols are estimated to account for 24±13% of the observed ozone reduction. Furthermore, heterogeneous removal pathways, such as the direct uptake of ozone and the adsorption of dinitrogen pentoxide (N₂O₅) and hydroperoxyl radicals (HO₂) by dust aerosols, are identified as the crucial mechanisms contributing to ozone depletion. These findings underscore the complex chemistry of dust-mediated processes, which profoundly influence tropospheric photochemical cycles and amplify ozone sensitivity in volatile organic compound (VOC)-limited atmospheric environments.
How to cite: Tang, K., Zhang, Y., Li, N., and Ge, X.: Asian dust storm performing the role in surface ozone reduction, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4618, https://doi.org/10.5194/egusphere-egu25-4618, 2025.
Ground-level ozone (O₃) pollution has become a critical environmental issue in coastal urban areas, driven by rapid global urbanization. Sea-land breeze (SLB) circulation plays a key role in this process. However, the combined effects of SLB and synoptic-scale weather systems on O₃ pollution remain poorly understood. Most existing studies focus on individual events or short-term periods, lacking a systematic analysis of how mesoscale SLB interacts with larger-scale weather patterns to influence O₃ concentrations.This study investigates the impacts of SLB on O₃ pollution in the Pearl River Delta (PRD), a densely populated coastal region in southern China. Using 28 years of observational data and ERA5 reanalysis datasets, we analyze the spatial and temporal variability of SLB and its interactions with synoptic-scale winds in shaping O₃ distributions. Additionally, a random forest model is applied to quantitatively assess the contributions of SLB to O₃ variations under different meteorological conditions.This research provides a systematic framework for understanding the mesoscale-synoptic coupling processes that drive O₃ pollution in coastal cities. The findings highlight the critical role of SLB in regulating regional air quality and offer a solid scientific basis for designing effective mitigation strategies in similar coastal urban regions worldwide.
How to cite: Liu, C., Wang, H., and Fan, S.: Impacts of Sea-Land Breeze on the Ozone Pollution under varied synoptic weather patterns in the Pearl River Delta, China, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4747, https://doi.org/10.5194/egusphere-egu25-4747, 2025.
Wildfires and dust storms are two major environmental hazards that significantly degrade air quality and pose severe risks to human health and ecosystems. These events often occur simultaneously, forming compound extreme events that can have amplified impacts compared to individual occurrences. This study aimed to investigate the mechanisms linking wildfires and dust pollution, analyze the spatiotemporal distribution and trends of their co-occurrence, and examine the global inequality in exposure to these compound events, all using a combination of satellite data, reanalysis datasets, and environmental variables.
We first explored the underlying mechanisms by which wildfires contribute to dust pollution. This included investigating how wildfires disturb vegetation and soil, and how changes in land cover interact with meteorological factors such as wind speed and direction to produce and transport dust. Using satellite-based aerosol optical depth (AOD) and dust optical depth (DOD) data (e.g., MODIS, IASI), as well as environmental variables such as soil moisture, vegetation cover, and wind data, we aimed to understand the physical and chemical processes that link wildfire activity to increased dust emissions.
The second part focused on analyzing the spatiotemporal distribution of the co-occurrence of wildfires and dust storms. We examined the geographical overlap of these events over recent decades, identifying regions where the co-occurrence of wildfires and dust storms is most frequent. By analyzing multi-year satellite and reanalysis data, we also explored interannual variations in the frequency of these compound events and assess how their co-occurrence has changed over time.
Finally, we investigated the global inequality in exposure to the combined air pollution resulting from co-occurring wildfires and dust storms. By mapping the spatial distribution of these compound events, we identified regions and populations that were disproportionately affected, particularly in areas with high vulnerability. We analyzed the exposure levels based on socioeconomic and demographic factors, highlighting how vulnerable populations in certain regions face a higher risk of respiratory and cardiovascular diseases due to these compounded pollution events. This part of the study aimed to shed light on the unequal burden of wildfire-dust compound events and provides insights into the need for targeted mitigation and health interventions.
Our study seeks to provide a comprehensive understanding of the interactions between wildfires and dust storms, and the compounded environmental and health impacts they have. The results will contribute to the development of effective mitigation strategies, improve public health outcomes, and inform policies aimed at reducing the exposure and risks associated with these extreme events.
How to cite: Yang, Q.: Unequal Environmental and Health Impacts of Co-occurring Wildfires and Dust Events: Mechanisms, Spatiotemporal Distribution, and Exposure Inequality, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4931, https://doi.org/10.5194/egusphere-egu25-4931, 2025.
Although air quality in China has improved substantially over recent years, haze pollution events still occur frequently, especially over the North China Plain (NCP). Previous studies showed that typhoons are conducive to regional pollution events in eastern China; however, the underlying mechanism and quantitative understanding of the typhoons' impact on haze pollution remain unclear there. Here, based on ground-based and satellite observations, reanalysis data, and model simmulations, we show that northward typhoons approaching China are essential for autumn haze pollution over NCP. Elevated relative humidity levels and enhanced pollution accumulation, caused by northward typlhoons and the corresponding high-pressure systems, are responsible for the pollution enhancements over NCP. Compared with episodes without typhoon influence,cities near Taihang and Yan Mountain suffer from heavier haze pollution when typhoons approach, with PM2.5 concentrations increasing from 87.1 to 106.4 ug m-3. More water vapor from the Yellow and Bohai Seas and pollutants from eastern China are transported to these cities by typhoon-induced southeasterly wind anomalies, facilitating the chemical formation of aerosols there. In addition, by the block of mountains, these southeasterly wind anomalies also lead to stronger local accumulation over cities and an elevation of pollutants along themountains. What is more, with the implementation of emission reduction, the relative changes of PM2.5 concentrations between typhoon-induced episodes and no-typhoon episodes increase. This work highlights the importance of understanding the impact of synoptical weather on PM2.5 transport, accumulation, and formation processes in haze pollution mitigation in eastern China.
How to cite: Ding, K. and Lin, H.: Impacts of northward typhoons on autumn haze pollution over North China Plain, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5542, https://doi.org/10.5194/egusphere-egu25-5542, 2025.
Brown carbon (BrC) from anthropogenic activities and wildfires significantly impacts atmospheric processes through its sunlight absorption properties. This study aims to constrain the understanding of BrC's light absorption using multiple observations and models, providing a comprehensive assessment of its environmental implications. Anthropogenic sources and wildfires release BrC with distinct characteristics, influencing regional and global aerosol optical properties. By integrating field measurements, laboratory analyses, satellite products, and climate models, this research quantifies BrC's absorption across different spectral ranges and evaluates its contribution to radiative forcing. The results highlight the need for refined models to accurately represent BrC's complex behavior and improve predictions of its impacts on climate and air quality. This abstract presents the methodology, findings, and future directions for constraining BrC's sunlight absorption.
How to cite: Lin, G.: Constraining Sunlight Absorption of BrC from Anthropogenic Sources and Wildfires with Multiple-type Observations and Models, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7557, https://doi.org/10.5194/egusphere-egu25-7557, 2025.
The paper presents the air pollutant measurements and the spatial variation of air pollutants in Lhasa to reflect the characteristics of the air pollutants in a typical high-altitude city. According to the research, five-year measurements of air pollutants at 6 sites in Lhasa, were analyzed from January 2013 to December 2017. Within this period, the average pollutant concentration was highest for O3, at about 65.24 μg/m3, followed by PM10, with an average of 58μg/m3. The lowest concentration was found for SO2, with an average of 9.258 μg/m3; additionally, the concentrations of surface ozone were higher in spring (100.73μg/m3) than in winter (49.00μg/m3). O3 concentrations are greater in the spring and summer and clearly peaked at 12 and 6 PM. The NOx concentration peaked in the winter and rise sharply between 9:00-11:00 and 22:00-01:00.Air pollutants at all the 6 sites in Lhasa generally displayed similar patterns of both diurnal and monthly variations, indicating the mixed atmospheric environment and the overall effect of the meteorological conditions in the city.
The air quality in Lhasa is better than in other Chinese provincial capitals because it has lower concentrations of all air pollutants except O3. The vegetation index is also one of the key factors affecting the concentration of pollutants. The highest correlation with the vegetation index was found to be with PM10 (-0.91), followed by PM2.5 and SO2, with correlation coefficients of -0.74 and -0.68, respectively. The vegetation index has a strong impact on the pollutants in Lhasa city, and areas with sparse vegetation and a dry climate usually result in higher atmospheric ozone loads. We suggested that underscoring the need for targeted interventions to enhance green spaces and mitigate the adverse effects of climate on air quality.
How to cite: Zhuoga, D., Jun, D., Duo, B., and Zhuoma, L.: Pollution characteristics of ozone and atmospheric particulate matter during 2013-2017 associated with meteorological factors in Lhasa, Tibet, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12257, https://doi.org/10.5194/egusphere-egu25-12257, 2025.
Atmospheric conditions show significant variations during cyclone advancement and landfall in tropical regions. Here, we investigate the unusual fog event over the Kerala region associated with the Mandous cyclone (December 6-10, 2022) in the Bay of Bengal (BoB). This study also investigates the variations in atmospheric aerosol loading and its potential source identification. Before the landfall of cyclone Mandous, there was a significant increase in aerosol concentration over the Kerala region. Changes in prevailing wind patterns due to BoB cyclones lead to long-range transport of aerosols from the Indo-Gangetic Plain (IGP) and Rajasthan region to the South Indian region. The changes in meteorological parameters during these days are analyzed. Previous studies reported increased aerosol concentration during cyclone formation, but such events still need to be reported in the Kerala region. Unusual fog events in the Kerala region are associated with this increased aerosol loading. From the HYSPLIT back trajectory analysis, it is evident that particulate matter (PM2.5) has been brought to the Kerala region from multiple places in South Asia during these days. The IGP region contributes the majority of the transported aerosols. The average PM2.5 mass concentration over the Kerala region shows a sharp increase during these days. Mandous form in winter (December), and the PBL height is low during this season. From analysis, it is clear that all meteorological parameters favor fog formation. The increased loading of atmospheric aerosol and moisture to the Kerala region during the study period was associated with the formation of the Mandous cyclone. Low ventilation coefficient values imply less vertical mixing and a stable atmosphere. So, these conditions lead to the observed abnormal fog events over the Kerala region. This kind of event is rare in South Indian regions but significantly impacts air quality and human health. Large-scale transport during cyclones increases the concentration of PM2.5 in the south Indian region, leading to a poor Air Quality Index (AQI), significantly affecting human health.
How to cite: Arun, K., Manoj, M. G., Ahana, K., and Satheesan, K.: Role of Bay of Bengal cyclone in unusual aerosol loading and fog events over the Kerala regions, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17363, https://doi.org/10.5194/egusphere-egu25-17363, 2025.
Posters virtual: Wed, 30 Apr, 14:00–15:45 | vPoster spot 5
EGU25-11612 | Posters virtual | VPS3
Enhancing the Simulation and Prediction of Extreme Temperature and Water Vapor in a Warming Climate Using a High-Resolution Earth System ModelWed, 30 Apr, 14:00–15:45 (CEST) | vP5.11
Extreme weather events, such as extreme temperatures, water vapor transport, and the resulting extreme precipitation, have been occurring with increasing frequency and are projected to intensify further in a warming climate. Understanding how these events respond to climate change is critically important. Numerical models serve as essential tools for uncovering the mechanisms behind these phenomena, with spatial resolution being one of the key challenges. Leveraging advanced supercomputing resources, we have recently made significant advancements in developing high-resolution Earth system models based on the Community Earth System Model (CESM), featuring a 25 km atmospheric resolution and a 10 km oceanic resolution. Compared to the commonly used CMIP5 and CMIP6 models, the high-resolution Earth system model demonstrates substantial improvements in reproducing extreme weather events, thereby greatly enhancing the confidence in future projections.
How to cite: Gao, Y.: Enhancing the Simulation and Prediction of Extreme Temperature and Water Vapor in a Warming Climate Using a High-Resolution Earth System Model, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11612, https://doi.org/10.5194/egusphere-egu25-11612, 2025.
