ITS3.12/AS2.10

Aerosol transport processes in the Southern Hemisphere (SH) have been the center of renewed attention in the last two decades because of a number of major geophysical events such as volcanic eruptions (Chile and Argentina), biomass burning (Australia and Chile) and dust storms (Australia and Argentina).

While volcanic and fire activity in the SH have been the focus of several studies, there is a dearth of satellite assessments of dust activity. The lack of such analysis impairs the understanding of biological processes in the Southern Ocean and of the provenance of dust found in snow at the surface of East Antarctica.

This presentation will show an analysis of time series of Aerosol Optical Depths over the Patagonia desert in South America. Data from two aerosol algorithms (Dark Target and Deep Blue) will be jointly analyzed to establish a timeline of dust activity in the region. Also, dust proxies from both algorithms will be compared with ground-based observations of visibility at different airports in the area. Once an understanding of frequency and time evolution of the dust activity is achieved, first estimations of ocean-going dust fluxes will be derived.

How to cite: Gassó, S., Gupta, P., Ginoux, P., and Levy, R.: Preliminary results of the first assessment of 20 years of dust activity in the Patagonia desert (South America) with aerosol products from the MODIS sensors, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7805, https://doi.org/10.5194/egusphere-egu21-7805, 2021.

Saharan dust has an impact on the atmospheric environment and sedimentary units in distant regions. Although Iceland is located within one of the main atmospheric dust pathways moving towards the Arctic, no evidence of Saharan dust deposition has been provided to date for the region. Here we present the results of fourteen Saharan dust episodes, which were identified in Iceland between 2008 to 2020. Aerosol optical depth data of Terra MODIS, HYSPLIT backward trajectories and numerical simulations of Barcelona Supercomputing Center were used in this work to identify the dust episodes. 
Grain size and shape of the Saharan mineral material deposited in Iceland during two severe deposition events were investigated in detail. Icelandic dust samples from the most active local dust sources were compared with samples of deposited mineral dust from these two severe Saharan dust events to determine their granulometric (complex grain size and shape parameters) and mineralogical characteristics. An automated static optical image analysis technique was applied to thousands of individual particles, and was completed by Raman spectroscopy to identify external quartz particles. 
Saharan dust episodes were associated with enhanced meridional atmospheric flow patterns driven by unusual meandering jets. Strong southerly winds were able to carry large Saharan quartz particles (> 100 µm) towards Iceland. Our results confirm the atmospheric pathways of Saharan dust towards the Arctic, and identify new pathways of giant Saharan dust particles in the study region, including the first evidence of their deposition in Iceland as previously predicted by models.
The support of the National Research, Development, and Innovation Office (projects NKFIH KH130337 and K120620 (for G. Varga)), Czech Science Foundation (project No. 20-06168Y (for P. Dagsson-Waldhauserova)), and COST inDust Action are gratefully acknowledged.

How to cite: Varga, G., Dagsson-Walhauserová, P., Gresina, F., and Helgadottir, A.: Saharan dust episodes and giant quartz particles in Iceland, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11113, https://doi.org/10.5194/egusphere-egu21-11113, 2021.

Carbonaceous matter, including organic carbon (OC) and black carbon (BC), is an important climate forcing agent and contributes to glacier retreat in the Himalayas and the Tibetan Plateau (HTP). The HTP - the so-called “Third Pole” – contains the most extensive glacial area outside of the polar regions. Considerable research on carbonaceous matter in the HTP has been conducted, although this research has been challenging due to the complex terrain and strong spatiotemporal heterogeneity of carbonaceous matter in the HTP. A comprehensive investigation of published atmospheric and snow data for HTP carbonaceous matter concentration, deposition and light absorption is presented, including how these factors vary with time and other parameters. Carbonaceous matter concentrations in the atmosphere and glaciers of the HTP are found to be low. Analysis of water-insoluable organic carbon and BC from snowpits reveals that concentrations of OC and BC in the atmosphere and glacier samples in arid regions of the HTP may be overestimated due to contributions from inorganic carbon in mineral dust. Due to the remote nature of the HTP, carbonaceous matter found in the HTP has generally been transported from outside the HTP (e.g., South Asia), although local HTP emissions may also be important at some sites. This study provides essential data and a synthesis of current thinking for studies on atmospheric transport modeling and radiative forcing of carbonaceous matter in the HTP.

How to cite: Li, C., Yan, F., and kang, S.: Carbonaceous Matter in the Atmosphere and Glaciers of the Himalayas and the Tibetan Plateau: An Investigative Review, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1687, https://doi.org/10.5194/egusphere-egu21-1687, 2021.

The report highlights the results of first ice-core palynology studies from the Elbrus Western Plateau. The title of the highest point in Europe and the geographical location of Elbrus determine the diversity of natural conditions and, as a result, palynological spectra, which act as markers of seasonal vegetation, climate dynamics, fires and anthropogenic activities in the Mediterranean, southern European Russia, the Middle East, and North Africa.

The 24-m ice core from the Elbrus Western Plateau collected in 2017 (5115 m a.s.l., 43^о20′53,9′′ N, 42^о25′36′′ E) covers the period 2012-2017. Pollen analysis revealed a significant number of biological markers contained in the ice core, including pollen and spores, fungi, algae, testate amoebae, feather barbules, microcharcoal, and black carbon.

The obtained results show that taxonomic diversity and concentration of biomarkers in the ice core were determined by the seasons of the year and their inherent convective flows. Pollen assemblages are characterized by predominance of native Caucasian plant species. Among them pollen values of Picea forming the high-altitude forest belt in the Western Caucasus significantly exceed pollen frequency of Pinus growing near the upper timber line on Elbrus Mt in the Central Caucasus that suggests a westerlies of air masses and transfer of microparticles. A high abundance of non-pollen palynomorphs in pollen assemblages demonstrates a high potential for studying of human impact on mountain ecosystems. The first pollen data from the ice core evidences a promising resource of the high-altitude temperate glaciers as a flexible tool for atmospheric monitoring of microparticle transfer and fixing its seasonality and biotic relationships.

This work was supported by the Russian Science Foundation, project № 17-17-01270.

How to cite: Batalova, V., Mikhalenko, V., Kutuzov, S., Shumilovskikh, L., and Shukurov, K.: Modern atmospheric monitoring using pollen analysis of ice cores: a case study from the Elbrus Western Plateau, Caucasus, Russia, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8202, https://doi.org/10.5194/egusphere-egu21-8202, 2021.

By darkening the snow surface, mineral dust and black carbon (BC) deposition accelerate snowmelt and triggers numerous feedbacks. Assessments of their long-term impact at the regional scale are still largely missing despite the environmental and socio-economic implications of snow cover changes. Using detailed snowpack simulations, we show that dust and BC deposition advance snowmelt by 17 days on average in the French Alps and the Pyrenees over the 1979-2018 period, with major implications for water availability and ground temperature. The effect of BC compared to dust is generally prevailing except in the Southern Pyrenees more exposed to Saharan dust events. We also quantify a contribution of BC and dust deposition up to 30% to the variance of the snow melt-out date. Lastly, we demonstrate that the decrease in BC deposition since the 80's alleviated the impact of current warming on snow cover decline. Therefore, this study highlights the importance of accounting for the inter-annual fluctuations in light absorbing particles deposition to improve the accuracy of snow cover reanalyses and climate projections.

How to cite: Réveillet, M., Dumont, M., Gascoin, S., Lafaysse, M., Nabat, P., Ribes, A., Nheili, R., Tuzet, F., Menegoz, M., and Ginoux, P.: Modulation of the snow cover changes in the French Alps and the Pyrenees by the deposition of light absorbing particles over the last 40 years, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10657, https://doi.org/10.5194/egusphere-egu21-10657, 2021.

Revealing background concentrations of chemical elements and radionuclides in the surface components of the environment exposed to constant atmospheric processes is the first step towards detecting areas with their abnormally high concentrations of natural and man-made character. In this work, we present the results of studying the content of trace elements and microparticles in the snow cover accumulated during the 2018-2019 winter season in the Novy Urengoy region. Samples were taken along the roads using a rare sampling grid over the entire depth of the snow cover. In laboratory conditions, after the snow melted, the solution was filtered. The results of mass spectrometric measurements of the trace element concentrations in the filtrates show that their composition is homogeneous and does not vary slightly at the sampling points. Evaluation of the prevailing directions of backward air-mass trajectories was computed using the HYSPLIT model.

This work was supported by the Russian Science Foundation grant (project No 18-77-10039). Analytical studies were carried out at the Center for multi-elemental and isotope research SB RAS.

How to cite: Belyanin, D., Vosel, Y., Mezina, K., Melgunov, M., and Dobretsov, V.: The trace elements in the snow cover of the 2018-2019 season in the Novy Urengoy region (Arctic part of Western Siberia), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15763, https://doi.org/10.5194/egusphere-egu21-15763, 2021.

The configuration of the Santiago basin, Chile (33.5°S 70.65°W) is quite unique in that it combines very strong emissions of urban anthropogenic pollutants with the steep topography of the coastal and Andes cordilleras surrounding the Metropolitan area. Interactions between atmospheric pollution and mountain meteorology are therefore exacerbated, and the potential for black carbon (BC) deposition on glaciers is strong. Based on chemistry-transport modeling with WRF-CHIMERE, we investigate (i) the pathways leading to deposition of BC from Santiago up to Andean glaciers in wintertime and (ii) the differences in magnitude and time dynamics of such deposition between wintertime and summertime.

Ice and snow in the central Andes contain significant amounts of BC often attributed to emissions from Santiago. However, given the usually stable conditions in wintertime and the height of the obstacle to overcome for urban air masses (Santiago is 500 m a.s.l., summits are above 4000 m a.s.l.) the pathways for such deposition are not straightforward. We find that, for a typical winter month, up to 40% of BC dry deposition on snow- or ice-covered areas in the central Andes directly downwind from the Metropolitan area can indeed be attributed to emissions from Santiago. The adjacent network of canyons plays a key role in this export: for the case of the Maipo canyon, polluted urban air masses follow gentle slopes upward in the afternoon, consistently with mountain-valley circulation, before being vertically exported when reaching the tip of the main canyon. Statistical analysis shows that zonal wind speed in the urban area and vertical diffusion deep into the canyon account for most of the variance in BC deposition.

In summertime, more intense convection takes place, and mountain-valley circulation is seldom perturbed by cloud cover, resulting in a greater export potential. Accordingly, summertime dry deposition of BC on glaciers occurs on a regular basis with equivalent amounts each day, contrarily to a more chaotic time series in wintertime. The contribution of wet deposition in winter (nonexistent in summer) exacerbates this irregularity. However, as a consequence of weaker emissions, average monthly dry deposition of BC over the central Andes glaciers (29°S to 38°S) is found to be less than half in summertime (135 µg/m²) compared to wintertime (320 µg/m²). Given the lesser role played by wood burning for residential heating in summertime, emissions from Santiago through traffic and industry dominate the signal leading to 55% of dry deposition, while it accounts for only 14% in wintertime, at the regional scale, due to more scattered sources.

How to cite: Lapere, R., Mailler, S., Menut, L., and Huneeus, N.: Mountain-valley circulation in central Chile: consequences for Black Carbon deposition over glaciers in wintertime and summertime, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-482, https://doi.org/10.5194/egusphere-egu21-482, 2021.

Black carbon (BC) and organic carbon (OC, including brown carbon BrC) aerosols in the atmosphere, and their wet and dry deposition, are important for their climatic and cryospheric effects. Seemingly small amounts of BC in snow, of the order of 10–100 parts per billion by mass (ppb), have been shown to decrease its albedo by 1–5 %. Due to the albedo-feedback mechanism, surface darkening accelerates snow and ice melt. In snow, the temporal variability of light absorbing aerosols, such as BC, depends both on atmospheric and cryospheric processes, mostly on sources and atmospheric transport, and dry and wet deposition processes, as well as post-depositional snow processes.

We started a new research activity on BC and OC wet and dry deposition at Helsinki Kumpula SMEAR III station (60°12 N, 24°57 E, Station for Measuring Ecosystem-Atmosphere Relations, https://www.atm.helsinki.fi/SMEAR/index.php/smear-iii). The work included winter, spring, summer and autumn deposition samples during January 2019 - June 2020 (sampling is currently on hold). In winter, wet deposition consisted of snowfall and rainwater samples. Dry deposition samples were separately collected in 2020. For sample collection, a custom-made device, including a heating-system, was applied. The samples were analyzed using the OCEC analyzer of the Finnish Meteorological Institute’s aerosol laboratory, Helsinki, Finland. The special features in our deposition data are: 

• seasonal BC, OC, and TC (total carbon, the sum of BC and OC) deposition data for an urban background station at 60 ^oN
• precipitation received as either water or snow  
• dry deposition samples included (only in 2020)
• data as wet and dry deposition rates [concentration/time/area]
• simultaneous atmospheric measurements of the SMEAR III station

Since our deposition samples are collected manually, the data are non-continuous, yet they allow us to provide deposition rates. Such data can be utilized in various modeling approaches including, for example, climate and long-range transport and deposition modeling. According to our knowledge, these data are the first BC (determined as elemental carbon, EC), OC and TC wet and dry deposition data to represent Finland. Our sampling location, north of 60 deg. N, can be useful for other high-latitude studies and Arctic assessments, too.

Acknowledgements. We gratefully acknowledge support from the Academy of Finland NABCEA-project of Novel Assessment of Black Carbon in the Eurasian Arctic (no. 296302) and the Academy of Finland Flagship funding (grant no. 337552).

How to cite: Meinander, O., Heikkinen, E., Svensson, J., Aurela, M., Virkkula, A., Vestenius, M., and Hyvärinen, A.: Seasonal variations in black and organic carbon wet and dry deposition rates at SMEAR III station (60oN), Finland, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5362, https://doi.org/10.5194/egusphere-egu21-5362, 2021.

The snow-covered mountains of Himalayas are known to play a crucial role in the hydrology of South Asia and are known as the “Asian water tower”. Despite the high elevations, the transport of anthropogenic aerosols from south Asia and desert dust from west Asia plays a significant role in directly and indirectly perturbing the radiation balance and hydrological cycle over the region. Absorbing aerosols like black carbon (BC) and dust deposited on the snow surface reduces the albedo of the Himalayan snow significantly (snow darkening or snow albedo effect). Using a Regional Climate Model (RegCM-4.6.0) coupled with SNow, ICe and Aerosol Radiation (SNICAR) module, the implications of aerosol-induced snow darkening on the regional hydroclimate of the Himalayas are investigated in this study. The aerosols deposited on snow shows a distinct regional heterogeneity. The albedo reduction due to aerosols shows a west to east gradient during pre-monsoon season and this results in the positive radiative effect of about 29 Wm^-2, 17 Wm^-2 and 5 Wm^-2 over western, central and eastern Himalayas respectively. The reduction in the snow albedo also results in the sign reversal of the aerosol direct radiative effect i.e., from warming to cooling at the top of the atmosphere during pre-monsoon season. The excess solar energy trapped at the surface due to snow darkening warms the surface (0.66-1.9 K) and thus decreases the snow cover extent significantly. This results in the reduction of the number of snow-covered days by more than a month over the western Himalayas and about 10 – 15 days over the central Himalayas. The early snowmelt due to aerosol-induced snow darkening results in the increase of runoff throughout the melting season. Therefore, the present study highlights the heterogeneous response of aerosol induced snow albedo feedbacks over the Himalayan region and its impact on the snowpack and hydrology, which has further implications on the freshwater availability over the region.

How to cite: Nair, V. S., Keshav Hasyagar, U., and Babu, S. N. S.: Implications of aerosol-induced snow darkening on regional hydroclimate over the Himalayas, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11972, https://doi.org/10.5194/egusphere-egu21-11972, 2021.

High Latitude Dust (HLD) contributes 5% to the global dust budget and active HLD sources cover > 500,000 km². In Iceland, desert areas cover about 44,000 km², but the hyperactive dust hot spots of area < 1,000 km² are the most dust productive sources. For example Hagavatn dust source of area about 10 km² is captured on satellite images to produce visible dust plumes exceeding distance of > 700 km.

Recent studies have shown that Icelandic dust travelled about 2,000 km to Svalbard (Moroni et al., 2018) and about 3,500 km to Balkan Peninsula (Djordjevic et al., 2019). It estimated that about 7% of Icelandic dust can reach the high Arctic (N>80°). Previous study on Icelandic dust travelling about 1,300 km to Ireland (Ovadnevaite et al., 2009) serves as a case study to identify additional dust events arriving to Mace Head, Ireland in 2018-2020. In situ dust concentrations in Iceland, remote sensing and dust forecasts based on atmospheric-dust model DREAM (Dust REgional Atmospheric Model, https://sds-was.aemet.es/forecast-products/dust-forecasts/icelandic-dust-forecast) are used for this study.        

Reference:

Đorđević D., et al. 2019. Can Volcanic Dust Suspended From Surface Soil and Deserts of Iceland Be Transferred to Central Balkan Similarly to African Dust (Sahara)? Frontiers in Earth Sciences 7, 142-154.

Moroni B., et al. 2018. Mineralogical and chemical records of Icelandic dust sources upon Ny-Ålesund (Svalbard Islands). Frontiers in Earth Science  6, 187-219.

Ovadnevaite J., Ceburnis D., et al. 2009. Volcanic sulphate and arctic dust plumes over the North Atlantic Ocean. Atmospheric Environment 43, 4968-4974.

Additional studies on Icelandic dust: https://icedustblog.wordpress.com/publications/

How to cite: Dagsson-Waldhauserova, P., Burdova, N., Nickovic, S., Cvetkovic, B., Arnalds, O., Moroni, B., Djordjevic, D., and Ceburnis, D.: Long-range transport of Icelandic dust towards Europe and Arctic, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13306, https://doi.org/10.5194/egusphere-egu21-13306, 2021.