Role of Saharan dust and black carbon deposition on snow cover in the French mountain ranges over the last 39 years.

2020 ◽  
Author(s):  
Marion Réveillet ◽  
Marie Dumont ◽  
Simon Gascoin ◽  
Pierre Nabat ◽  
Matthieu Lafaysse ◽  
...  
Keyword(s):  
Snow Cover ◽  
Black Carbon ◽  
Carbon Deposition ◽  
Mineral Dust ◽  
Explicit Representation ◽  
Dust Deposition ◽  
Mountain Ranges ◽  
Annual Variability ◽  
Snow Cover Duration ◽  
The Impact

<p>Light absorbing particles such as black carbon(BC) or mineral dust are known to darken the snow surface when deposited on the snow cover and amplify several snow-albedo feedbacks, drastically modifying the snowpack evolution and the snow cover duration. Mineral dust deposition on snow is generally more variablein time than black carbon deposition and can exhibit both a high inter and intra annual variability. In France, the Alps and the Pyrenees mountain ranges are affected by large dust deposition events originating from the Sahara . The aim of this study is to quantify the impact of these impurities on the snow cover variability over the last 39 years (1979-2018).</p><p>For that purpose, the detailed snowpack model Crocus with an explicit representation of impurities is forced by SAFRAN meteorological reanalysis and a downscaling of the simulated deposition fluxes from a regional climate model (ALADIN-Climate). Different simulations are performed: (i) considering dust and/or BC (i.e. explicit representation), (ii) without impurities and (iii) considering an implicit representation (i.e. empirical parameterization based on a decreasing law of the albebo with snow age).</p><p>Simulations are compared at point scale to the snow depth measured at more than 200 Meteo-France’s stations in each massif, and spatially evaluated over the 2000-2018 period in comparing thesnow cover area, snow cover duration and the Jacard index to MODIS snow products. Scores are generally better when considering the explicit representation of the impurities than when using the snow age as a proxy for light absorbing particles content.</p><p>Results indicate that dust and BC have a significant impact on the snow cover duration with strong variations in the magnitude of the impact from one year to another and from one location to another.We also investigate the contribution of light absorbing particles depositionto snow cover inter-annual variability based on statistical approaches.</p>

scholarly journals Snow cover sensitivity to black carbon deposition in the Himalayas: from atmospheric and ice core measurements to regional climate simulations

2014 ◽  
Vol 14 (8) ◽  
pp. 4237-4249 ◽  
Author(s):  
M. Ménégoz ◽  
G. Krinner ◽  
Y. Balkanski ◽  
O. Boucher ◽  
A. Cozic ◽  
...  
Keyword(s):  
Snow Cover ◽  
Black Carbon ◽  
Regional Climate ◽  
Ice Core ◽  
Ice Cores ◽  
Short Wave ◽  
Wave Radiation ◽  
The Tibetan Plateau ◽  
Snow Cover Duration ◽  
The Impact

Abstract. We applied a climate-chemistry global model to evaluate the impact of black carbon (BC) deposition on the Himalayan snow cover from 1998 to 2008. Using a stretched grid with a resolution of 50 km over this complex topography, the model reproduces reasonably well the remotely sensed observations of the snow cover duration. Similar to observations, modelled atmospheric BC concentrations in the central Himalayas reach a minimum during the monsoon and a maximum during the post- and pre-monsoon periods. Comparing the simulated BC concentrations in the snow with observations is more challenging because of their high spatial variability and complex vertical distribution. We simulated spring BC concentrations in surface snow varying from tens to hundreds of μg kg−1, higher by one to two orders of magnitude than those observed in ice cores extracted from central Himalayan glaciers at high elevations (>6000 m a.s.l.), but typical for seasonal snow cover sampled in middle elevation regions (<6000 m a.s.l.). In these areas, we estimate that both wet and dry BC depositions affect the Himalayan snow cover reducing its annual duration by 1 to 8 days. In our simulations, the effect of anthropogenic BC deposition on snow is quite low over the Tibetan Plateau because this area is only sparsely snow covered. However, the impact becomes larger along the entire Hindu-Kush, Karakorum and Himalayan mountain ranges. In these regions, BC in snow induces an increase of the net short-wave radiation at the surface with an annual mean of 1 to 3 W m−2 leading to a localised warming between 0.05 and 0.3 °C.

scholarly journals Snow cover sensitivity to black carbon deposition in the Himalaya: from atmospheric and ice core measurements to regional climate simulations

2013 ◽  
Vol 13 (11) ◽  
pp. 31013-31040
Author(s):  
M. Ménégoz ◽  
G. Krinner ◽  
Y. Balkanski ◽  
O. Boucher ◽  
A. Cozic ◽  
...  
Keyword(s):  
Snow Cover ◽  
Black Carbon ◽  
Regional Climate ◽  
Ice Core ◽  
Shortwave Radiation ◽  
Monsoon Period ◽  
Climate Simulations ◽  
Snow Cover Duration ◽  
The Impact ◽  
Annual Duration

Abstract. We applied a climate-chemistry model to evaluate the impact of black carbon (BC) deposition on the Himalayan snow cover from 1998 to 2008. Using a stretched grid with a resolution of 50 km over this complex topography, the model reproduces reasonably well the observations of both the snow cover duration and the seasonal cycle of the atmospheric BC concentration including a maximum in atmospheric BC during the pre-monsoon period. Comparing the simulated BC concentrations in the snow with observations is challenging because of the high spatial variability and the complex vertical distribution of BC in the snow. We estimate that both wet and dry BC depositions affect the Himalayan snow cover reducing its annual duration by one to eight days. The resulting increase of the net shortwave radiation at the surface reaches an annual mean of 1 to 3 W m−2, leading to a localised warming of 0.05 to 0.3 °C.

scholarly journals Supplementary material to "Black carbon and mineral dust in snow cover on the Third Pole"

2017 ◽  
Author(s):  
Yulan Zhang ◽  
Shichang Kang ◽  
Michael Sprenger ◽  
Zhiyuan Cong ◽  
Tanguang Gao ◽  
...  
Keyword(s):  
Snow Cover ◽  
Black Carbon ◽  
Mineral Dust ◽  
The Third ◽  
Supplementary Material

scholarly journals The impact of Saharan dust and black carbon on albedo and long-term glacier mass balance

2015 ◽  
Vol 9 (1) ◽  
pp. 1133-1175 ◽  
Author(s):  
J. Gabbi ◽  
M. Huss ◽  
A. Bauder ◽  
F. Cao ◽  
M. Schwikowski
Keyword(s):  
Mass Balance ◽  
Black Carbon ◽  
Mineral Dust ◽  
Ice Cores ◽  
Swiss Alps ◽  
Saharan Dust ◽  
Glacier Mass Balance ◽  
Mass Balances ◽  
The Impact

Abstract. Light-absorbing impurities in snow and ice control glacier melt as shortwave radiation represents the main component of the surface energy balance. Here, we investigate the long-term effect of snow impurities, i.e. Saharan dust and black carbon (BC), on albedo and glacier mass balance. The analysis was performed over the period 1914–2014 for two sites on Claridenfirn, Swiss Alps, where an outstanding 100 year record of seasonal mass balance measurements is available. Information on atmospheric deposition of mineral dust and BC over the last century was retrieved from two firn/ice cores of high-alpine sites. A combined mass balance and snow/firn layer model was employed to assess the dust/BC-albedo feedback. Compared to pure snow conditions, the presence of Saharan dust and BC lowered the mean annual albedo by 0.04–0.06 and increased melt by 15–19% on average depending on the location on the glacier. BC clearly dominated absorption which is about three times higher than that of mineral dust. The upper site has experienced mainly positive mass balances and impurity layers were continuously buried whereas at the lower site, surface albedo was more strongly influenced by re-exposure of dust-enriched layers due to frequent years with negative mass balances.

Black carbon and mineral dust in snow cover across a typical city of Northeast China

2022 ◽  
Vol 807 ◽  
pp. 150397
Author(s):  
Fan Zhang ◽  
Lijuan Zhang ◽  
Mingxi Pan ◽  
Xinyue Zhong ◽  
Enbo Zhao ◽  
...  
Keyword(s):  
Snow Cover ◽  
Black Carbon ◽  
Northeast China ◽  
Mineral Dust

Constraining ice nuclei freezing efficiency using cloud phase observations together with climate models.

2021 ◽  
Author(s):  
Diego Villanueva
Keyword(s):  
Black Carbon ◽  
Climate Models ◽  
Climate Model ◽  
Mineral Dust ◽  
Dust Aerosol ◽  
Strong Constraint ◽  
Aerosol Model ◽  
Aerosol Cloud Interactions ◽  
Thermodynamic Phase ◽  
The Impact

&lt;p&gt;Aerosol-cloud interactions are an important source of uncertainty in current climate models. In particular, the role of mineral dust and soot particles in cloud glaciation is poorly understood. This lack of understanding leads to high uncertainty in climate predictions.&lt;/p&gt;&lt;p&gt;To estimate the global co-variability between mineral dust aerosol and cloud glaciation, we combined an aerosol model reanalysis with satellite retrievals of cloud thermodynamic phase. Our results confirmed that the cloud thermodynamic phase increases with higher mineral dust concentrations.&lt;/p&gt;&lt;p&gt;To better understand and quantify the impact of ice-nucleating particles on cloud glaciation, it is crucial to have a reliable estimation of the hemispheric and seasonal contrast in cloud top phase, which is believed to result from the higher dust aerosol loading in boreal spring. For this reason, we locate and quantify these contrasts by combining three different A-Train cloud-phase products for the period 2007-2010. These products rely on a spaceborne lidar, a lidar-radar synergy, and a radiometer-polarimeter synergy. We used these observations to constrain the droplet freezing in the ECHAM-HAM climate model. After tuning, the model leads to more realistic cloud-top-phase contrasts and a dust-driven glaciation effect of 0.14 &amp;#177; 0.13 Wm&amp;#8722;2 between 30&amp;#8211;60&amp;#176;N. Our results show that using observations of cloud-top phase contrasts provide a strong constraint for ice formation in mixed-phase clouds and a weak constraint for the associated impact on radiation and precipitation.&lt;/p&gt;&lt;p&gt;Besides mineral dust, it has been under debate whether black carbon also contributes to cloud glaciation. Therefore, we studied the cloud top phase retrieved by CALIOP during the Australian wildfires in 2020. After repeating the tuning strategy for black carbon, we were able to replicate the increase in ice cloud frequency observed during the wildfires.&lt;/p&gt;

scholarly journals Growth response of temperate mountain grasslands to inter-annual variations in snow cover duration

2015 ◽  
Vol 12 (12) ◽  
pp. 3885-3897 ◽  
Author(s):  
P. Choler
Keyword(s):  
Snow Cover ◽  
Primary Productivity ◽  
Growth Response ◽  
Regional Scale ◽  
Initial Growth ◽  
Annual Variations ◽  
Standing Biomass ◽  
Mountain Grasslands ◽  
Snow Cover Duration ◽  
The Impact

Abstract. A remote sensing approach is used to examine the direct and indirect effects of snow cover duration and weather conditions on the growth response of mountain grasslands located above the tree line in the French Alps. Time-integrated Normalized Difference Vegetation Index (NDVIint), used as a surrogate for aboveground primary productivity, and snow cover duration were derived from a 13-year long time series of the Moderate-resolution Imaging Spectroradiometer (MODIS). A regional-scale meteorological forcing that accounted for topographical effects was provided by the SAFRAN–CROCUS–MEPRA model chain. A hierarchical path analysis was developed to analyze the multivariate causal relationships between forcing variables and proxies of primary productivity. Inter-annual variations in primary productivity were primarily governed by year-to-year variations in the length of the snow-free period and to a much lesser extent by temperature and precipitation during the growing season. A prolonged snow cover reduces the number and magnitude of frost events during the initial growth period but this has a negligible impact on NDVIint as compared to the strong negative effect of a delayed snow melting. The maximum NDVI slightly responded to increased summer precipitation and temperature but the impact on productivity was weak. The period spanning from peak standing biomass to the first snowfall accounted for two-thirds of NDVIint and this explained the high sensitivity of NDVIint to autumn temperature and autumn rainfall that control the timing of the first snowfall. The ability of mountain plants to maintain green tissues during the whole snow-free period along with the relatively low responsiveness of peak standing biomass to summer meteorological conditions led to the conclusion that the length of the snow-free period is the primary driver of the inter-annual variations in primary productivity of mountain grasslands.

scholarly journals Black carbon and mineral dust in snow cover on the Third Pole

2017 ◽  
Author(s):  
Yulan Zhang ◽  
Shichang Kang ◽  
Michael Sprenger ◽  
Zhiyuan Cong ◽  
Tanguang Gao ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Snow Cover ◽  
Black Carbon ◽  
Mineral Dust ◽  
Regional Climate ◽  
Climate Projections ◽  
The Tibetan Plateau ◽  
Air Masses ◽  
The Third ◽  
Regional Climate Projections

Abstract. Light-absorbing impurities (including black carbon, organic carbon, and mineral dust) deposited on snow can reduce surface albedo and contribute to the near-worldwide melting of snow cover and ice. This study found that the black carbon, organic carbon, and dust concentrations in snow cover ranged generally from 202–17 468 ng g−1, 491–13 880 ng g−1, and 22–846 µg g−1, respectively, with higher concentrations in the central to northern areas of the Third Pole region (referred to by scientists also as the Tibetan Plateau and its surrounding mountains). Footprint analyses suggested that the northern Third Pole was influenced mainly by air masses from Central Asia with some Euro-Asia influence; air masses in the central and Himalayan region originated mainly from Central and South Asia. The open burning-sourced black carbon contributions decreased from ~ 50 % in the southern Third Pole region to ~ 30 % in the northern Third Pole region. The contribution of black carbon and dust to snow albedo reduction reached approximately 37 % and 15 %, respectively. The effect of black carbon and dust reduced the average snow cover duration by 3.1 ± 0.1 days to 4.4 ± 0.2 days. Meanwhile, the black carbon and dust had an import implication for snowmelt water loss over the Third Pole region. Findings indicate that the impacts of black carbon and mineral dust need to be properly accounted for in future regional climate projections, particularly in the high-altitude cryosphere.

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 

2021 ◽  
Author(s):  
Marion Réveillet ◽  
Marie Dumont ◽  
Simon Gascoin ◽  
Matthieu Lafaysse ◽  
Pierre Nabat ◽  
...  
Keyword(s):  
Snow Cover ◽  
Regional Scale ◽  
Saharan Dust ◽  
Climate Projections ◽  
Dust Deposition ◽  
Economic Implications ◽  
French Alps ◽  
Dust Events ◽  
Long Term Impact ◽  
The Impact

&lt;p&gt;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.&lt;/p&gt;

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