scholarly journals Case study of spatial and temporal variability of snow cover, grain size, albedo and radiative forcing in the Sierra Nevada and Rocky Mountain snowpack derived from imaging spectroscopy

2016 ◽  
Vol 10 (3) ◽  
pp. 1229-1244 ◽  
Author(s):  
Felix C. Seidel ◽  
Karl Rittger ◽  
S. McKenzie Skiles ◽  
Noah P. Molotch ◽  
Thomas H. Painter
Keyword(s):  
Grain Size ◽  
Spatial Variability ◽  
Snow Cover ◽  
Sierra Nevada ◽  
Rocky Mountains ◽  
Radiative Forcing ◽  
Infrared Imaging ◽  
Spatial And Temporal Variability ◽  
Snow Albedo ◽  
The Mean

Abstract. Quantifying the spatial distribution and temporal change in mountain snow cover, microphysical and optical properties is important to improve our understanding of the local energy balance and the related snowmelt and hydrological processes. In this paper, we analyze changes of snow cover, optical-equivalent snow grain size (radius), snow albedo and radiative forcing by light-absorbing impurities in snow and ice (LAISI) with respect to terrain elevation and aspect at multiple dates during the snowmelt period. These snow properties are derived from the NASA/JPL Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data from 2009 in California's Sierra Nevada and from 2011 in Colorado's Rocky Mountains, USA. Our results show a linearly decreasing snow cover during the ablation period in May and June in the Rocky Mountains and a snowfall-driven change in snow cover in the Sierra Nevada between February and May. At the same time, the snow grain size is increasing primarily at higher elevations and north-facing slopes from 200 microns to 800 microns on average. We find that intense snowmelt renders the mean grain size almost invariant with respect to elevation and aspect. Our results confirm the inverse relationship between snow albedo and grain size, as well as between snow albedo and radiative forcing by LAISI. At both study sites, the mean snow albedo value decreases from approximately 0.7 to 0.5 during the ablation period. The mean snow grain size increased from approximately 150 to 650 microns. The mean radiative forcing increases from 20 W m−2 up to 200 W m−2 during the ablation period. The variability of snow albedo and grain size decreases in general with the progression of the ablation period. The spatial variability of the snow albedo and grain size decreases through the melt season while the spatial variability of radiative forcing remains constant.

scholarly journals Case study of spatial and temporal variability of snow cover, grain size, albedo and radiative forcing in the Sierra Nevada and Rocky Mountain snowpack derived from imaging spectroscopy

2016 ◽  
Author(s):  
F. C. Seidel ◽  
K. Rittger ◽  
S. M. Skiles ◽  
T. H. Painter
Keyword(s):  
Grain Size ◽  
Spatial Variability ◽  
Snow Cover ◽  
Sierra Nevada ◽  
Rocky Mountains ◽  
Radiative Forcing ◽  
Infrared Imaging ◽  
Spatial And Temporal Variability ◽  
Snow Albedo ◽  
The Mean

Abstract. Quantifying the spatial distribution and temporal change in mountain snow cover, microphysical and optical properties is important to improve our understanding of the local energy balance and the related snowmelt and hydrological processes. In this paper, we analyze changes of snow cover, optical-equivalent snow grain size, snow albedo, and radiative forcing by Light Absorbing Impurities in Snow and Ice (LAISI) with respect to terrain elevation and aspect at multiple dates during the snowmelt period. These snow properties are derived from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data from 2009 of the maritime snowpack in California’s Sierra Nevada and from 2011 of the continental snowpack in Colorado’s Rocky Mountains, USA. Our results show a linearly decreasing snow cover during the ablation season in the Rocky Mountains and a snowfall driven change in snow cover in the Sierra Nevada. At the same time, the snow grain size is increasing primarily at higher elevations and north facing slopes from 200 microns to 800 microns on average. We find that intense snowmelt renders the mean grain size almost invariant with respect to elevation and aspect. Our results confirm the inverse relationship between snow albedo and grain size, as well as between snow albedo and radiative forcing by LAISI. At both study sites, the mean snow albedo value decreases from approximately 0.7 to 0.5. The mean snow grain size increased from approximately 150 to 650 microns. The mean radiative forcing increases from 20 W m−2 up to 200 W m−2 during the ablation period. The variability of snow albedo and grain size decreases in general with the progression of the ablation period. The spatial variability of the snow albedo and grain size decreases through the melt season while the spatial variability of radiative forcing remains constant.

scholarly journals Daily evolution in dust and black carbon content, snow grain size, and snow albedo during snowmelt, Rocky Mountains, Colorado

2016 ◽  
Vol 63 (237) ◽  
pp. 118-132 ◽  
Author(s):  
S. McKENZIE SKILES ◽  
THOMAS PAINTER
Keyword(s):  
Grain Size ◽  
Black Carbon ◽  
Rocky Mountains ◽  
Radiative Forcing ◽  
Negative Relationship ◽  
Snow Albedo ◽  
Wide Range ◽  
Physically Based ◽  
Minimal Mass ◽  
Log Linear

ABSTRACTLight absorbing impurities (LAI) initiate powerful snow albedo feedbacks, yet due to a scarcity of observations and measurements, LAI radiative forcing is often neglected or poorly constrained in climate and hydrological models. To support physically-based modeling of LAI processes, daily measurements of dust and black carbon (BC) stratigraphy, optical grain size, snow density and spectral albedo were collected over the 2013 ablation season in the Rocky Mountains, CO. Surface impurity concentrations exhibited a wide range of values (0.02–6.0 mg g−1 pptw) with 98% of mass being deposited by three episodic dust events in April. Even minor dust loading initiated albedo decline, and the negative relationship between dust concentrations and albedo was log-linear. As melt progressed, individual dust layers coalesced and emerged at the snow surface, with minimal mass loss to meltwater scavenging. The observations show that the convergence of dust layers at the surface reduced albedo to 0.3 and snow depth declined ~50% faster than other years with similar depth but less dust. The rapid melt led to an unexpected reduction in both grain size and density in uppermost surface layers. BC concentrations co-varied with dust concentrations but were several orders of magnitude lower (<1–20 ppb).

scholarly journals Impact of light-absorbing particles on snow albedo darkening and associated radiative forcing over High Mountain Asia: High resolution WRF-Chem modeling and new satellite observations

2018 ◽  
Author(s):  
Chandan Sarangi ◽  
Yun Qian ◽  
Karl Rittger ◽  
Kat J. Bormann ◽  
Ying Liu ◽  
...  
Keyword(s):  
Grain Size ◽  
Snow Cover ◽  
Spatial Resolution ◽  
Radiative Forcing ◽  
High Mountain ◽  
Western Himalayas ◽  
Snow Albedo ◽  
Snow Properties ◽  
Realistic Representation ◽  
The Impact

Abstract. Light-absorbing particles (LAPs), mainly dust and black carbon, can significantly impact snowmelt and regional water availability over High Mountain Asia (HMA). In this study, for the first time, online aerosol-snow interactions enabled and a fully coupled chemistry Weather Research and Forecasting (WRF-Chem) regional model is used to simulate LAP-induced radiative forcing on snow surfaces in HMA at relatively high spatial resolution (12 km, WRF-HR) than previous studies. Simulated macro- and micro-physical properties of the snowpack and LAP-induced snow darkening are evaluated against new spatially and temporally complete datasets of snow covered area, grain size, and impurities-induced albedo reduction over HMA. A WRF-Chem quasi-global simulation with the same configuration as WRF-HR but a coarser spatial resolution (1 degree, WRF-CR) is also used to illustrate the impact of spatial resolution on simulations of snow properties and aerosol distribution over HMA. Due to a more realistic representation of terrain slopes over HMA, the higher resolution model (WRF-HR) shows significantly better performance in simulating snow area cover, duration of snow cover, snow albedo and snow grain size over HMA, as well as an evidently better atmospheric aerosol loading and mean LAPs concentration in snow. However, the differences in albedo reduction from model and satellite retrievals is large during winter due to associated overestimation in simulated snow fraction. It is noteworthy that Himalayan snow cover have high magnitudes of LAP-induced snow albedo reduction (4–8 %) in summer (both from WRF-HR and satellite estimates), which, induces a snow-mediated radiative forcing of ∼ 30–50 W/m2. As a result, Himalayas (specifically western Himalayas) hold the most vulnerable glaciers and mountain snowpack to the LAP-induced snow darkening effect within HMA. In summary, coarse spatial resolution and absence of snow-aerosol interactions over Himalaya cryosphere will result in significant underestimation of aerosol effect on snow melting and regional hydroclimate.

scholarly journals Impact of light-absorbing particles on snow albedo darkening and associated radiative forcing over high-mountain Asia: high-resolution WRF-Chem modeling and new satellite observations

2019 ◽  
Vol 19 (10) ◽  
pp. 7105-7128 ◽  
Author(s):  
Chandan Sarangi ◽  
Yun Qian ◽  
Karl Rittger ◽  
Kathryn J. Bormann ◽  
Ying Liu ◽  
...  
Keyword(s):  
Grain Size ◽  
Snow Cover ◽  
Spatial Resolution ◽  
Radiative Forcing ◽  
High Mountain ◽  
Western Himalayas ◽  
Snow Albedo ◽  
Microphysical Properties ◽  
Snow Properties ◽  
The Impact

Abstract. Light-absorbing particles (LAPs), mainly dust and black carbon, can significantly impact snowmelt and regional water availability over high-mountain Asia (HMA). In this study, for the first time, online aerosol–snow interactions are enabled and a fully coupled chemistry Weather Research and Forecasting (WRF-Chem) regional model is used to simulate LAP-induced radiative forcing on snow surfaces in HMA at relatively high spatial resolution (12 km, WRF-HR) compared with previous studies. Simulated macro- and microphysical properties of the snowpack and LAP-induced snow darkening are evaluated against new spatially and temporally complete datasets of snow-covered area, grain size, and impurity-induced albedo reduction over HMA. A WRF-Chem quasi-global simulation with the same configuration as WRF-HR but a coarser spatial resolution (1∘, WRF-CR) is also used to illustrate the impact of spatial resolution on simulations of snow properties and aerosol distribution over HMA. Due to a more realistic representation of terrain slopes over HMA, the higher-resolution model (WRF-HR) shows significantly better performance in simulating snow area cover, duration of snow cover, snow albedo and snow grain size over HMA, as well as an evidently better atmospheric aerosol loading and mean LAP concentration in snow. However, the differences in albedo reduction from model and satellite retrievals is large during winter due to associated overestimation in simulated snow fraction. It is noteworthy that Himalayan snow cover has high magnitudes of LAP-induced snow albedo reduction (4 %–8 %) in pre-monsoon seasons (both from WRF-HR and satellite estimates), which induces a snow-mediated radiative forcing of ∼30–50 W m−2. As a result, the Himalayas (specifically the western Himalayas) hold the most vulnerable glaciers and mountain snowpack to the LAP-induced snow darkening effect within HMA. In summary, coarse spatial resolution and absence of snow–aerosol interactions over the Himalayan cryosphere will result in significant underestimation of aerosol effects on snow melting and regional hydroclimate.

scholarly journals Light-absorbing impurities in snow cover across Northern Xinjiang, China

2019 ◽  
Vol 65 (254) ◽  
pp. 940-956 ◽  
Author(s):  
Xinyue Zhong ◽  
Shichang Kang ◽  
Wei Zhang ◽  
Junhua Yang ◽  
Xiaofei Li ◽  
...  
Keyword(s):  
Snow Cover ◽  
Radiative Forcing ◽  
Dominant Factor ◽  
Weather Research And Forecasting ◽  
Ecological Security ◽  
Snow Albedo ◽  
Northern Xinjiang ◽  
Snow Cover Duration ◽  
Average Contribution ◽  
Semi Arid

AbstractLight-absorbing impurities (LAIs, e.g. black carbon (BC), organic carbon (OC), mineral dust (MD)) deposited on snow cover reduce albedo and accelerate its melting. Northern Xinjiang (NX) is an arid and semi-arid inland region, where snowmelt leads to frequent floods that have been a serious threat to local ecological security. There is still a lack of quantitative assessments of the effects of LAIs on snowmelt in the region. This study investigates spatial variations of LAIs in snow and its effect on snow albedo, radiative forcing (RF) and snowmelt across NX. Results showed that concentrations of BC, OC (only water-insoluble OC), MD ranged from 32 to 8841 ng g−1, 77 to 8568 ng g−1 and 0.46 to 236 µg g−1, respectively. Weather Research and Forecasting Chemistry model suggested that residential emission was the largest source of BC. Snow, Ice, and Aerosol Radiative modelling showed that the average contribution of BC and MD to snow albedo reduction was 17 and 3%, respectively. RF caused by BC significantly exceeded RF caused by MD. In different scenarios, changes in snow cover duration (SCD) caused by BC and MD decreased by 1.36 ± 0.61 to 6.12 ± 3.38 d. Compared with MD, BC was the main dominant factor in reducing snow albedo and SCD across NX.

scholarly journals Some Measurements of Settlement in a Rocky Mountains Snow Cover

1978 ◽  
Vol 20 (82) ◽  
pp. 141-148 ◽  
Author(s):  
James D. Bergen
Keyword(s):  
Grain Size ◽  
Snow Cover ◽  
Rocky Mountains ◽  
Early Spring ◽  
Fair Agreement ◽  
Snow Density ◽  
Density Measurements ◽  
Colorado Rockies ◽  
Precipitation Records ◽  
Snow Temperature

AbstractSnow-cover settlement was measured in a dry, annual sub-alpine snow cover in the Colorado Rockies with settlement gages. Settlement viscosities were calculated from the change in gage heights over various periods during the winter and early spring, and the associated overburden over the gages as estimated from density measurements and precipitation records. When adjustments are made for local snow temperature, viscosities are in fair agreement with values found in the literature from similar snow covers, although considerable scatter for a given snow density is found in all sets compared. The viscosity for a given density does not appear to vary systematically with grain size.

Intensity and spatio-temporal variability of chemical denudation in an arctic-oceanic periglacial drainage basin in northernmost Swedish Lapland

2005 ◽  
Vol 36 (1) ◽  
pp. 21-36 ◽  
Author(s):  
Achim A. Beylich
Keyword(s):  
Spatial Variability ◽  
Snow Cover ◽  
Temporal Variability ◽  
Drainage Basin ◽  
Annual Runoff ◽  
Denudation Rates ◽  
The Mean ◽  
Spatio Temporal ◽  
Alpine Environments ◽  
Arctic Summer

The intensity and spatio-temporal variability of chemical denudation was analyzed in the Latnjavagge drainage basin (9 km2; 950–1440 m a.s.l.; 68°20′N, 18°30′E), an arctic–oceanic periglacial environment in northernmost Swedish Lapland. Data on daily runoff and solute concentrations at different test sites within the selected representative drainage basin were collected during the entire arctic summer seasons of 2000, 2001, 2002 and 2003. The mean annual chemical denudation net rate for the Latnjavagge drainage basin is 5.4 t/km2 yr. Most of the annual runoff occurs when the ground is still frozen. The rate in Latnjavagge is much lower than chemical denudation rates reported for Kärkevagge (Swedish Lapland) situated close to Latnjavagge, but at a similar level to a number of other subarctic, arctic and alpine environments. Chemical denudation shows a spatio-temporal variability within the drainage basin, which is mainly caused by a spatio-temporal variability of snow cover and ground frost and a spatial variability of regolith thicknesses within Latnjavagge.

scholarly journals Radiative feedbacks of dust in snow over eastern Asia in CAM4-BAM

2018 ◽  
Vol 18 (17) ◽  
pp. 12683-12698 ◽  
Author(s):  
Xiaoning Xie ◽  
Xiaodong Liu ◽  
Huizheng Che ◽  
Xiaoxun Xie ◽  
Xinzhou Li ◽  
...  
Keyword(s):  
Snow Cover ◽  
Radiative Forcing ◽  
Source Region ◽  
Asian Dust ◽  
Significant Feature ◽  
The Tibetan Plateau ◽  
Eastern Asia ◽  
Dust Emissions ◽  
Snow Albedo ◽  
Aerosol Model

Abstract. Dust in snow on the Tibetan Plateau (TP) could reduce the visible snow albedo by changing surface optical properties and removing the snow cover through increased snowmelt, which leads to a significant positive radiative forcing and remarkably alters the regional energy balance and the eastern Asian climate system. This study extends our previous investigation in dust–radiation interactions to investigate the dust-in-snow radiative forcing (SRF) and its feedbacks on the regional climate and the dust cycle over eastern Asia through the use of the Community Atmosphere Model version 4 with a Bulk Aerosol Model parameterizations of the dust size distribution (CAM4-BAM). Our results show that SRF increases the eastern Asian dust emissions significantly by 13.7 % in the spring, countering a 7.6 % decrease in the regional emissions by the dust direct radiative forcing (DRF). SRF also remarkably affects the whole dust cycle, including transport and deposition of dust aerosols over eastern Asia. The simulations indicate an increase in dust emissions of 5.1 %, due to the combined effect of DRF and SRF. Further analysis reveals that these results are mainly due to the regional climatic feedbacks induced by SRF over eastern Asia. By reducing the snow albedo over the TP, the dust in snow mainly warms the TP and influences its thermal effects by increasing the surface sensible and latent heat flux, which in turn increases the aridity and westerly winds over northwestern China and affects the regional dust cycle. Additionally, the dust in snow also accelerates the snow-melting process, reduces the snow cover and then expands the eastern Asian dust source region, which results in increasing the regional dust emissions. Hence, a significant feature of SRF on the TP is the creation of a positive feedback loop that affects the dust cycle over eastern Asia.

scholarly journals Physically based model of the contribution of red snow algal cells to temporal changes in albedo in northwest Greenland

2020 ◽  
Vol 14 (6) ◽  
pp. 2087-2101
Author(s):  
Yukihiko Onuma ◽  
Nozomu Takeuchi ◽  
Sota Tanaka ◽  
Naoko Nagatsuka ◽  
Masashi Niwano ◽  
...  
Keyword(s):  
Grain Size ◽  
Radiative Forcing ◽  
Surface Albedo ◽  
Algal Growth ◽  
Temporal Changes ◽  
The Arctic ◽  
Snow Albedo ◽  
Snow Algae ◽  
Surface Snow ◽  
Physically Based

Abstract. Surface albedo of snow and ice is substantially reduced by inorganic impurities, such as aeolian mineral dust (MD) and black carbon (BC), and also by organic impurities, such as microbes that live in the snow. In this paper, we present the temporal changes of surface albedo, snow grain size, MD, BC and snow algal cell concentration observed on a snowpack in northwest Greenland during the ablation season of 2014 and our attempt to reproduce the changes in albedo with a physically based snow albedo model. We also attempt to reproduce the effects of inorganic impurities and the red snow algae (Sanguina nivaloides) on albedo. Concentrations of MD and red snow algae in the surface snow were found to increase in early August, while snow grain size and BC were found to not significantly change throughout the ablation season. Surface albedo was found to have decreased by 0.08 from late July to early August. The albedo simulated by the model agreed with the albedo observed during the study period. However, red snow algae exerted little effect on surface albedo in early August. This is probably owing to the abundance of smaller cells (4.9×104 cells L−1) when compared with the cell abundance of red snow reported by previous studies in the Arctic region (∼108 cells L−1). The simulation of snow albedo until the end of the melting season, with a snow algae model, revealed that the reduction in albedo attributed to red snow algae could equal 0.004, out of a total reduction of 0.102 arising from the three impurities on a snowpack in northwest Greenland. Finally, we conducted scenario simulations using the snow albedo model, coupled with the snow algae model, in order to simulate the possible effects of red snow blooming on snow albedo under warm conditions in northwest Greenland. The result suggests that albedo reduction by red snow algal growth under warm conditions (surface snow temperature of +1.5 ∘C) reached 0.04, equivalent to a radiative forcing of 7.5 W m−2 during the ablation season of 2014. This coupled albedo model has the potential to dynamically simulate snow albedo, including the effect of organic and inorganic impurities, leading to proper estimates of the surface albedo of snow cover in Greenland.

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