نتایج جستجو برای: snow cover

تعداد نتایج: 124383  

2013
Jeffrey R. Key Robert Mahoney Yinghui Liu Peter Romanov Mark Tschudi Igor Appel James Maslanik Dan Baldwin Xuanji Wang Paul Meade

[1] The Visible Infrared Imager Radiometer Suite (VIIRS) instrument was launched in October 2011 on the satellite now known as the Suomi National Polar-orbiting Partnership. VIIRS was designed to improve upon the capabilities of the operational Advanced Very High Resolution Radiometer and provide observation continuity with NASA’s Earth Observing System’s Moderate Resolution Imaging Spectroradi...

2008
Xingong Li Mark W. Williams

The feasibility of simulating daily snowmelt runoff in an arid mountain watershed with limited hydro-meteorological measurements was explored with an enhanced temperature-index snowmelt runoff model (SRM) in which the degree-day factor (DDF) is varied on the basis of shortwave solar radiation and snow albedo. The model satisfactorily simulated snowmelt runoff with a model efficiency of 0Ð64 for...

2008
R. C. Bales K. A. Dressler B. Imam S. R. Fassnacht D. Lampkin

[1] A cloud-masked fractional snow-covered area (SCA) product gridded at 1 km was developed from the advanced very high resolution radiometer for the Colorado River and upper Rio Grande basins for 1995–2002. Cloud cover limited SCA retrievals on any given 1-km pixel to on average once per week. There were sufficient cloud-free scenes to map SCA over at least part of the basins up to 21 days per...

Journal: :Remote Sensing 2015
Xiao-Yan Wang Jian Wang Zhi-Yong Jiang Hong-Yi Li Xiaohua Hao

The Normalized Difference Snow Index (NDSI) is an effective index for snow-cover mapping at large scales, but in forested regions the identification accuracy for snow using the NDSI is low because of forest cover effects. In this study, typical evergreen coniferous forest zones on Qilian Mountain in the Upper Heihe River Basin (UHRB) were chosen as example regions. By analyzing the spectral sig...

2001
Richard D. West

L-band and C-band microwave radar observations can help to measure the properties of snow cover on land by providing information about he soil-snow boundary condition. In this theoretical study, we xamine the sensitivities of microwave radar measurements to soil and snow characteristics, and we compare a simple model with previously published data. These data show that the thermal insulation pr...

1999
Paul D. Brooks Mark W. Williams

Here we provide an overview of current research activities on nitrogen (N) cycling in high-elevation catchments of the Colorado Front Range. We then use this information to develop a conceptual model of how snow cover controls subnivial (below snowpack) microbial processes and N leachate from the snow-soil interface to surface waters. This model is based on research that identi®es subnivial pro...

2007
DIRK VAN VUREN KENNETH B. ARMITAGE

VAN VUREN, D., and ARMITAGE, K. B. 1991. Duration of snow cover and its influence on life-history variation in yellow-bellied marmots. Can. J. Zool. 69: 1755-1758. We evaluated the relationship between growing-season phenology, as indicated by time of snow melt, and intrapopulation variation in reproduction and growth of yellow-bellied marmots. The time of snow melt explained significant propor...

Journal: :IJAGR 2012
Clayton J. Whitesides Matthew H. Connolly

The disproportionate amount of water runoff from mountains to surrounding arid and semiarid lands has generated much research in snow water equivalent (SWE) modeling. A primary input in SWE models is snow covered area (SCA) which is generally obtained via satellite imagery. Mixed pixels in alpine snow studies complicate SCA measurements and can reduce accuracy. A simple method was developed to ...

2013
Karl Rittger Thomas H. Painter Jeff Dozier

Characterization of snow is critical for understanding Earth’s water and energy cycles. Maps of snow from MODIS have seen growing use in investigations of climate, hydrology, and glaciology, but the lack of rigorous validation of different snow mapping methods compromises these studies. We examine three widely used MODIS snow products: the ‘‘binary’’ (i.e., snow yes/no) global snow maps that we...

Journal: :Remote Sensing 2017
Lin Xiao Tao Che Linling Chen Hongjie Xie Liyun Dai

Snow albedo feedback is one of the most crucial feedback processes that control equilibrium climate sensitivity, which is a central parameter for better prediction of future climate change. However, persistent large discrepancies and uncertainties are found in snow albedo feedback estimations. Remotely sensed snow cover products, atmospheric reanalysis data and radiative kernel data are used in...

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