Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 13 3 2009 10.5194/hess-13-319-2009 http://www.hydrol-earth-syst-sci.net/13/319/2009/ http://www.hydrol-earth-syst-sci.net/13/319/2009/hess-13-319-2009.html http://www.hydrol-earth-syst-sci.net/13/319/2009/hess-13-319-2009.pdf 319 326 2009-03-13 Topographic control of snow distribution in an alpine watershed of western Canada inferred from spatially-filtered MODIS snow products J. Tong jtong@unbc.ca S. J. Déry P. L. Jackson Natural Resources and Environmental Studies, University of Northern British Columbia, Prince George, BC, V2N 4Z9, Canada Environmental Science and Engineering Program, University of Northern British Columbia, Prince George, BC, V2N 4Z9, Canada A spatial filter (SF) is used to reduce cloud coverage in Moderate Resolution Imaging Spectroradiometer (MODIS) 8-day maximum snow cover extent products (MOD10A2) from 2000–2007, which are obtained from MODIS daily snow cover extent products (MOD10A1), to assess the topographic control on snow cover fraction (SCF) and snow cover duration (SCD) in the Quesnel River Basin (QRB) of British Columbia, Canada. Results show that the SF reduces cloud coverage and improves by 2% the accuracy of snow mapping in the QRB. The new product developed using the SF method shows larger SCF and longer SCD than MOD10A2, with higher altitudes experiencing longer snow cover and perennial snow above 2500 m. 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