Assessment of the snow conditions in the major watersheds of Afghanistan using multispectral and passive microwave remote sensing

Since the winter season of 2004–2005, annual snow assessments have been conducted for the major watersheds of Afghanistan using multispectral (AVHRR and MODIS) and passive microwave (SSM/I and AMSR‐E) remote sensing technologies. Because of limited ground‐based observations of precipitation and snow pack conditions, remote sensing provides a unique opportunity to assess these conditions at different scales offering an appraisal of current conditions from a historical context. This paper describes the methodology that has been developed over the past seven winter seasons, wherein bi‐weekly snow products and assessments are produced including the following: current snow‐covered area (SCA) at regional and watershed scales; estimation of SCA by elevation band; current snowpack volume [snow water equivalent (SWE)] for each watershed with a historical perspective (1987–present); snow condition outlook by watershed; general summary of snow conditions based on remote sensing products and limited ground‐based observations; and if warranted, a snow melt flooding advisory. Further analysis of these snow products and assessments are presented. Moreover, comparisons between both available passive microwave estimates of SWE (SSM/I and AMSR‐E) for all watersheds differ in magnitude yet exhibit similar historical trends. The SSM/I versus AMSR‐E historical differences in SWE for each of the major Afghanistan watersheds are quantified and show a strong relationship ( R 2 = 96%) to the mean elevation of the watershed.