Snow cover variability in North-West Himalaya during last decade

Snow is an essential component of the cryosphere and spatio-temporal variability of snow cover over large Himalayan region is important for climate change studies, regional and global energy budget, aquatic cycles and managing water resources, etc. In the present paper, analysis of snow cover area (SCA) variation for more than a decade period from 2001 to 2016 in North-West Himalaya (NWH) and its climatic zones, i.e., lower Himalayan zone (LHZ), middle Himalayan zone (MHZ), and upper Himalayan zone (UHZ), has been presented. SCA has been estimated using 10-day maximum snow cover product derived from Moderate Resolution Imaging Spectroradiometer (MODIS) sensor images. Large inter and intra-annual variation in snow cover of NWH and its climatic zones have been observed during the data period. SCA in NWH varied from ~ 13,180 km2 (August, 2001) to ~ 2, 11,000 km2 (February, 2004) during the data period. Mean of annual and seasonal SCA has been estimated for entire NWH and its climatic zones. Mean annual SCA of NWH, LHZ, MHZ, and UHZ were estimated to be ~ 92,482 km2, ~ 8150 km2, ~ 35,078 km2, and ~ 21,190 km2 respectively. SCA was observed to be decreasing in NWH, LHZ, and MHZ at the rate of 840 km2 year−1, 31 km2 year−1, and 74 km2 year−1 respectively during 2001–2010, although the trend was statistically non-significant. Statistically significant increasing trend in SCA has been observed in UHZ at the rate of 241 km2 year−1 during 2001–2016. The paper highlights a shift in SCA trends after 2010 in NWH, LHZ, and MHZ and slowdown in snow/ice cover shrinkage during recent years. Additionally, variation in snowline elevation, snow cover duration and effect of topography on snow cover has been explored during different seasons in the NWH and its climatic zones.