Spatiotemporal distribution of seasonal snow water equivalent in High Mountain Asia from an 18-year Landsat–MODIS era snow reanalysis dataset

Abstract. Seasonal snowpack is an essential component in the hydrological cycle and plays a significant role supplying water resources to downstream users. Yet snow equivalent (SWE) seasonal snowpacks, its space–time variation, remains highly uncertain, especially over mountainous areas with complex terrain sparse observations, such as High Mountain Asia (HMA). In this work, we assessed spatiotemporal distribution of SWE, obtained from new 18-year HMA Snow Reanalysis (HMASR) dataset, part recent NASA Team (HiMAT) effort. A Bayesian reanalysis scheme previously developed assimilate satellite-derived fractional snow-covered area (fSCA) products Landsat MODIS platforms has been applied develop HMASR dataset (at spatial resolution 16 arcsec (?500 m) daily temporal resolution) joint Landsat–MODIS period covering years (WYs) 2000–2017. Based on results, HMA-wide total SWE volume found be around 163 km3 average ranges 114 (WY2001) 227 (WY2005) when 18 WYs. The most abundant snowpacks are northwestern basins (e.g., Indus, Syr Darya Amu Darya) that mainly affected by westerlies, accounting for 66 % volume. depicted accumulating through October March April, typically peaking April depleting July–October, variations across When examining elevational domain, peaks at mid-elevations (around 3500 m), 50 stored above m. Above-average amounts precipitation causes overall increase volumes all elevations, while air temperature (?1.5 K) cooler normal conditions leads redistribution storage lower elevations mid-elevations. This work brings insight into understanding climatology variability HMA, regional constrained remote-sensing data, providing reference future studies how it contributes climate region.