Assessing the Climatology and Variability of High Mountain Asia Seasonal Snowpack Distribution from an 18-year Snow Reanalysis

Abstract:

Seasonal snowpack is a valuable water resource in High Mountain Asia (HMA), affecting the hydrological cycle, water availability and regional climate. Nevertheless, seasonal snow storage over the mountainous areas remains largely uncertain in this region, due to the limited observations in the complex and inaccessible terrain characteristic of HMA. To better characterize the spatial-temporal variability in seasonal snowpack over HMA, we derived and present an 18-year High Mountain Asia Snow Reanalysis (HMASR) over the joint Landsat-MODIS era (Water Years (WYs) 2000-2017). The HMASR is derived using a Bayesian reanalysis scheme, whereby fractional snow covered area (fSCA) products from Landsat and MODIS satellites are jointly used to condition prior snow estimates and generate posterior daily estimates. The dataset is provided at a resolution of 16 arc-second (~480 m) and daily, covering the major mountain ranges and the Tibetan Plateau in this region. The climatology of snow water equivalent (SWE) and snow depth over the HMA region and their interannual variability are presented in this research. To examine the impacts of seasonal snowpack on regional water availability, we also quantify the snow water storage across the major river basins (e.g. Syr Darya, Amu Darya, Indus, Ganges & Brahamputra, Yangtze, Yellow) and assess how it varies with elevation and at seasonal and interannual time scales.