Snow meltwaters account for most of the yearly water budgets of many catchments in High Mountain Asia (HMA). We examine trends in snow water equivalent (SWE) using passive microwave data (1987 to 2009). We find an overall decrease in SWE in HMA, despite regions of increased SWE in the Pamir, Kunlun Shan, Eastern Himalaya, and Eastern Tien Shan. Although the average decline in annual SWE across HMA (contributing area, 2641 × 10³ km²) is low (average, -0.3%), annual SWE losses conceal distinct seasonal and spatial heterogeneities across the study region. For example, the Tien Shan has seen both strong increases in winter SWE and sharp declines in spring and summer SWE. In the majority of catchments, the most negative SWE trends are found in mid-elevation zones, which often correspond to the regions of highest snow-water storage and are somewhat distinct from glaciated areas. Negative changes in SWE storage in these mid-elevation zones have strong implications for downstream water availability.

中文翻译：

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亚洲高山地区季节性雪水当量分布的变化（1987年至2009年）。

雪融水占亚洲高山（HMA）许多集水区年度水预算的大部分。我们使用被动微波数据（1987年至2009年）研究了雪水当量（SWE）的趋势。尽管帕米尔（Pamir），昆仑山（Kunlun Shan），喜马拉雅东部（East Himalaya）和东部天山（East Tien Shan）的SWE有所增加，但我们发现HMA的SWE总体有所下降。尽管HMA（贡献区域）的年度SWE平均下降（2641×10 ³ km ²）低（平均-0.3％），年度SWE损失掩盖了整个研究区域的明显季节性和空间异质性。例如，天山冬季SWE强劲增长，而春季和夏季SWE急剧下降。在大多数流域，SWE趋势最不利的地区是海拔中部地区，该地区通常对应于雪水储存量最高的地区，并且与冰川地区有所不同。在这些中高海拔地区，SWE储量的负向变化对下游的水供应具有重大影响。