Abstract
The mountains of High Mountain Asia serve as an important source of water for roughly one billion people living downstream. This research uses 15 years of dynamically downscaled precipitation produced by the Weather Research and Forecasting (WRF) model to delineate contrasts in precipitation characteristics and events between regions dominated by the Indian Summer Monsoon (ISM) versus westerly disturbances during the cool season (December to March). Cluster analysis reveals a more complex spatial pattern than indicated by some previous studies and illustrates the increasing importance of westerly disturbances at higher elevations. Although prior research suggests that a small number of westerly disturbances dominate precipitation in the western Himalaya and Karakoram, the WRF-downscaled precipitation is less dominated by infrequent large events. Integrated vapor transport (IVT) and precipitation are tightly coupled in both regions during the cool season, with precipitation maximizing for IVT from the south-southwest over the Karakoram and southeast-southwest over the western Himalaya. During the ISM, Karakoram precipitation is not strongly related to IVT direction, whereas over the western Himalaya, primary and secondary precipitation maxima occur for flow from the west-southwest and northwest, respectively. These differences in the drivers and timing of precipitation have implications for hydrology, glacier mass balance, snow accumulation, and their sensitivity to climate variability and change.
Highlights
IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
To identify regions dominated by ISM (Indian Summer Monsoon) and westerly disturbances (WDs), we applied k-means clustering to climatological monthly mean precipitation time series at each Weather Research and Forecasting (WRF) grid point, and present results for k = 6 clusters
Three clusters had an annual cycle dominated by the ISM (ISM High, Medium, and Low), two had an annual cycle dominated by WDs (WD High and Low), and one represented regions with low annual precipitation (Dry) (Figure 3a)
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The mountains of High Mountain Asia (HMA) provide essential freshwater resources for over 1 billion people living downstream [1,2]. Much of which is stored as glaciers and seasonal snowpack and released through melting, is an important contributor to the flow of the largest rivers in this region [3,4,5]. Despite the importance of precipitation in HMA as a water resource, the complex terrain of HMA, combined with the sparse distribution of weather stations and significant contribution of snow-type precipitation at upper elevations, makes precipitation characterization in this region very challenging [6,7,8,9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
