Abstract:

The Pamirs, found on the western edge of the Tibetan Plateau, spans the largest high-altitude area in Central Asia. Named the Central Asian Water Tower, this mountain range is the most important water source in Central Asia, where water resources are becoming increasingly tense. To efficiently utilize its limited water resources, researchers should elucidate the temporal and spatial changes in its atmospheric precipitation. However, the understanding of temporal and spatial variations in precipitation in the Pamirs is still insufficient mainly because of the high terrain of the Pamirs and the violent terrain undulations, resulting in the extremely limited spatial representation of observational data from a single site. Such understanding is also limited because of sparse meteorological observations and complex process of accurate precipitation data collection owing to the harsh natural environment of high-altitude mountainous areas. Consequently, atmospheric precipitation and hydrological processes in the Pamirs remain unclear. In this study, a WRF model was used to simulate and understand the temporal and spatial distribution of atmospheric precipitation in the Pamirs from December 2016 to November 2017 with a high resolution of 6 km. The re-analyzed data ERA5 and Grid data CPC were examined and compared with model results to explore the distribution characteristics of falling water centers in different resolution data. WRF simulation results exhibited good spatial correlation with CPC data, and the spatial distribution of precipitation was highly consistency. WRF restored the spatial distribution of precipitation on the plateau, and its high-resolution simulation yielded more details than other data. Simulation results further revealed the blocking effect of the Pamir’s high terrain on water vapor transport, causing the seasonal precipitation of the Pamirs to be mainly concentrated on windward slopes. In winter and spring, precipitation mainly occurred on windward slopes on the west side of the Pamirs. As altitude increased, precipitation increased and remained concentrated at 3000-5000 m above sea level. Precipitation in high-altitude areas was several times that in plain areas. Summer precipitation was mainly observed in the southern foot of the Pamirs. Summer monsoon could not penetrate deep into the plateau inland because of obstruction by the plateau; thus, precipitation at the top of the plateau in summer was <100 mm.

Key words: precipitation, WRF, high elevation, Pamirs