Precipitation and snow cover in the Himalaya: from reanalysis to regional climate simulations

Abstract

Abstract. We applied a Regional Climate Model (RCM) to simulate precipitation and snow cover over the Himalaya, between March 2000 to December 2002. Due to its higher resolution, our model simulates a more realistic spatial variability of wind and precipitation than those of the reanalysis used as boundary conditions. In this region, we found very large discrepancies between the estimations of precipitation provided by reanalysis, rain gauges networks, satellite observations, and our RCM simulation. Our model clearly underestimates precipitation at the foothills of the Himalaya and in its Eastern part. However, our simulation brings an interesting estimation of liquid and solid precipitation in high altitude areas, where satellite and rain gauge networks are few reliable. We found our model to simulate quite accurately the snow cover extent and duration for the two years of simulation in these areas. Snow accumulation and snow duration differ widely along the Himalaya: snowfall can occur during the whole year Western Himalaya, due to both summer monsoon and mid-latitude low pressure systems bringing moisture into this region. In Central Himalaya and on the Tibetan plateau, a much more marked dry season occurs from October to March. Snow cover does not have a well marked seasonal cycle in these regions, since it depends both on the quite variable duration of the monsoon and on the rare but possible occurrence of snowfall during the winter.