Long-term trends of precipitable water and precipitation over the Tibetan Plateau derived from satellite and surface measurements

This study investigated the long-term trends of precipitable water and precipitation over the Tibetan Plateau using satellite and surface measurements. The results show that precipitable water in the 680-310 hPa layer of the atmosphere has increased significantly since the 1990s, with an upward trend of 6.45 cm per decade and particularly high increases in summer. However, precipitation has not shown a significantly increasing trend, and the land surface has become drier in parts of the Himalayas. The increased moisture in the atmosphere may be the result of two processes: (1) the rapid melting of glaciers and snow over the Tibetan Plateau due to enhanced regional warming and (2) a small increase in water vapor transported from low-latitude ocean sources and the Arabian Sea. Analyses of precipitation, evaporation, and the Palmer drought severity index (PDSI) indicated that the water resources on the Tibetan Plateau are decreasing and that the water storage capacity in the Himalayas may be permanently lost. (C) 2012 Elsevier Ltd. All rights reserved.