A study of upper troposphere and lower stratosphere water vapor above the Tibetan Plateau using AIRS and MLS data

Abstract

We use water vapor data from Atmospheric Infrared Sounder (AIRS) and Aura Microwave Limb Sounder (MLS) combined with meteorological data from ECMWF Interim (ERA-Interim) reanalysis, to study some aspects of stratosphere-troposphere exchange (STE) near the Tibetan Plateau. Apart from a distinctive region of high water vapor in the lower stratosphere (LS) in summer near the southern Tibetan Plateau (between 30°N and 35°N), the water vapor in the upper troposphere and lower stratosphere (UTLS) adjacent to the northern Tibetan Plateau (40°N-45°N) is found to be relatively higher than the surrounding regions of the same latitude in March and April. This relatively high water vapor in the northern Tibetan Plateau UTLS is proposed to be associated with approaching cold surges from the north and forced lifting of air by high orography. Another interesting feature detected in this study is the region of low water vapor values on the order of 5-7 ppmv, that is more pronounced from May to September at around 200 hPa and located at 30°N-40°N western Tibetan Plateau. This low water vapor region is found to be related to an anticyclone developed at the western Tibetan Plateau which causes sinking of dry air from the stratosphere resulting lower water vapor values in the upper troposphere. © 2011 Royal Meteorological Society.