Aura-MLS Observations of Water Vapor Entering the Stratosphere over the Northern Bay of Bengal and East Equatorial Indian Ocean


The space-time variations in water vapor in the upper troposphere and lower stratosphere (UTLS) over the Asian summer monsoon (ASM) regions are investigated using six years of observations from the Aura-MLS to understand the ASM role in transporting water vapor to the tropical stratosphere. While some previous studies indicated that the ASM plays a role in dehydrating the lower stratosphere, the present investigations revealed that the ASM region plays an active role in hydrating rather than dehydrating the tropical lower stratosphere. The analysis also shows that only during the month of August (ASM) is moist air pumped into the lower stratosphere over the two key geographical locations (India and Western Pacific). The air parcel from the tropical tropopause takes approximately 10 - 12 months to reach the mid-stratosphere with an ascent rate of 2.8 × 10-4 m s-1. Thus it is envisaged that the present results will have important implications in understanding the exchange processes across the tropopause and its role in stratosphere chemistry.

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