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Transport of aerosols into the UTLS and their impact on the asian monsoon region as seen in a global model simulation

Fadnavis, S and Semeniuk, K and Pozzoli, L. and Schultz, MG and Ghude, SD and Das, S and Kakatkar, R (2013) Transport of aerosols into the UTLS and their impact on the asian monsoon region as seen in a global model simulation. Atmospheric Chemistry and Physics, 13 (17). pp. 8771-8786.

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Abstract

An eight-member ensemble of ECHAM5-HAMMOZ simulations for a boreal summer season is analysed to study the transport of aerosols in the upper troposphere and lower stratosphere (UTLS) during the Asian summer monsoon (ASM). The simulations show persistent maxima in black carbon, organic carbon, sulfate, and mineral dust aerosols within the anticyclone in the UTLS throughout the ASM (period from July to September), when convective activity over the Indian subcontinent is highest, indicating that boundary layer aerosol pollution is the source of this UTLS aerosol layer. The simulations identify deep convection and the associated heat-driven circulation over the southern flanks of the Himalayas as the dominant transport pathway of aerosols and water vapour into the tropical tropopause layer (TTL). Comparison of model simulations with and without aerosols indicates that anthropogenic aerosols are central to the formation of this transport pathway. Aerosols act to increase cloud ice, water vapour, and temperature in the model UTLS. Evidence of ASM transport of aerosols into the stratosphere is also found, in agreement with aerosol extinction measurements from the Halogen Occultation Experiment (HALOE) and Stratospheric Aerosol and Gas Experiment (SAGE) II. As suggested by the observations, aerosols are transported into the Southern Hemisphere around the tropical tropopause by large-scale mixing processes. Aerosol-induced circulation changes also include a weakening of the main branch of the Hadley circulation and a reduction of monsoon precipitation over India.

Item Type: Article
Additional Information: Copyrights of this article belongs to Author
Uncontrolled Keywords: aerosol; air temperature; atmospheric transport; black carbon; computer simulation; Hadley cell; monsoon; organic carbon; Southern Hemisphere; stratosphere; sulfate; summer; tropopause; troposphere; water vapor, Himalayas; India
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 19 Jun 2014 10:40
Last Modified: 19 Jun 2014 10:40
URI: http://moeseprints.incois.gov.in/id/eprint/288

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