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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2017-197
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
17 Mar 2017
Review status
This discussion paper is under review for the journal Atmospheric Chemistry and Physics (ACP).
Potential impact of carbonaceous aerosols on the Upper Troposphere and Lower Stratosphere (UTLS) during Asian summer monsoon in a global model simulation
Suvarna Fadnavis1, Gayatry Kalita1, K. Ravi Kumar1, Blaz Gasparini2, and Jui-Lin Frank Li3 1Indian Institute of Tropical Meteorology, Pune, India
2Institute for Atmospheric and Climate Science, ETH Zürich, Switzerland
3Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California
Abstract. Recent satellite observations show efficient vertical transport of Asian pollutants from the surface to the upper level anticyclone by deep monsoon convection. In this paper, we examine the transport of carbonaceous aerosols including Black Carbon (BC) and Organic Carbon (OC) into the monsoon anticyclone using of ECHAM6-HAM, a global aerosol climate model. Further, we investigate impacts of enhanced (doubled) carbonaceous aerosols emissions on the UTLS from sensitivity simulations.

These model simulations show that boundary layer aerosols are transported into the monsoon anticyclone by the strong monsoon convection from the Bay of Bengal, southern slopes of the Himalayas and the South China Sea. Doubling of emissions of BC and OC aerosols, each, over the South East Asia (10° S–50° N; 65° E–155° E) shows that lofted aerosols produce significant warming in the mid/upper troposphere. These aerosols lead to an increase in temperature by 1 K–3 K in the mid/upper troposphere and in radiative heating rates by 0.005 K/day near the tropopause. They alter aerosol radiative forcing at the surface by −1.4 W/m2; at the Top Of the Atmosphere (TOA) by +1.2 W/m2 and in the atmosphere by 2.7 W/m2 over the Asian summer monsoon region (20° N–40° N, 60° E–120° E). Atmospheric warming increases vertical velocities and thereby cloud ice in the upper troposphere. An anomalous warming over the Tibetan Plateau (TP) facilitate the relative strengthening of the monsoon Hadley circulation and elicit enhancement in precipitation over India and north east China.


Citation: Fadnavis, S., Kalita, G., Kumar, K. R., Gasparini, B., and Li, J.-L. F.: Potential impact of carbonaceous aerosols on the Upper Troposphere and Lower Stratosphere (UTLS) during Asian summer monsoon in a global model simulation, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-197, in review, 2017.
Suvarna Fadnavis et al.
Suvarna Fadnavis et al.
Suvarna Fadnavis et al.

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Short summary
In this study, the model simulations show that monsoon convection over the Bay of Bengal, the South China Sea and Southern flanks of the Himalayas transport Asian carbonaceous aerosol into the UTLS. Carbonaceous aerosol induces enhancement in heating rate, vertical velocity and water vapor transport in the UTLS.Doubling of BC + OC aerosols creates an anomalous warming over the TP. It elicits monsoon Hadley circulation and thus increases precipitation over India and northeast China.
In this study, the model simulations show that monsoon convection over the Bay of Bengal, the...
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