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Observations of black carbon induced semi direct effect over Northeast India

Panicker, AS and Pandithurai, G and Safai, PD and Dipu, S and Prabha, TV and Konwar, M (2014) Observations of black carbon induced semi direct effect over Northeast India. Atmospheric Environment, 98. pp. 685-692.

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Abstract

This article reports observational evidence of Black Carbon (BC) induced cloud burning effect (Semi direct effect) for the first time over a mountainous location in North east India. Simultaneous aircraft observations of Black Carbon (BC) mass concentrations and cloud microphysical parameters were carried out over Guwahati, in Northeast India during Cloud Aerosol Interactions and Precipitation Enhancement Experiment (CAIPEEX) Phase-I in 2009. Elevated pollution layers of BC (concentration exceeding 1μgm-3) were observed over the site up to 7km on different experimental days (August 30, September 4 and 6 in 2009) in the cloud regime. The vertical heating rate and radiative forcing induced by elevated BC layers in the cloud regime were estimated using an optical model along with a radiative transfer model. The instantaneous vertical heating rate induced by BC in cloud layers is found to be as high as 2.65K/day. The instantaneous vertical heating by BC is found to be inducing a significant reduction in the measured cloud liquid water content (LWC) over the site. Subsequently, the BC stimulated heating has been found to be reducing the cloud fraction (CFR) and thus inducing a "cloud burning effect (Semi direct effect)", over the region. The estimated instantaneous BC induced radiative forcing in the cloud regime is found to be+12.7-+45.1Wm-2 during the experimental periods. This large warming and reduction in cloudiness can decrease the precipitation over the region. However, more simultaneous BC-cloud observations and further research are necessary to establish a stable "semi-direct effect" over the region.

Item Type: Article
Additional Information: Copyright of this article belongs to Elsevier.
Uncontrolled Keywords: Black carbon; Burning effects; Liquid water content; Northeast india, Heating rate, black carbon, air mass; aircraft; atmospheric pollution; black carbon; cloud microphysics; heating; radiative forcing; water content, aerosol; air pollution; aircraft; Article; atmospheric dispersion; cloud; cloud burning; cloud fraction; cloud liquid water content; combustion; controlled study; environmental parameters; heating; India; liquid; model; precipitation; radiative forcing; warming; water content, Assam; Gauhati; India
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 12 Dec 2014 05:39
Last Modified: 12 Dec 2014 05:39
URI: http://moeseprints.incois.gov.in/id/eprint/855

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