Temporal heterogeneity in aerosol characteristics and the resulting radiative impacts at a tropical coastal station – Part 2: Direct short wave radiative forcing

Babu, Suresh S and Moorthy, Krishna K and Satheesh, SK (2007) Temporal heterogeneity in aerosol characteristics and the resulting radiative impacts at a tropical coastal station – Part 2: Direct short wave radiative forcing. In: Annales Geophysicae, 25 (11). pp. 2309-2320.

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Abstract

Seasonal distinctiveness in the microphysical and optical properties of columnar and near-surface (in the well mixed region) aerosols, associated with changes in the prevailing synoptic conditions, were delineated based on extensive (spread over 4 years) and collocated measurements at the tropical coastal location, Trivandrum ($8.55^0 N$; $76.97^0 E$, 3m a.m.s.l.), and the results were summarized in Part 1 of this two-part paper. In Part 2, we use these properties to develop empirical seasonal aerosol models, which represent the observed features fairly accurately, separately for winter monsoon season (WMS, December through March), intermonsoon season (IMS, April and May), summer monsoon season (SMS, June through September) and post monsoon season (PMS, October and November). The models indicate a significant transformation in the aerosol environment from an anthropogenic-dominance in WMS to a naturaldominance in SMS. The modeled aerosol properties are used for estimating the direct, short wave aerosol radiative forcing, under lear-sky conditions. Our estimates show large seasonal changes. Under clear sky conditions, the daily averaged short-wave TOA forcing changes from its highest values during WMS, to the lowest values in SMS; this seasonal change being brought-in mainly by the reduction in the abundance and the mass fraction (to the composite) of black carbon aerosols and of accumulation mode aerosols. The resulting atmospheric forcing varies from the highest, (47 to $53 Wm^{-2})$ in WMS to the lowest (22 to $26 Wm^{-2})$ in SMS.

Item Type:	Journal Article
Publication:	Annales Geophysicae
Publisher:	European Geosciences Union
Additional Information:	Copyright of this article belongs to European Geosciences Union.
Keywords:	Atmospheric composition and structure (Aerosols and particles;Biosphere-atmosphere interactions;Transmission and scattering of radiation).
Department/Centre:	Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited:	11 Aug 2008
Last Modified:	19 Sep 2010 04:49
URI:	http://eprints.iisc.ac.in/id/eprint/15517

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