A long-term study of aerosol modulation of atmospheric and surface solar heating over Pune, India

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Devara, P.C.S ; Kumar, Sumit (2012)
  • Publisher: Tellus B
  • Journal: Tellus B (issn: 1600-0889)
  • Related identifiers: doi: 10.3402/tellusb.v64i0.18420
  • Subject: aerosol science | aerosol optical properties, direct radiative effect, surface albedo, Sun/Sky radiometer, heating rates

Implications of aerosol characteristics, observed during a five-year (2004–2009) period over Pune (a tropical urban location), to short-wave radiation budget are reported. A discrete ordinate radiative transfer (DISORT) model with a code, namely, Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART), has been used to carry out the radiative transfer computations. The validity of the method is demonstrated using independent ground-based remote sensing observations. Uncertainties in the estimates are also quantified. Clear-sky forcing reveals the points that include (1) Large negative bottom-of-the-atmosphere (BOA) forcing (more than−30 Wm−2) in all the months with peaks during October, December and March when the surface forcing exceeds~−40 Wm−2, and (2) Surface forcing values are higher for pre-monsoon months, while they are comparable for winter and post-monsoon months. The top-of-the-atmosphere (TOA) forcing is found to be negative during all the seasons. Large differences between TOA and BOA forcing during pre-monsoon, winter and post-monsoon indicate large absorption of radiant energy (~30 Wm−2) within the atmosphere during these seasons, thus increasing atmospheric heating by~1 K/d. These values imply that aerosols have considerable impact on the atmosphere–surface system by causing substantial warming/cooling at the atmosphere/surface. This persistent trend in strong atmospheric absorption is likely to alter atmospheric thermodynamic conditions and thus affects circulation considerably.Keywords: aerosol optical properties, direct radiative effect, surface albedo, sun/sky radiometer, heating rates(Published: 20 December 2012)Citation: Tellus B 2012, 64, 18420, http://dx.doi.org/10.3402/tellusb.v64i0.18420 
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