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Multi-decadal variation of the net downward shortwave radiation over south Asia: The solar dimming effect

Kambezidis, HD and Kaskaoutis, DG and Kharol, SK and Moorthy, KK and Satheesh, SK and Kalapureddy, MCR and Badarinath, KVS and Sharma, AR and Wild, M (2012) Multi-decadal variation of the net downward shortwave radiation over south Asia: The solar dimming effect. Atmospheric Environment, 50. pp. 360-372.

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The solar radiation flux at the earth's surface has gone through decadal changes of decreasing and increasing trends over the globe. These phenomena known as dimming and brightening, respectively, have attracted the scientific interest in relation to the changes in radiative balance and climate. Despite the interest in the solar dimming/brightening phenomenon in various parts of the world, south Asia has not attracted great scientific attention so far. The present work uses the net downward shortwave radiation (NDSWR) values derived from satellites (Modern Era Retrospective-analysis for Research and Applications, MERRA 2D) in order to examine the multi-decadal variations in the incoming solar radiation over south Asia for the period of 1979-2004. From the analysis it is seen that solar dimming continues over south Asia with a trend of-0.54Wm -2yr -1. Assuming clear skies an average decrease of-0.05Wm -2yr -1 in NDSWR was observed, which is attributed to increased aerosol emissions over the region. There is evidence that the increase in cloud optical depth plays the major role for the solar dimming over the area. The cloud optical depth (MERRA retrievals) has increased by 10.7 during the study period, with the largest increase to be detected for the high-level (atmospheric pressure P<400hPa) clouds (31.2). Nevertheless, the decrease in solar radiation and the role of aerosols and clouds exhibit large monthly and seasonal variations directly affected by the local monsoon system, the anthropogenic and natural aerosol emissions. All these aspects are examined in detail aiming at shedding light into the solar dimming phenomenon over a densely populated area.

Item Type: Article
Additional Information: Copyright of this article belongs to Elsevier.
Uncontrolled Keywords: Aerosol emissions; Clear sky; Cloud optical depth; Decadal change; Earth's surface; MERRA; Monsoon system; NDSWR; Radiative balance; Research and application; Seasonal variation; Shedding light; Short-wave radiation; Solar-radiation fluxes; South Asia, Aerosols; Atmospheric pressure; Solar radiation; Sun, Atmospheric aerosols, aerosol; anthropogenic source; atmospheric pollution; brightness temperature; decadal variation; emission; optical depth; radiative transfer; satellite imagery; shortwave radiation; two-dimensional modeling, aerosol; article; atmospheric pressure; meteorological phenomena; net downward shortwave radiation; priority journal; radiation; seasonal variation; solar dimming; solar radiation; South Asia; telecommunication, South Asia
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 21 Dec 2013 07:36
Last Modified: 21 Dec 2013 07:36

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