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Evaluation of long-term changes of solar radiation in India

Soni, VK and Pandithurai, G and Pai, DS (2012) Evaluation of long-term changes of solar radiation in India. International Journal of Climatology, 32 (4). pp. 540-551.

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Abstract

Temporal and spatial variability in annually averaged global irradiance, diffuse irradiance, and bright sunshine duration over twelve stations of solar radiation network of India Meteorological Department (IMD) were evaluated for the period 1971-2005. Annually averaged all-sky global irradiance decreased between 0.1 (0.3 Wm -2) and 3.6 (9.0 Wm -2) per decade at the stations. The decrease in sunshine duration was concomitant with the decrease in global solar irradiance. The long-term trends in diffuse irradiance differed markedly between the twelve stations. Significant increasing trend in diffuse irradiance were found at the four stations under all-sky conditions, while seven stations showed increasing trend under clear sky conditions. The two most probable causes of long-term trends in radiation are changes in aerosol loading and cloud cover. Trend analyses of Angstrom's turbidity coefficient measured at three stations of IMD during the last three decades indicate that total column aerosol has increased significantly. Trend analysis of bright sunshine duration suggests long-term decrease at all the stations. Reduction in bright sunshine hours varied from 0.0 to 0.5 h per decade. There is a strong northwest-northeast gradient in sunshine duration which contributes to the spatial trends in global and diffuse solar irradiance. This paper examines the trends of global irradiance, diffuse irradiance and sunshine duration over India in all-sky conditions as well as cloud-free skies so the effect of cloud cover can be examined.

Item Type: Article
Additional Information: Copyright of this article belongs to Royal Meteorological Society.
Uncontrolled Keywords: Aerosol loading; All-sky; Bright sunshine hours; Clear sky; Cloud cover; Diffuse irradiance; Diffuse solar irradiance; Global dimming; Global irradiance; Global solar irradiances; Long-term changes; Long-term trend; Spatial trends; Sunshine; Sunshine duration; Temporal and spatial variability; Trend analysis, Atmospheric aerosols; Sun; Turbidity, Solar radiation, cloud cover; irradiance; long-term change; solar radiation; spatiotemporal analysis; trend analysis; turbidity, India
Subjects: Meteorology and Climatology
Depositing User: IITM Library
Date Deposited: 21 Dec 2013 07:16
Last Modified: 21 Dec 2013 07:16
URI: http://moeseprints.incois.gov.in/id/eprint/514

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