Analysis of Direct, Diffuse and Global Solar Radiations over Varanasi at Eastern Indo-Gangetic Plain (IGP), India

The paper presents the seasonal solar radiations over Varanasi (25°20' N, 83° 00' E 81.1m altitude) in Eastern Uttar Pradesh (UP) in India. An investigation on solar radiation over Varanasi station, India is carried out by using the five years (2010-2014) recorded direct, diffuse, and global radiations data obtained from the radiation unit installed by India Meteorological Department (IMD) at Banaras Hindu University (BHU) campus. Analyses of winter (December, January, and February), summer (March, April, and May), monsoon season (June, July, August, September), and post monsoon (October, November) period shows that diffuse solar radiation is maximum (~1.42 MJ/m2) during monsoon season in 2012 at 12:00 IST and global solar radiation is maximum (~2.9 MJ/m2) during summer season in 2012 at 13:00 IST. The results of solar radiation are further analyzed with the aerosols optical depth over Varanasi. The increase in diffuse radiation are found to be well correlated (R= 0.67) with higher values of aerosols optical depth during summer over Varanasi.