Solar radiation estimation using sunshine hours for hot and humid climate of Konkan region

Abstract

The accurate knowledge of the solar radiation intensity at a given location is of importance to the development solar system design, crop modeling and input to other modeling purpose. In the present study an attempt was made to estimate the different components of solar radiation such Ra, Rs, Rnl, Rns, Rn using methodology suggested by FAO-56 method based on the sunshine hours and temperatures for Alibag station using 24 years weekly climatic data with 1240 observations. The correlation analysis showed that net solar radiations (Rn) showed maximum positive correlation coefficient was observed for sunshine hours followed by maximum and minimum temperature. These results indicated that the different components of solar radiation are highly influenced by sunshine hours followed by maximum temperature. This correlation analysis is helpful for development of empirical equations under limited or lack of climatic parameters. The study also found that the different component of solar radiation such as extraterrestrial radiation (Ra), clear sky solar radiation (Rso), Net shortwave solar radiation (Rns), Net long wave solar radiation (Rnl), Net solar radiation (Rn) estimated by FAO-56 method can be used for crop modeling and input to other models. The derived weekly values had revealed the more error during monsoon season which might be due to cloudy conditions and heavy rainfall. The study also developed linear regression equation Rn = 0.652*Tmean + 0.635*SSH-10.874 which can be used for prediction of solar radiation with considerable accuracy during the summer and winter season when compared with FAO-56 method.