ABSTRACT
Net surface radiation defines the availability of radiative energy on and near the surface to drives many physical and physiological processes such as latent heat, sensible heat fluxes and evapotranspiration. One of the prime challenges of modelling radiation budget is estimation of net longwave radiation. Incoming longwave radiation (LWin) is one of the key components of net longwave radiation. Estimation of incoming longwave radiation in cloudy conditions has always been a challenge due to the lack of instrumentation and regular measurements at different spatial scale. In this study model for incoming longwave radiation under cloudy sky is developed using half hourly day-time incoming longwave radiation and other meteorological parameters with revised model coefficients. The developed model showed bias of -7.5 W/m2 over semi-humid climatic zone of India.
