Validation of global irradiance derived from INSAT-3D over India

Geostationary satellites offer the possibility of producing high-frequency time series irradiance datasets, covering a large geographical area. Here, we derive half-hourly global irradiance (GHI) at 4 km spatial resolution from visible channel radiance of INSAT-3D satellite using a semi-empirical model and validate it against 19 ground stations over 2015-16, across India. Our model uses the Advanced Solis clear-sky model with monthly climatological values of modern-era retrospective analysis for research and applications-2 (MERRA-2) aerosol optical depth (AOD) and precipitable water (PW) as inputs. The relative root mean squared error (rRMSE) and relative mean bias error (rMBE) are 24.02% and -0.05%, respectively. Over the validation period, INSAT-3D derived GHI outperformed SARAH-E model and MERRA-2 reanalysis GHI.