Evaluation of Global Horizontal Irradiance Derived from CLAVR-x Model and COMS Imagery Over the Korean Peninsula

Satellite-derived solar irradiance was evaluated against four ground observations for clear and cloudy skies. The solar irradiance estimated by the CLAVR-x model was positively biased for clear sky and the error metrics increased when clouds exist. The COMS operational products include the solar insolation, which is underestimated when comparing with the clear sky solar irradiance measured at ground stations. The biases for clear sky were correlated with the solar zenith angle and therefore correction factor was formulated as a function of the cosine of the solar zenith angle. After the correction, the solar irradiance estimates were consistent with the observed solar irradiance. For cloudy sky, the CLAVR-x model failed to detect the cloudy pixel for shallow clouds.