Remote sensing-driven effective sky emissivity determination for atmospheric longwave radiation estimation

Effective sky emissivity is a key indicator in estimating the atmospheric downwelling longwave radiation that plays a crucial role in weather forecasting, building energy efficiency, and radiative cooling technology assessment. However, most regions lack appropriate effective sky emissivity empirical formulas since existing formulas are only locally determined. In this study, we systematically develop a remote sensing-driven method for effective sky emissivity determination and atmospheric longwave radiation estimation based on the AVHRR longwave radiation data and NASA POWER meteorological data. To validate the reliability of the method, regional ground-based measurements from Yucheng, China, were used. In addition, we further establish province-specific empirical models for effective sky emissivity across China, addressing the limited adaptability of traditional models in cross-regional applications. In summary, this study offers a novel approach to improving atmospheric radiation models using remote sensing techniques, guiding global-scale atmospheric radiation research, including radiative cooling and building energy efficiency.