Estimating surface solar irradiance from satellites: Past, present, and future perspectives

Surface Solar Irradiance (SSI) is a key parameter dictating surface-atmosphere interactions, driving radiative, hydrological, and land surface processes, and can thus impinge greatly upon weather and climate. It is thereby a prerequisite of many studies and applications. Estimating SSI from satellites began in the 1960s, and is currently the principal way to map SSI spatiotemporal distributions from regional to global scales. Starting from an overview of historical studies carried out in the past several decades, this paper reviews the progresses made in methodology, validation, and products over these years. First, the requirements of SSI in various studies or applications are presented along with the theoretical background of SSI satellite estimation. Methods to estimate SSI from satellites are then summarized as well as their advantages and limitations. Validations of satellite-based SSI on two typical spatial scales are discussed followed by a brief description of existing products and their accuracies. Finally, the challenges faced by current SSI satellite estimation are analyzed, and possible improvements to implement in the future are suggested. This review not only updates the review paper by Pinker et al. (1995) on satellite methods to derive SSI but also offers a more comprehensive summary of the related studies and applications.