Abstract:In the context of the global environment changes, highly accurate observations on the earth surface are urgently needed for the studies of the water, carbon, and energy cycles at the regional and global scales. As the rapid development of remote sensing techniques, remote sensing has achieved the capacity of monitoring many factors of the Earth land surface. Especially for the space-borne microwave remote sensing systems, they have been widely used in the quantitative monitoring of global snow, soil moisture, and vegetation parameters with their all-weather, all-time observation capabilities and their sensitivities to the characteristics of land surface factors. Accurate microwave physical models are essential for the understanding of the remote sensing observations, the development of the inversion algorithm and the improvement of the observation operator in the data assimilation systems. Based on the electromagnetic theories and microwave radiative transfer equations, researchers have achieved great successes in the microwave remote sensing fields in the recent thirty years and established theoretical scattering and emission models for a wide range of observation targets and land features, such as the single scatterers, rough surfaces, snow, and vegetation. This article systematically reviews the progresses on the microwave theoretical modelling. As the further enrichment of remote sensing datasets and the development of remote sensing theories and inversion techniques, remote sensing including microwave remote sensing will play a more important role in the studies and applications of the Earth systems.