Satellite retrieval of important ocean hydrological parameters: an overview
摘要
The ocean,which covers 71 percent of the Earth's surface,is a fundamental component of the global water cycle. Accurately monitoring the spatial and temporal dynamics of ocean hydro-physical parameters is important for comprehensive understanding of the global water cycle and the effective management of ocean water resources. Ocean remote sensing is a new and advanced space-based technique for estimating spatio-temporally distributed hydrophysical parameters. With five-decades of aerospace satellite sensors development,remote sensing approaches to retrieving ocean hydro-physical parameters appear mature. This paper briefly describes the principles of and retrieval algorithms for the main ocean hydro-physical parameters of Sea Surface Height(SSH),Sea Depth(SD),Sea Surface Current(SSC) and Water Volume Variation(WVV) using optical,passive-microwave and active-microwave remote sensing or combinations thereof. For each ocean hydro-physical parameter,the deficiencies of a single satellite sensor algorithm can be alleviated with the combined use of multi-sensors. Additionally,with the improvement of retrieval techniques,several regional and global hydro-physical parameter datasets have been generated. Hence,this paper also briefly describes the main datasets and their applications. Furthermore,to improve the retrieval accuracy of each hydro-physical parameter,the combination of observations from different sensors is a promising approach. As a result of international efforts,several new satellites are also scheduled to be launched into space,for example,the joint CNES-NASA satellite project SWOT(launch date in 2020) and China's second space lab,Tiangong-2(launch date in 2016). These satellites will greatly improve our ability to monitor the spatial and temporal dynamics of ocean hydrophysical parameters.