I. Introduction
Ocean covers more than two-thirds of the Earth and plays a crucial role in regulating the global climate. Various ocean factors, e.g., temperature, salinity, and ocean heat content, have been studied for decades to identify extreme climate events (e.g., El Niño phenomena and typhoons) and protect the ocean ecosystem [1]. With the development of sensing technology, more and more remote sensors have been deployed to monitor the changes of these ocean factors [2]. Various ocean datasets are thus collected and published by different organizations [e.g., National Aeronautics and Space Administration (NASA), European Centre for Medium-Range Weather Forecasts (ECMWF), and the Chinese Academy of Sciences (CAS)], which lays the solid foundation for analyzing the changing patterns and regularity of the ocean. For example, since 1979, NASA has launched a series of satellites [3], [4] to continually monitor the sea surface temperature (SST) and sea surface salinity (SSS) globally. Over the past decades, there have been numerous studies utilizing the collected data for predicting various ocean factors, which hold great significance for various applications, e.g., weather forecasting [5], fishing detection [6], and storm tracking [7].