# Present and Future Marine Microwave Satellite Missions in China
## 6 Conclusions and Prospects  
Since the 1960s, through the continuous efforts of several generations of marine remote sensing researchers, China has achieved fruitful results in marine remote sensing technology [12; 13; 16]. China has formulated a long-term plan for the development of marine satellites and has developed three series of marine satellites: Oceanic colour; oceanic dynamic environments; and oceanic monitoring. These three series will gradually form China's marine space monitoring network. Since the launch of China's first marine satellite HY-1A in 2002, China has launched four ocean-colour satellites, five marine dynamic environment satellites (including China-France Oceanography Satellite (CFOSAT)), and one marine surveillance satellite, thereby obtaining the daily observations of the global marine environment. As a result, the quality of the remote sensed products has been greatly enhanced. Satellite products play important roles in marine resource and environment monitoring processes, marine disaster prevention and mitigation processes, and maritime security management in China. With the development of marine satellites and the demand for satellite data processing, China has successfully made important breakthroughs in marine satellite remote sensing retrieval technology [87; 88]. From the aspect of marine dynamic environment satellite remote sensing technology, extraction algorithms for significant wave heights and sea surface wind fields for China's independent marine microwave (marine dynamic environment) satellite were proposed in combination with the design characteristics of China's marine microwave (marine dynamic environment) satellite, and then applied to the operational system. It was confirmed that the accuracy of the data products had successfully reached the international leading level. Considering that there is no calibration field for marine microwave (marine dynamic environment) satellites in China, a calibration method using GPS buoys and tide gauges was put forward. It was observed that for precise orbital determinations, the parameters could be estimated by a simplified dynamic method through non-differential state estimations and non-differential ambiguity fixation for the purpose of improving the accuracy of orbital determinations and positioning. In terms of marine surveillance satellite remote sensing technology, breakthroughs have been made in the traditional extractions of marine environment elements, and major progress has been achieved in marine target recognition. It is expected that through the efforts made during the next 5 to 10 years, China's marine satellite remote sensing technology will play an important role in the world [89]. First, China's marine dynamic environment satellites will gradually form a network that will provide simultaneous in-orbit operation of one polar orbit and two inclined orbit marine dynamic environmental satellites. This will meet the needs of monitoring mesoscale and subspecies scale marine dynamic phenomena, and successfully complete the world's first marine dynamic environment constellation. Second, China is vigorously carrying out research regarding new marine microwave satellite remote sensing detection technology and is expected to make important breakthroughs in the fields of wide-swath radar altimetry imaging, salinity remote sensing, and synthetic aperture radar, thereby providing key technical support for China's development of new marine satellites [90]. The accurate observations of sea surface temperatures, sea surface salinity, sea surface wind fields, sea waves, surface flow fields, and other marine dynamic environment elements will provide effective scientific data for early warnings and the forecasting of global climate changes, air-sea interactions, and catastrophic sea states. Conceptualization, M.L. and Y.J. ; methodology, Y.J. ; validation, M.L. and Y.J. ; investigation, M.L. ; resources, Y.J. ; data curation, Y.J. ; writing--original draft preparation, Y.J. ; writing--review and editing, M.L. ; funding acquisition, M.L.