Research On Inversion Algorithm Of Sea Current Based On HY - 2 Satellite Data

Current is a relatively stable aperiodic seawater mass flow with different density, due to thermal radiation, evaporation, precipitation, cold water, formed by wind stress, coriolis force and tidal forces. It is one of the common movement forms of the seawater, and maintains its various world ocean hydrological and chemical elements in relatively stable states for a long time. The sea surface velocity can be obtained directly from shipboard current meters and buoys or retrieved from satellite remote sensing technique. Due to its ability of providing long-term and wide coverage data, satellite remote sensing technique has been continuously employed to study the characteristics of sea current on a global scale. As the first dynamic enviromental satellite of China, HY-2 satellite can be employed in all weather and all day conditions to monitor the enviromental parameters such as sea surface wind field, sea surface height field, wave field, marine gravity field, ocean circulation and sea surface temperature and other important ocean parameters. The sensors onboard HY-2 satellite include radar altimeter, microwave scatterometer as well as scanning microwave radiometer, which can provide remote sensing data sources for sea current retrievals. Consequently, it is of great significance to realize the retrievals of sea current based on HY-2 satellite. The study mainly includes:1.The original data which are necessary for sea surface current retrieval are preprocessed. Sea surface height field of 1°×1° can be reliably obtained from original satellite altimeter data through certain data filtering conditions and then the corresponding grid are generated via the distance weighting method. The surface wind field of 1°×1° can be obtained by interpolating scatterometer data from HY-2 satellite. And sea surface temperature field can be obtained by AMSR-2 satellite data.2. By utilizing the empirical model algorithm and dynamic model algorithm respectively, the sea current products are produced based on HY-2 satellite. The key idea of the former algorithm is that the geostrophic current and Ekman current are considered in the calculation of sea surface velocity, whereas the key idea of the latter algorithm is that not only the sea surface height and the sea surface wind but also considering the sea surface temperature gradient field, which used the method of the orthogonal polynomial fitting at the equator.3. The retrieval results of sea current based on HY-2 satellite by using the empirical model algorithm and dynamic model algorithm are compared respectively with the corresponding results of OSCAR. The results show that the two algorithm results near the equator are better than the results in the high latitude areas. The standard deviations of the two algorithms are 0.30m/s near the equator and are 0.05m/s to 0. 10m/s in mid high latitudes. The standard deviation of the empirical model algorithm’s results has a greater value than the standard deviation of the dynamic model algorithm’s results.