Retrieval Of Wave Spectra With SAR And Its Characteristics Over The China Sea And Northwestern Pacific Ocean

Ocean wave is an important part of ocean dynamics, one kind of fluctuations induced bywind stress in the air-sea interaction layer. Wave forecast is significant to the numericalforecast of oceanic dynamics and constructions of navy environment. Early observationsmainly relied on the fixed buoy to obtain the time-series SWH data. With the development ofsatellite remote sensing, it provides a new technical means of measuring ocean wave. Thealtimeter is able to measure the SWH data in global coverage and climatology scale, whileSAR is capable of observing the ocean wave directional spectra, which are not comparablewith field buoy.Observations of ocean wave from the spaceborne SAR begins with the launch ofSeasat-A/SAR. Then after1990s, SAR represented by ERS-1/2-SAR and Envisat/ASARprovide a valuable tool for research and forecast of ocean wave. K.Hasselmann first proposedthe nonlinear theoretical relationship between SAR image spectrum and ocean wavedirectional spectra and presented the retrieval of directional spectra from SAR imageriesbased on the data assimilationThis study introduces the MPI retrieval method proposed by Hasselmann which is used toget directional ocean wave spectra from SAR and the software to retrieve directional oceanwave spectra based on MPI developed by Ocean Remote Sensing Institude(ORSI) of OceanUniversity of China(OUC) in detail. Then ocean wave spectras over the China Sea andNorthwest Pacific Ocean are retrieved with ASAR data collected from2003to2012.Moreover, the retrieved results are compared with buoy data provided by National Oceanicand Atmospheric Administration(NOAA), National Data Buoy Center(NDBC) and ChinaOceanic Information Network. Applicability of this algorithm is validated over the China Seaand northwestern Pacific Ocean. And errors of retrieval are determined at the same time. Thenthe yearly, seasonal and monthly mean distributions of ocean wave directional spectra overthe China Sea and Northwest Pacific Ocean are presented based on the retrieval results fromSAR data.