Waveform Retracking Analysis of Jason-2 Altimeter Data in the Four Chinese Sea Area

Three methods including offset centre of gravity retracker(OCOG), threshold method and Brown-Hayne model are evaluated in this paper. Retracking experiments were conducted for Bohai, Yellow Sea, East China Sea, and South China Sea areas using Jason-2 20 Hz Sensor geophysical data recorder(SGDR). The results show that the iterative least square method has an accuracy of 2 cm, comparing favorably to the maximum likelihood estimator (MLE) method issued by CNES in the four sea area. A 50% threshold value yields superior performance than other values applied to the China seas area with an accuracy of 3~6 cm and bias of 4~10 cm in contrast to the MLE method. The OCOG method delivers less accurate results but this may be due to the initial value in the Brown-Hayne model. The correction quantity with respect to the normal tracking points increases when close to continents and islands, especially in the South China Sea, as the biggest correction is 1m;radar waveforms are affected when satellite tracks cross the Xisha archipelago.