Xinghua Zhou (First Institute of Oceanography, SOA, China)

This work presents the first calibration results for Jason-2 and SARAL/AltiKa altimetric missions using the permanent calibration facilities on the Qianli Yan islet in China. Qianli Yan islet is located at the Yellow Sea of China and only ~3km away from the crossover point of Jason-2 ascending orbit No.153 and SARAL/AltiKa ascending orbit No.735. This site is equipped with two float-type tide gauges and one continuously operating GPS station. Analysis of the Jason-2 and SARAL waveform data and geophysical data over the Qianli Yan calibration area proves that the altimeters and the microwave radiometers are not contaminated by the mainland and the islet. The accuracy of the regional geoid model, provided by the First Institute of Oceanography, State Oceanic Administration of China, and the DTU10 MSS model was accessed through the GNSS buoy experiment. Results indicate that FIO model is suitable in the Qianli Yan area for altimeter calibration. Based on those observations and the geoid model, the altimetric biases for Jason-2 and SARAL/AltiKa in 2013-2014 are determined as 2.1±0.59cm and -4.4±0.73cm, respectively. The two years’ results indicate that Jason bias has no trend. However, the SARAL/AltiKa bias presents a down trend and turns to be more stable in 2014 than 2013. The Qianli Yan results are consistent with what other international dedicated Cal/Val sites and the crossover analysis have determined.