On Deflections of Vertical Determined from HY-2A/GM Altimetry Data in the Bay of Bengal

Abstract

Satellite altimetry is an important technique to derive oceanic deflections of vertical (DOV). HaiYang-2A (HY-2A) is the first Chinese altimetry satellite launched in August 2011 to observe the global marine dynamic environment. To assess the reliability of DOVs derived from HY-2A geodetic mission data, the Bay of Bengal and its adjoining area (0°-23°N, 80°-100°E) are selected as the research area, and the accuracy of HY-2A/GM-derived DOVs is compared with that of DOVs determined from CryoSat-2-measured sea surface heights (SSHs) and SARAL/AltiKa (SARAL)-measured SSHs which are in the same period as HY-2A-measured SSHs. Compared with the along-track DOVs calculated from Sentinel-3B-measured SSHs (from cycle 20 to cycle 33), the RMS of differences for HY-2A-determined DOVs is 0.1 μrad smaller than that for SARAL-determined DOVs and CryoSat-2-determined DOVs. The differences of the along-track DOVs in the frequency domain are also analyzed by power spectral density. In addition, the XGM2019e model is adopted to evaluate the quality of the gridded DOVs model established by least-squares collocation method. Marine gravity anomaly models (SIO V30.1) and ship-borne gravity anomalies are also used to assess the accuracy of gravity anomalies derived from gridded DOVs. The whole results show that the accuracy of HY-2A-determined DOVs is coincident with that of CryoSat-2-determined DOVs and slightly lower than that of SARAL-determined DOVs. Therefore, HY-2A/GM altimetry data can be applied in establishing the global high-precision DOV model.