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The proposed "Guanlan" ocean science satellite, led by China's Laoshan Laboratory, includes an interferometric radar altimeter (IRA) as a key payload. As an integral part of its development, an airborne IRA experiment was conducted on 6 November 2021, with a flight path of approximately 90 km in the South China Sea. This study investigates the IRA's ability to observe ocean sea surface height (SSH) across scales ranging from meters to mesoscale. The sea surface height anomaly (SSHA) of the IRA is aligned with the SSHA of the AVISO at scales greater than 30 km, but also demonstrates the ability to capture small-scale SSHA changes in two dimensions. We analyzed wavenumber spectra of SSHA obtained from the airborne IRA, ICESat-2, and SARAL/AltiKa satellite for this region. The results show a good agreement in power spectral density (PSD) levels between ICESat-2, SARAL/AltiKa and IRA at scales larger than 30 km. Within the submesoscale range of 1–10 km, the IRA SSHA spectrum exhibits a distinctly negative slope and the lowest energy level. The minimum PSD level of the IRA fell in the range of 10−4–10−3 m2/cycle/km, at scales around 1 km, which is more than an order of magnitude lower than that of ICESat-2, forming a spectral gap that is in agreement with the theoretical expectation. Furthermore, IRA-derived wave direction and significant wave height matched well with the MFWAM wave data. The results of this study underscore the considerable potential of airborne IRA in capturing SSHA across a range of scales, from oceanic waves to submesoscale. [ABSTRACT FROM AUTHOR]

The sea surface height (SSH) derived from radar altimetry is determined by the distance from the satellite to the sea surface and the altitude of the satellite above a reference ellipsoid. The former is measured by the radar altimeter, while the latter is determined by the precision orbit determination (POD). The clock for the POD equipment is independent from that of the radar altimeter onboard the HY-2A satellite. The time tag bias, which is the bias between the time tags provided by the two independent clocks, can greatly affect the SSH measurement accuracy of HY-2A altimeter. This paper estimates the time tag bias of HY-2A radar altimeter using the crossover differences obtained from the sensor geophysical dataset records (SGDR) from February 2014. We obtained a −0.61-ms Ku-band time tag bias and a −5.61-ms C-band time tag bias. After we added the time tag bias corrections to the SSH measurements from Ku and C bands, respectively, the means and standard deviations of the global crossover differences can be significantly reduced. We then applied the SSH measurements with the time tag biases corrected to calculate the HY-2A dual-frequency ionosphere correction, significantly improving the accuracy of the HY-2A dual-frequency ionosphere correction. [ABSTRACT FROM PUBLISHER]