Abstract
Imaging altimeter (IALT) is a new type of radar altimeter system. In contrast to the conventional nadir-looking altimeters, such as HY-2A altimeter, Jason-1/2, and TOPEX/Poseidon, IALT observes the earth surface at low incident angles (2.5°–8°), so its swath is much wider and its spatial resolution is much higher than the previous altimeters. This paper presents a wind speed inversion method for the recently launched IALT onboard Tiangong-2 space station. Since the current calibration results of IALT do not agree well with the well-known wind geophysical model function at low incidence angles, a neural network is used to retrieve the ocean surface wind speed in this study. The wind speed inversion accuracy is evaluated by comparing with the ECMWF reanalysis wind speed, buoy wind speed, and in-situ ship measurements. The results show that the retrieved wind speed bias is about −0.21 m/s, and the root-mean-square (RMS) error is about 1.85 m/s. The wind speed accuracy of IALT meets the performance requirement.
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Foundation item: The National Key Research and Development Program of China under contract No. 2016YFC1401002; the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) under contract No. GML2019ZD0302; the National Natural Science Foundation of China under contract No. 41606202.
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Zhang, Y., Bao, Q., Lin, M. et al. Wind speed inversion and in-orbit assessment of the imaging altimeter on Tiangong-2 space station. Acta Oceanol. Sin. 39, 114–120 (2020). https://doi.org/10.1007/s13131-020-1687-9
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DOI: https://doi.org/10.1007/s13131-020-1687-9