Calibration of HY-2A satellite significant wave heights with in situ observation
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Calibration of HY-2A satellite significant wave heights with in situ observation PENG Hailong1, 2, 3*, LIN Mingsen2, 3 1 College of Information Science and Engineering, Ocean University of China, Qingdao 266100, China 2 Nation Satellite Ocean Application Service, State Oceanic Administration, Beijing 100081, China 3 Key Laboratory of Space Ocean Remote Sensing and Application, State Oceanic Administration, Beijing 100081,
China Received 3 June 2015; accepted 20 August 2015 ©The Chinese Society of Oceanography and Springer-Verlag Berlin Heidelberg 2016
Abstract
Significant wave height (SWH) can be computed from the returning waveform of radar altimeter, this parameter is only raw estimates if it does not calibrate. But accurate calibration is important for all applications, especially for climate studies. HY-2a altimeter has been operational since April 2012 and its products are available to the scientific community. In this work, SWH data from HY-2A altimeters are calibrated against in situ buoy data from the National Data Buoy Center (NDBC), Distinguished from previous calibration studies which generally regarded buoy data as “truth”, the work of calibration for HY-2A altimeter wave data against in situ buoys was applied a more sophisticated statistical technique—the total least squares (TLS) method which can take into account errors in both variables. We present calibration results for HY-2A radar altimeter measurement of wave height against NDBC buoys. In addition, cross-calibration for HY-2A and Jason-2 wave data are talked over and the result is given. Key words: total least squares, NDBC buoys, HY-2A altimeter, significant wave height Citation: Peng Hailong, Lin Mingsen. 2016. Calibration of HY-2A satellite significant wave heights with in situ observation. Acta Oceanologica Sinica, 35(3): 79–83, doi: 10.1007/s13131-015-0758-9
1 Introduction Knowledge of ocean surface waves is critical for a safe and efficient operation of such offshore activities as transportation, fishery and oil exploration, because the energy carried by the ocean waves is considerably large and may cause significant damage to ships and fixed structures. An important parameter which characterize wave conditions is the significant wave height (SWH), defined as the crest-to-trough height of the 1/3 highest waves in the field of view (Korobkin and D’Sa, 2008). The advantage of satellite against in situ measurements is that it provides the global representation of the sea state as a map, enabling us to study large-scale dynamics of the ocean surface. The accuracy of altimeter estimates, however, must be carefully tested against the in situ data before being accepted as true sea states, particularly for climate studies, where any bias in the altimeter wave heights, even of one or two percent, would affect the statistics (Bacon and Carter, 1991). On the 15th of August, 2011, the HY-2A satellite was launched by Nation Satellite Ocean Application Service (NSOAS) of China, which carries onboard Radar altimeter, Microwave scatterometer and Microw
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