Validation of Nadir SWH and Its Variance Characteristics from CFOSAT in China’s Offshore Waters
The offshore waters of China are a typical monsoon−affected area where the significant wave height (SWH) is strongly influenced by the different seasonal mean flow in winter and summer. However, limited in situ validations of the SWH have been performed on the China–France Oceanography Satellite (CF...
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| Format: | Article |
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MDPI AG
2023-02-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/15/4/1005 |
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| author | Jingwei Xu Huanping Wu Ying Xu Nikolay V. Koldunov Xiuzhi Zhang Lisha Kong Min Xu Klaus Fraedrich Xiefei Zhi |
| author_facet | Jingwei Xu Huanping Wu Ying Xu Nikolay V. Koldunov Xiuzhi Zhang Lisha Kong Min Xu Klaus Fraedrich Xiefei Zhi |
| author_sort | Jingwei Xu |
| collection | DOAJ |
| description | The offshore waters of China are a typical monsoon−affected area where the significant wave height (SWH) is strongly influenced by the different seasonal mean flow in winter and summer. However, limited in situ validations of the SWH have been performed on the China–France Oceanography Satellite (CFOSAT) in these waters. This study focused on validating CFOSAT nadir SWH data with SWH data from in situ buoy observations for China’s offshore waters and the Haiyang−2B (HY−2B) satellite, from July 2019 to December 2021. The validation against the buoy data showed that the relative absolute error has a seasonal cycle, varying in a narrow range near 35%. The RMSE of the CFOSAT nadir SWH was 0.29 m when compared against in situ observations, and CFOSAT was found to be more likely to overestimate the SWH under calm sea conditions. The sea−surface winds play a key role in calm sea conditions. The spatial distributions of the CFOSAT and HY−2B seasonal SWHs were similar, with a two−year mean SWH−field correlation coefficient of 0.98. Moreover, the coherence between the two satellites’ SWH variance increased with SWH magnitude. Our study indicates that, in such typical monsoon−influenced waters, attention should be given to the influence of sea conditions on the accuracy of CFOSAT SWH, particularly in studies that combine data from multiple, long−duration space−based sensors. |
| first_indexed | 2024-03-11T08:13:02Z |
| format | Article |
| id | doaj.art-9a1a3410bf0c4bfe9b97e7faab5c861d |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-11T08:13:02Z |
| publishDate | 2023-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-9a1a3410bf0c4bfe9b97e7faab5c861d2023-11-16T23:02:26ZengMDPI AGRemote Sensing2072-42922023-02-01154100510.3390/rs15041005Validation of Nadir SWH and Its Variance Characteristics from CFOSAT in China’s Offshore WatersJingwei Xu0Huanping Wu1Ying Xu2Nikolay V. Koldunov3Xiuzhi Zhang4Lisha Kong5Min Xu6Klaus Fraedrich7Xiefei Zhi8Key Laboratory of Meteorological Disaster, Ministry of Education (KLME)/Joint International Research Laboratory of Climate and Environment Change (ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD)/Joint Center for Data Assimilation Research and Applications, Nanjing University of Information Science and Technology (NUIST), Nanjing 210044, ChinaNational Climate Center, Beijing 100081, ChinaNational Satellite Ocean Application Service, Ministry of Natural Resources, Beijing 100081, ChinaAlfred Wegener Institute (AWI), 27568 Bremerhaven, GermanyNational Climate Center, Beijing 100081, ChinaNational Climate Center, Beijing 100081, ChinaClimate Center of Jiangsu Province, Nanjing 210008, ChinaKey Laboratory of Meteorological Disaster, Ministry of Education (KLME)/Joint International Research Laboratory of Climate and Environment Change (ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD)/Joint Center for Data Assimilation Research and Applications, Nanjing University of Information Science and Technology (NUIST), Nanjing 210044, ChinaKey Laboratory of Meteorological Disaster, Ministry of Education (KLME)/Joint International Research Laboratory of Climate and Environment Change (ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD)/Joint Center for Data Assimilation Research and Applications, Nanjing University of Information Science and Technology (NUIST), Nanjing 210044, ChinaThe offshore waters of China are a typical monsoon−affected area where the significant wave height (SWH) is strongly influenced by the different seasonal mean flow in winter and summer. However, limited in situ validations of the SWH have been performed on the China–France Oceanography Satellite (CFOSAT) in these waters. This study focused on validating CFOSAT nadir SWH data with SWH data from in situ buoy observations for China’s offshore waters and the Haiyang−2B (HY−2B) satellite, from July 2019 to December 2021. The validation against the buoy data showed that the relative absolute error has a seasonal cycle, varying in a narrow range near 35%. The RMSE of the CFOSAT nadir SWH was 0.29 m when compared against in situ observations, and CFOSAT was found to be more likely to overestimate the SWH under calm sea conditions. The sea−surface winds play a key role in calm sea conditions. The spatial distributions of the CFOSAT and HY−2B seasonal SWHs were similar, with a two−year mean SWH−field correlation coefficient of 0.98. Moreover, the coherence between the two satellites’ SWH variance increased with SWH magnitude. Our study indicates that, in such typical monsoon−influenced waters, attention should be given to the influence of sea conditions on the accuracy of CFOSAT SWH, particularly in studies that combine data from multiple, long−duration space−based sensors.https://www.mdpi.com/2072-4292/15/4/1005significant wave heightCFOSATvalidationvarianceChina’s offshore waters |
| spellingShingle | Jingwei Xu Huanping Wu Ying Xu Nikolay V. Koldunov Xiuzhi Zhang Lisha Kong Min Xu Klaus Fraedrich Xiefei Zhi Validation of Nadir SWH and Its Variance Characteristics from CFOSAT in China’s Offshore Waters Remote Sensing significant wave height CFOSAT validation variance China’s offshore waters |
| title | Validation of Nadir SWH and Its Variance Characteristics from CFOSAT in China’s Offshore Waters |
| title_full | Validation of Nadir SWH and Its Variance Characteristics from CFOSAT in China’s Offshore Waters |
| title_fullStr | Validation of Nadir SWH and Its Variance Characteristics from CFOSAT in China’s Offshore Waters |
| title_full_unstemmed | Validation of Nadir SWH and Its Variance Characteristics from CFOSAT in China’s Offshore Waters |
| title_short | Validation of Nadir SWH and Its Variance Characteristics from CFOSAT in China’s Offshore Waters |
| title_sort | validation of nadir swh and its variance characteristics from cfosat in china s offshore waters |
| topic | significant wave height CFOSAT validation variance China’s offshore waters |
| url | https://www.mdpi.com/2072-4292/15/4/1005 |
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