TROPICAL GEOGRAPHY ›› 2019, Vol. 39 ›› Issue (3): 357-364.doi: 10.13284/j.cnki.rddl.003137

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Application of Sentinel-1A Data in Offshore Wind Field Retrieval within Guangdong Province

Wu Pinghao1,2,3, Zhong Kaiwen2, Hu Hongda2, Zhao Yi1,2,3, Xu Jianhui2 and Wang Yunpeng1   

  1. (1. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; 2. Guangzhou Institute of Geography, Guangzhou 510070, China; 3. University of Chinese Academy of Sciences, Beijing 100049, China)
  • Received:2018-11-19 Revised:2019-05-01 Online:2019-05-05 Published:2019-05-05

Abstract:

Offshore wind energy resources are a common clean energy source. They have rich reserves and are widely distributed, inexpensive, and safe with few environmental constraints and large selection space. They exhibit considerable development and utilization prospects. In this paper, wind direction data were extracted based on wind stripes from Sentinel-1A data, and the CMOD5 retrieval model was used to invert the wind field in the offshore waters of Guangdong Province in March, May, July, and December 2017. Eight sites were selected, and 56 samples were compared with measured data; the sample wind speed was generally higher than measured wind speed. The mean absolute deviation (MAE) of wind speed retrieval was approximately 1.98 m/s, the root mean square error (RMAE) was approximately 2.74 m/s, and the correlation coefficient was 0.8. The wind speeds in March, May, and July were relatively close, and the MAE and RMSE were all under 2 m/s, while the average wind speed in December was above 8 m/s with a higher deviation in MAE and RMSE as the measured data did not exactly reflect satellite transit times. A comparison of the December CCMP data with the measured site data revealed a mean absolute deviation of approximately 2.96 m/s, root mean square error of approximately 4.02 m/s, and correlation coefficient of approximately 0.59. Differences were observed between the CCMP data and the measured data in December, which was similar to the retrieved wind speed data. G3358, G7427, G3704, and 59490 station errors were calculated by the four stations with the largest errors in December. The G3358 station exhibited the most significant errors: the mean absolute deviation was approximately 3.43 m/s and the root mean square error was approximately 5.01 m/s. The data period in which the G3358 station data exhibited the highest error was December 2017, and CCMP wind field data was interpolated to the study area at this period. It was found that the G3358 station is located at the wind speed stage of 12-15 m/s, which is nearest to the large wind speed area in all stations. The reason for the large deviation between the measured site data and the retrieval wind field and CCMP wind field may be related to the higher wind speed. The results of Sentinel-1A image retrieval were consistent with the measured data overall, which verifies that the COMD5 model is applicable to offshore high-resolution marine wind field data retrieval in Guangdong Province, and it provides a possibility for future research on wind energy resource and reserves estimation in Guangdong Province.

Key words: ocean wind field, Sentinel-1A, wind stripe, synthetic aperture radar, remote sensing retrieval, offshore Guangdong Province