Accuracy Assessment of HY-2A Scatterometer Wind Measurements During 2011–2017 by Comparison With Buoys, ASCAT, and ERA-Interim Data

Abstract

Chinese satellite HY-2A, carrying a Ku-band scatterometer (HSCAT), was launched in August 2011. This letter validates wind vectors retrieved by the HSCAT during October 2011–July 2017 by comparing with wind data recorded by global moored buoys, the Advanced Scatterometer (ASCAT), and ERA-Interim. HSCAT wind data are collocated with moored-buoy observations made by the National Data Buoy Center, tropical atmosphere ocean/triangle trans-ocean buoy network, pilot research moored array in the Tropical Atlantic, and research moored array for African–Asian–Australian monsoon analysis and prediction. Only buoys located offshore are selected. Their spatial and temporal differences are limited to 25 km and 30 min. The results show that the HSCAT wind speed has bias of 0.09–0.28 m/s and root-mean-square error (RMSE) of 1.24–1.52 m/s, which satisfies the mission specification of less than 2 m/s. The HSCAT wind direction has bias of 0.8°–0.9° and RMSE of 21.5°–25.8°, which is close to the mission specification of less than 20°. The HSCAT wind retrievals are overestimates at wind speeds lower than 5 m/s. The RMSEs of the HSCAT wind speed and direction decrease with increasing wind speed. Wind vectors from HSCAT and ASCAT are compared using spatial and temporal windows of 0.1° and 10 min. Results show the consistency of the wind speed; RMSEs of wind speed and direction are 1.50 m/s and 22.90°. The comparison of HSCAT and ERS-Interim wind data shows that the HSCAT provides global ocean wind data at the level required for data application.