Validation and intercomparison of HY-2A/MetOp-A/Oceansat-2 scatterometer wind products

Abstract

Sea surface winds are of great signifi cance in scientifi c research. In the last few years, three series of scatterometers were launched to measure these winds, including the Advanced Scatterometer (ASCAT) aboard Meteorological Operational Satellite A (MetOp-A) and MetOp-B, Oceansat-2 Scatterometer (OSCAT), and HY-2A Scatterometer (HY-2A SCAT). Based on buoy wind data, validation and intercomparison of these scatterometers were performed. Scatterometer-derived wind and buoy wind data were collected only if the spatial difference was less than 0.1 degree and temporal difference less than 5 min. After discarding wind direction data outside fi ve times the standard deviation, ASCAT wind products showed high accuracy in both wind speed and direction, with root-mean-square error (RMSE) 0.86 m/s and 17.97 degrees, respectively. HY-2A SCAT nearly meets the mission requirement, with RMSE for wind speed 1.23 m/s and 22.85 degrees for wind direction. OSCAT had poor performance when compared with the others. RMSE for wind speed was 1.54 m/s and 39.86 degrees for wind direction, which greatly exceeds the mission requirement of 20 degrees. In addition, the RMSE for wind direction shows a high-low pattern on buoy wind speed. However, a wind speed range from 14 to 15 m/s was found to be abnormal, and the reason remains unclear. There was no systematic dependency of both wind speed and direction residuals on buoy wind speed and cross-track location of the wind vector cells across the entire range. No seasonal variation was found for any scatterometer.

Seasonal distribution and variability of surface winds in the Indonesian seas using scatterometer and reanalysis data

“…The ASCAT operates in the C‐band, which is less sensitive to rain than Ku‐band scatterometers, such as QuikSCAT (Figa‐Saldaña et al ., 2002). The ASCAT wind product showed the highest accuracy in both wind speed and direction and have the least error statistics compared to other scatterometers data (i.e., OSCAT and HY‐2A SCAT; Wu and Chen, 2015). Kumar et al .…”

A comparison of scatterometer and HF radar wind direction measurements

“…Verhoef et al (2012) validated these winds firstly against the previous ASCAT 12.5km product which was more limited in coastal regions and secondly using a large number of collocated buoys although only one of these was south of 10 • S. They presented wind speed and wind component statistics but not wind directions. Wind direction statistics have been presented in Rani et al (2014), Wu and Chen (2015) and Bentamy et al (2008). The first two provide standard formulae for determining root mean square (rms) difference which they apply to the wind direction comparisons but they do not make it clear whether they have accounted for directions on either side of 0 • although presumably they did.…”

A More Accurate Field-to-Field Method towards the Wind Retrieval of HY-2B Scatterometer

“…There are two observation swaths, both about 500-km wide. Current ASCAT wind products are provided at two spatial resolutions over the global oceans, 12.5 km and 25 km [20]. In this article, the 12.5-km grid level 2 winds from MetOp-A ASCAT and MetOp-B ASCAT are used.…”