Evaluation of HY-2A Scatterometer Wind Vectors Using Data from Buoys, ERA-Interim and ASCAT during 2012–2014

Abstract

Abstract:The first Chinese operational Ku-band scatterometer on board Haiyang-2A (HY-2A), launched in August 2011, is designed for monitoring the global ocean surface wind. This study estimates the quality of the near-real-time (NRT) retrieval wind speed and wind direction from the HY-2A scatterometer for 36 months from 2012 to 2014. We employed three types of sea-surface wind data from oceanic moored buoys operated by the National Data Buoy Center (NDBC) and the Tropical Atmospheric Ocean project (TAO), the European Centre for Medium Range Weather Forecasting (ECMWF) reanalysis data (ERA-Interim), and the advanced scatterometer (ASCAT) to calculate the error statistics including mean bias, root mean square error (RMSE), and standard deviation. In addition, the rain effects on the retrieval winds were investigated using collocated Climate Prediction Center morphing method (CMORPH) precipitation data. All data were collocated with the HY-2A scatterometer wind data for comparison. The quality performances of the HY-2A NRT wind vectors data (especially the wind speeds) were satisfactory throughout the service period. The RMSEs of the HY-2A wind speeds relative to the NDBC, TAO, ERA-Interim, and ASCAT data were 1.94, 1.73, 2.25, and 1.62 m¨s´1, respectively. The corresponding RMSEs of the wind direction were 46.63˝, 43.11˝, 39.93˝, and 47.47˝, respectively. The HY-2A scatterometer overestimated low wind speeds, especially under rainy conditions. Rain exerted a diminishing effect on the wind speed retrievals with increasing wind speed, but its effect on wind direction was robust at low and moderate wind speeds. Relative to the TAO buoy data, the RMSEs without rain effect were reduced to 1.2 m¨s´1 and 39.68˝for the wind speed direction, respectively, regardless of wind speed. By investigating the objective laws between rain and the retrieval winds from HY-2A, we could improve the quality of wind retrievals through future studies.

Evaluation of HY-2A Scatterometer Ocean Surface Wind Data during 2012–2018

“…Therefore, dealing with rain contaminated data is one of the difficulties in scatterometer wind retrieval. It is especially important for scatterometer data usage under rainy conditions to study HSCAT wind field variations at different rainfall rates [20].…”

“…Xing et al (2016) also validated HSCAT wind products by using NDBC buoys, TAO, the European Centre for Medium Range Weather Forecasting (ECMWF) reanalysis data (ERA-Interim), and ASCAT data during 2012-2014. They found that rain has a significant effect on overestimating HSCAT wind speed at low and moderate wind speeds [20]. Bhaskar et al (2016) generated and evaluated two-day OSCAT wind fields with tropical Indian Ocean buoys and ASCAT data [21].…”

The Customized Automatic Processing Framework for HY-2A Satellite Marine Advanced Products

“…A few studies have been conducted on the quality assessment of HY-2A data. Xing et al [13] compared the data of HY-2A with the data of the NDBC (National Data Buoy Center) of the National Oceanic and Atmospheric Administration (NOAA), the data of the European Centre for Medium Range Weather Forecasting (ECMWF), and the data of the advanced scatterometer (ASCAT). The result shows that the quality performances of the HY-2A near-real-time wind vector data (especially the wind speeds) were satisfactory throughout the service period.…”

“…Wave Height (m) 13.58/5.25 ≤2 ≤8 0. [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] As the other microwave sensor, the scatterometer mounted on HY-2A is used to provide observations of vector wind at the sea surface.…”

“…[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] As the other microwave sensor, the scatterometer mounted on HY-2A is used to provide observations of vector wind at the sea surface. With a rotating dish antenna that can generate a pair of conically scanned pencil beams at two incidence angles, it takes multiple looks at the same sea surface area by transmitting pulses and receiving the returns either from different directions or at different polarizations.…”