NDLI: An improved wind retrieval algorithm for the HY-2A scatterometer

Content Provider	Springer Nature Link
Author	Wang, Zhixiong Zhao, Chaofang Zou, Juhong Xie, Xuetong Zhang, Yi Lin, Mingsen
Copyright Year	2015
Abstract	Since January 2012, the National Satellite Ocean Application Service has released operational wind products from the HY-2A scatterometer (HY2-SCAT), using the maximum-likelihood estimation (MLE) method with a median filter. However, the quality of the winds retrieved from HY2-SCAT depends on the sub-satellite cross-track location, and poor azimuth separation in the nadir region causes particularly low-quality wind products in this region. However, an improved scheme, i.e., a multiple solution scheme (MSS) with a two-dimensional variational analysis method (2DVAR), has been proposed by the Royal Netherlands Meteorological Institute to overcome such problems. The present study used the MSS in combination with a 2DVAR technique to retrieve wind data from HY2-SCAT observations. The parameter of the empirical probability function, used to indicate the probability of each ambiguous solution being the “true” wind, was estimated based on HY2-SCAT data, and the 2DVAR method used to remove ambiguity in the wind direction. A comparison between MSS and ECMWF winds showed larger deviations at both low wind speeds (below 4 m/s) and high wind speeds (above 17 m/s), whereas the wind direction exhibited lower bias and good stability, even at high wind speeds greater than 24 m/s. The two HY2-SCAT wind data sets, retrieved by the standard MLE and the MSS procedures were compared with buoy observations. The RMS error of wind speed and direction were 1.3 m/s and 17.4°, and 1.3 m/s and 24.0° for the MSS and MLE wind data, respectively, indicating that MSS wind data had better agreement with the buoy data. Furthermore, the distributions of wind fields for a case study of typhoon Soulik were compared, which showed that MSS winds were spatially more consistent and meteorologically better balanced than MLE winds.
Starting Page	1201
Ending Page	1209
Page Count	9
File Format	PDF
ISSN	02544059
Journal	Chinese Journal of Oceanology and Limnology
Volume Number	33
Issue Number	5
e-ISSN	19935005
Language	English
Publisher	Science Press
Publisher Date	2014-11-06
Publisher Place	Heidelberg
Access Restriction	Subscribed
Subject Keyword	HY-2A scatterometer wind retrieval maximum-likelihood estimation (MLE) multiple solution scheme (MSS) two-dimensional variational analysis method (2DVAR) typhoon Soulik Oceanography
Content Type	Text
Resource Type	Article
Subject	Water Science and Technology Oceanography

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