Spatial Scale Effect on Wind Speed Retrieval Accuracy Using Sentinel-1 Copolarization SAR

High-spatial-resolution wind fields derived from synthetic aperture radar (SAR) instruments are crucial to a wide range of applications. However, the spatial scale effect on wind speed retrieval accuracy has seldom been reported. For the purpose of understanding this issue, this letter makes a quali...

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Bibliographic Details
Published in:IEEE geoscience and remote sensing letters 2018-06, Vol.15 (6), p.882-886
Main Authors: Zhang, Kangyu, Huang, Jingfeng, Xu, Xiazhen, Guo, Qiaoying, Chen, Yaoliang, Mansaray, Lamin R., Li, Zhengquan, Wang, Xiuzhen
Format: Article
Language:English
Subjects:
Accuracy
C band
Copolarization
Geophysics
Instruments
Quality assessment
Quality control
Radar
Radar imaging
Resolution
Retrieval
Root-mean-square errors
SAR (radar)
Scale effect
Sea measurements
Sea surface
sea surface wind
Spatial discrimination
Spatial resolution
spatial scale effect
Synthetic aperture radar
synthetic aperture radar (SAR)
Wind
Wind effects
Wind fields
Wind speed
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Summary:High-spatial-resolution wind fields derived from synthetic aperture radar (SAR) instruments are crucial to a wide range of applications. However, the spatial scale effect on wind speed retrieval accuracy has seldom been reported. For the purpose of understanding this issue, this letter makes a quality assessment of wind speed retrieval accuracy based on four commonly used C-band geophysical model functions (CMOD4, CMOD-IFR2, CMOD5, and CMOD5.N) at spatial resolutions ranging from 50 m to 50 km using Sentinel-1 interferometric wide (IW) swath mode images. Our results show that the CMOD5 function is the most effective among these functions, owing to a low root-mean-square error (RMSE) of 1.17 m/s and a bias of −0.28 m/s for wind speed retrieval at a spatial resolution of 500 m. It is further observed that the variance of wind speeds retrieved from copolarized SAR images decreases exponentially with the decrease of spatial resolutions. For Sentinel-1 IW mode images, the variance of wind speeds retrieved with CMOD5 decreases rapidly from 50 to 500 m, with a drop in RMSE of 40%, and thereafter levels off. Thus, a spatial resolution of 500 m, with the CMOD5 function, is recommended optimal in this letter, for wind speed retrieval using Sentinnel-1 IW mode data.
ISSN:1545-598X
1558-0571
DOI:10.1109/LGRS.2018.2811397