Low-to-Moderate Wind Speed Retrieval from Sentenel-L Dual-Polarized Sar Images

2018 ◽  
Author(s):  
Yang Chao ◽  
Dongxiang Zhang ◽  
Kaijun Ren ◽  
Jia Liu ◽  
Chaoxiong Ke
Keyword(s):  
Wind Speed ◽  
Sar Images ◽  
Dual Polarized

scholarly journals A Wind Speed Retrieval Model for Sentinel-1A EW Mode Cross-Polarization Images

2019 ◽  
Vol 11 (2) ◽  
pp. 153 ◽  
Author(s):  
Yuan Gao ◽  
Changlong Guan ◽  
Jian Sun ◽  
Lian Xie
Keyword(s):  
Wind Speed ◽  
Incidence Angle ◽  
Surface Wind ◽  
European Space Agency ◽  
Sea Surface ◽  
Cross Polarization ◽  
Retrieval Model ◽  
Sar Images ◽  
Wind Speeds ◽  
Sea Surface Wind

In contrast to co-polarization (VV or HH) synthetic aperture radar (SAR) images, cross-polarization (CP for VH or HV) SAR images can be used to retrieve sea surface wind speeds larger than 20 m/s without knowing the wind directions. In this paper, a new wind speed retrieval model is proposed for European Space Agency (ESA) Sentinel-1A (S-1A) Extra-Wide swath (EW) mode VH-polarized images. Nineteen S-1A images under tropical cyclone condition observed in the 2016 hurricane season and the matching data from the Soil Moisture Active Passive (SMAP) radiometer are collected and divided into two datasets. The relationships between normalized radar cross-section (NRCS), sea surface wind speed, wind direction and radar incidence angle are analyzed for each sub-band, and an empirical retrieval model is presented. To correct the large biases at the center and at the boundaries of each sub-band, a corrected model with an incidence angle factor is proposed. The new model is validated by comparing the wind speeds retrieved from S-1A images with the wind speeds measured by SMAP. The results suggest that the proposed model can be used to retrieve wind speeds up to 35 m/s for sub-bands 1 to 4 and 25 m/s for sub-band 5.

scholarly journals Comparison of C-Band Quad-Polarization Synthetic Aperture Radar Wind Retrieval Models

2018 ◽  
Vol 10 (9) ◽  
pp. 1448 ◽  
Author(s):  
He Fang ◽  
Tao Xie ◽  
William Perrie ◽  
Guosheng Zhang ◽  
Jingsong Yang ◽  
...  
Keyword(s):  
Wind Speed ◽  
Synthetic Aperture Radar ◽  
Surface Wind ◽  
Synthetic Aperture ◽  
Northwest Pacific ◽  
Sar Images ◽  
Retrieval Models ◽  
Wind Retrieval ◽  
Wind Speeds ◽  
Aperture Radar

This work discusses the accuracy of C-2PO (C-band cross-polarized ocean backscatter) and CMOD4 (C-band model) geophysical model functions (GMF) for sea surface wind speed retrieval from satellite-born Synthetic Aperture Radar (SAR) images over in the Northwest Pacific off the coast of China. In situ observations are used for comparison of the retrieved wind speed using two established wind retrieval models: C-2PO model and CMOD4 GMF. Using 439 samples from 92 RADARSAT-2 fine quad-polarization SAR images and corresponding reference winds, we created two subset wind speed databases: the training and testing subsets. From the training data subset, we retrieve ocean surface wind speeds (OSWSs) from different models at each polarization and compare with reference wind speeds. The RMSEs of SAR-retrieved wind speeds are: 2.5 m/s: 2.11 m/s (VH-polarized), 2.13 m/s (HV-polarized), 1.86 m/s (VV-polarized) and 2.26 m/s (HH-polarized) and the correlation coefficients are 0.86 (VH-polarized), 0.85(HV-polarized), 0.87(VV-polarized) and 0.83 (HH-polarized), which are statistically significant at the 99.9% significance level. Moreover, we found that OSWSs retrieved using C-2PO model at VH-polarized are most suitable for moderate-to-high winds while CMOD4 GMF at VV-polarized tend to be best for low-to-moderate winds. A hybrid wind retrieval model is put forward composed of the two models, C-2PO and CMOD4 and sets of SAR test data are used in order to establish an appropriate wind speed threshold, to differentiate the wind speed range appropriate for one model from that of the other. The results show that the OSWSs retrieved using our hybrid method has RMSE of 1.66 m/s and the correlation coefficient are 0.9, thereby significantly outperforming both the C-2PO and CMOD4 models.

Study on Comparison Analysis and Error Analysis of Polarization Ratio Models

2013 ◽  
Vol 655-657 ◽  
pp. 735-739
Author(s):  
Ke Wang ◽  
Yuan Zhang ◽  
Yan Bo Hui ◽  
Feng Wang ◽  
Hong Yan Li ◽  
...  
Keyword(s):  
Wind Speed ◽  
Error Analysis ◽  
Wind Field ◽  
Incidence Angle ◽  
Surface Wind ◽  
Comparison Analysis ◽  
Polarization Ratio ◽  
Sar Images ◽  
Ocean Surface Wind ◽  
Surface Wind Field

Polarization ratio models are key problem for ocean surface wind field retrieval from HH polarization SAR images. This paper studied deeply on various polarization ratio models, and carried on comparison analysis and error analysis about them. We analyzed influence of incidence angle, azimuth, and wind speed for polarization ratio. By using true measurement of polarization ratio, we statistically valuated ability of various polarization ratio models, and proposed the best choice of polarization ratio models. Our research has guide meaning for using polarization ratio models reasonably.

Validation of wind speed retrieval from RISAT-1 SAR images of the North Indian Ocean

2018 ◽  
Vol 9 (5) ◽  
pp. 421-428 ◽  
Author(s):  
Jagdish ◽  
S. V. V. Arun Kumar ◽  
Abhisek Chakraborty ◽  
Raj Kumar
Keyword(s):  
Wind Speed ◽  
Indian Ocean ◽  
North Indian Ocean ◽  
Sar Images ◽  
The North
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