Wind Field Retrieval with Rain Correction from Dual-Polarized Sentinel-1 SAR Imagery Collected during Tropical Cyclones
The purpose of this study is to include rain effects in wind field retrieval from C-band synthetic aperture radar (SAR) imagery collected under tropical cyclone conditions. An effective and operationally attractive approach to detect rain cells in SAR imagery is proposed and verified using four Sent...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-10-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/14/19/5006 |
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| author | Weizeng Shao Zhengzhong Lai Ferdinando Nunziata Andrea Buono Xingwei Jiang Juncheng Zuo |
| author_facet | Weizeng Shao Zhengzhong Lai Ferdinando Nunziata Andrea Buono Xingwei Jiang Juncheng Zuo |
| author_sort | Weizeng Shao |
| collection | DOAJ |
| description | The purpose of this study is to include rain effects in wind field retrieval from C-band synthetic aperture radar (SAR) imagery collected under tropical cyclone conditions. An effective and operationally attractive approach to detect rain cells in SAR imagery is proposed and verified using four Sentinel-1 (S-1) SAR images collected in dual-polarized (vertical-vertical (VV) and vertical-horizontal (VH)) interferometric-wide swath imaging mode during the Satellite Hurricane Observation Campaign. SAR images were collocated with ancillary observations that include sea surface wind and rain rate from the Stepped-Frequency Microwave Radiometer (SFMR) on board of the National Oceanic and Atmospheric Administration aircraft. The winds are inverted from VV- and VH-polarized S-1 image using the CMOD5.N and S1IW.NR geophysical model functions (GMFs), respectively. Location and radius of cyclone’s eye, together with the TC central pressure, are calculated from the VV-polarized SAR-derived wind and a parametric model. A cost function is proposed that consists of the difference between the measured VV-polarized SAR normalized radar cross section (NRCS) and the NRCS predicted using CMOD5.N forced with the wind speed retrieved by the VH-polarized SAR images using S1IW.NR GMF and the wind direction retrieved from the patterns visible in the SAR image. This cost function is related to the SFMR rain rate. Experimental results show that the difference between measured and predicted NRCS values range from 0.5 dB to 5 dB within a distance of 100 km from the cyclone’s eye, while the difference increases spanning from 3 dB to 6 dB for distances larger than 100 km. Following this rationale, first the rain bands are extracted from SAR imagery and, then, the composite wind fields are reconstructed by replacing: (1) dual-polarized SAR-derived winds over the rain-free regions; (2) winds simulated using the radial-vortex model over the rain-affected regions. The validation of the composite wind speed against SFMR winds yields a <2 m s<sup>−1</sup> and >0.7 correlation (COR) at all flow directions up to retrieval speeds of 70 m s<sup>−1</sup>. This result outperforms the winds estimated using the VH-polarized S1IW.NR GMF, which call for high error accuracy, such as about 4 m s<sup>−1</sup> with a 0.45 COR ranged from 330° to 360°. |
| first_indexed | 2024-03-09T21:13:31Z |
| format | Article |
| id | doaj.art-ebb8effa63a6482da30c660db0f60071 |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-09T21:13:31Z |
| publishDate | 2022-10-01 |
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| spelling | doaj.art-ebb8effa63a6482da30c660db0f600712023-11-23T21:42:19ZengMDPI AGRemote Sensing2072-42922022-10-011419500610.3390/rs14195006Wind Field Retrieval with Rain Correction from Dual-Polarized Sentinel-1 SAR Imagery Collected during Tropical CyclonesWeizeng Shao0Zhengzhong Lai1Ferdinando Nunziata2Andrea Buono3Xingwei Jiang4Juncheng Zuo5College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, ChinaCollege of Marine Sciences, Shanghai Ocean University, Shanghai 201306, ChinaDipartimento di Ingegneria, Università degli Studi di Napoli Parthenope, 80143 Napoli, ItalyDipartimento di Ingegneria, Università degli Studi di Napoli Parthenope, 80143 Napoli, ItalySouthern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, ChinaCollege of Marine Sciences, Shanghai Ocean University, Shanghai 201306, ChinaThe purpose of this study is to include rain effects in wind field retrieval from C-band synthetic aperture radar (SAR) imagery collected under tropical cyclone conditions. An effective and operationally attractive approach to detect rain cells in SAR imagery is proposed and verified using four Sentinel-1 (S-1) SAR images collected in dual-polarized (vertical-vertical (VV) and vertical-horizontal (VH)) interferometric-wide swath imaging mode during the Satellite Hurricane Observation Campaign. SAR images were collocated with ancillary observations that include sea surface wind and rain rate from the Stepped-Frequency Microwave Radiometer (SFMR) on board of the National Oceanic and Atmospheric Administration aircraft. The winds are inverted from VV- and VH-polarized S-1 image using the CMOD5.N and S1IW.NR geophysical model functions (GMFs), respectively. Location and radius of cyclone’s eye, together with the TC central pressure, are calculated from the VV-polarized SAR-derived wind and a parametric model. A cost function is proposed that consists of the difference between the measured VV-polarized SAR normalized radar cross section (NRCS) and the NRCS predicted using CMOD5.N forced with the wind speed retrieved by the VH-polarized SAR images using S1IW.NR GMF and the wind direction retrieved from the patterns visible in the SAR image. This cost function is related to the SFMR rain rate. Experimental results show that the difference between measured and predicted NRCS values range from 0.5 dB to 5 dB within a distance of 100 km from the cyclone’s eye, while the difference increases spanning from 3 dB to 6 dB for distances larger than 100 km. Following this rationale, first the rain bands are extracted from SAR imagery and, then, the composite wind fields are reconstructed by replacing: (1) dual-polarized SAR-derived winds over the rain-free regions; (2) winds simulated using the radial-vortex model over the rain-affected regions. The validation of the composite wind speed against SFMR winds yields a <2 m s<sup>−1</sup> and >0.7 correlation (COR) at all flow directions up to retrieval speeds of 70 m s<sup>−1</sup>. This result outperforms the winds estimated using the VH-polarized S1IW.NR GMF, which call for high error accuracy, such as about 4 m s<sup>−1</sup> with a 0.45 COR ranged from 330° to 360°.https://www.mdpi.com/2072-4292/14/19/5006wind retrievalrain correctiontropical cyclones |
| spellingShingle | Weizeng Shao Zhengzhong Lai Ferdinando Nunziata Andrea Buono Xingwei Jiang Juncheng Zuo Wind Field Retrieval with Rain Correction from Dual-Polarized Sentinel-1 SAR Imagery Collected during Tropical Cyclones Remote Sensing wind retrieval rain correction tropical cyclones |
| title | Wind Field Retrieval with Rain Correction from Dual-Polarized Sentinel-1 SAR Imagery Collected during Tropical Cyclones |
| title_full | Wind Field Retrieval with Rain Correction from Dual-Polarized Sentinel-1 SAR Imagery Collected during Tropical Cyclones |
| title_fullStr | Wind Field Retrieval with Rain Correction from Dual-Polarized Sentinel-1 SAR Imagery Collected during Tropical Cyclones |
| title_full_unstemmed | Wind Field Retrieval with Rain Correction from Dual-Polarized Sentinel-1 SAR Imagery Collected during Tropical Cyclones |
| title_short | Wind Field Retrieval with Rain Correction from Dual-Polarized Sentinel-1 SAR Imagery Collected during Tropical Cyclones |
| title_sort | wind field retrieval with rain correction from dual polarized sentinel 1 sar imagery collected during tropical cyclones |
| topic | wind retrieval rain correction tropical cyclones |
| url | https://www.mdpi.com/2072-4292/14/19/5006 |
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