C-Band SAR Winds for Tropical Cyclone Monitoring and Forecast in the South-West Indian Ocean
Tropical cyclone (TC) monitoring and forecast in the South West Indian Ocean (SWIO) basin remain challenging, notably because of the lack of direct observations. During the 2018–2019 cyclone season, S-1 Sentinel SAR images were acquired, as part of the ReNovRisk-Cyclone research program, giving acce...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-04-01
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| Series: | Atmosphere |
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| Online Access: | https://www.mdpi.com/2073-4433/12/5/576 |
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| author | Quoc-Phi Duong Sébastien Langlade Christophe Payan Romain Husson Alexis Mouche Sylvie Malardel |
| author_facet | Quoc-Phi Duong Sébastien Langlade Christophe Payan Romain Husson Alexis Mouche Sylvie Malardel |
| author_sort | Quoc-Phi Duong |
| collection | DOAJ |
| description | Tropical cyclone (TC) monitoring and forecast in the South West Indian Ocean (SWIO) basin remain challenging, notably because of the lack of direct observations. During the 2018–2019 cyclone season, S-1 Sentinel SAR images were acquired, as part of the ReNovRisk-Cyclone research program, giving access to unprecedented detailed TC wind structure description without wind speed limitation. This paper assesses the quality of these data and the impact of their assimilation for TC forecasts. SAR observations are compared with analyses from a convection-permitting, limited area model AROME OI 3D-Var and with wind products used for operational TC monitoring. Their bias depends on the angle of incidence of the radar and the observation error is larger for extreme wind speed. The impact of SAR assimilation in AROME OI 3D-Var is assessed through two case studies. In the TC GELENA case, it leads to a better TC positioning and an improved representation of inner and outer vortex structures. The TC intensity reduction in the analysis propagates through subsequent analyses and it has an impact on forecasts for around 12 h. In the TC IDAI case, the 3D-Var does not manage to reproduce TC intensity captured by SAR. In both cases, the modification of the initial conditions has little influence on the intensification rate of the model forecasts. Sensitivity tests show that these results are robust to different observation errors and thinning. |
| first_indexed | 2024-03-09T04:57:19Z |
| format | Article |
| id | doaj.art-91f5735d5c864561ba07c0f0e0c97d6f |
| institution | Directory Open Access Journal |
| issn | 2073-4433 |
| language | English |
| last_indexed | 2024-03-09T04:57:19Z |
| publishDate | 2021-04-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Atmosphere |
| spelling | doaj.art-91f5735d5c864561ba07c0f0e0c97d6f2023-12-03T13:03:59ZengMDPI AGAtmosphere2073-44332021-04-0112557610.3390/atmos12050576C-Band SAR Winds for Tropical Cyclone Monitoring and Forecast in the South-West Indian OceanQuoc-Phi Duong0Sébastien Langlade1Christophe Payan2Romain Husson3Alexis Mouche4Sylvie Malardel5Laboratoire de l’Atmosphère et des Cyclones (UMR8105 LACy), Université de La Réunion, CNRS, Météo-France, 97400 Saint-Denis, FranceRegional Specialized Meteorological Center for Tropical Cyclones La Réunion, Météo-France, 97400 Saint-Denis, FranceCentre National de Recherche Météorologique (UMR3589 CNRM), Université de Toulouse, CNRS, Météo-France, 31057 Toulouse, FranceCollecte Localisation Satellites (CLS), 29280 Brest, FranceLaboratoire d’Océanographie Physique et Spatiale, Ifremer, Université de Brest, CNRS, IRD, IUEM, 29280 Brest, FranceLaboratoire de l’Atmosphère et des Cyclones (UMR8105 LACy), Université de La Réunion, CNRS, Météo-France, 97400 Saint-Denis, FranceTropical cyclone (TC) monitoring and forecast in the South West Indian Ocean (SWIO) basin remain challenging, notably because of the lack of direct observations. During the 2018–2019 cyclone season, S-1 Sentinel SAR images were acquired, as part of the ReNovRisk-Cyclone research program, giving access to unprecedented detailed TC wind structure description without wind speed limitation. This paper assesses the quality of these data and the impact of their assimilation for TC forecasts. SAR observations are compared with analyses from a convection-permitting, limited area model AROME OI 3D-Var and with wind products used for operational TC monitoring. Their bias depends on the angle of incidence of the radar and the observation error is larger for extreme wind speed. The impact of SAR assimilation in AROME OI 3D-Var is assessed through two case studies. In the TC GELENA case, it leads to a better TC positioning and an improved representation of inner and outer vortex structures. The TC intensity reduction in the analysis propagates through subsequent analyses and it has an impact on forecasts for around 12 h. In the TC IDAI case, the 3D-Var does not manage to reproduce TC intensity captured by SAR. In both cases, the modification of the initial conditions has little influence on the intensification rate of the model forecasts. Sensitivity tests show that these results are robust to different observation errors and thinning.https://www.mdpi.com/2073-4433/12/5/576SAR3D-Vardata assimilationtropical cyclonesentinelIDAI |
| spellingShingle | Quoc-Phi Duong Sébastien Langlade Christophe Payan Romain Husson Alexis Mouche Sylvie Malardel C-Band SAR Winds for Tropical Cyclone Monitoring and Forecast in the South-West Indian Ocean Atmosphere SAR 3D-Var data assimilation tropical cyclone sentinel IDAI |
| title | C-Band SAR Winds for Tropical Cyclone Monitoring and Forecast in the South-West Indian Ocean |
| title_full | C-Band SAR Winds for Tropical Cyclone Monitoring and Forecast in the South-West Indian Ocean |
| title_fullStr | C-Band SAR Winds for Tropical Cyclone Monitoring and Forecast in the South-West Indian Ocean |
| title_full_unstemmed | C-Band SAR Winds for Tropical Cyclone Monitoring and Forecast in the South-West Indian Ocean |
| title_short | C-Band SAR Winds for Tropical Cyclone Monitoring and Forecast in the South-West Indian Ocean |
| title_sort | c band sar winds for tropical cyclone monitoring and forecast in the south west indian ocean |
| topic | SAR 3D-Var data assimilation tropical cyclone sentinel IDAI |
| url | https://www.mdpi.com/2073-4433/12/5/576 |
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