FN Archimer Export Format PT J TI C-Band SAR Winds for Tropical Cyclone Monitoring and Forecast in the South-West Indian Ocean BT AF Duong, Quoc-Phi Langlade, Sébastien Payan, Christophe Husson, Romain Mouche, Alexis Malardel, Sylvie AS 1:1;2:2;3:3;4:4;5:5;6:1; FF 1:;2:;3:;4:;5:PDG-ODE-LOPS-SIAM;6:; C1 Laboratoire de l’Atmosphère et des Cyclones (UMR8105 LACy), Université de La Réunion, CNRS, Météo-France, 97400 Saint-Denis, France Regional Specialized Meteorological Center for Tropical Cyclones La Réunion, Météo-France, 97400 Saint-Denis, France Centre National de Recherche Météorologique (UMR3589 CNRM), Université de Toulouse, CNRS, Météo-France, 31057 Toulouse, France Collecte Localisation Satellites (CLS), 29280 Brest, France Laboratoire d’Océanographie Physique et Spatiale, Ifremer, Université de Brest, CNRS, IRD, IUEM, 29280 Brest, France C2 UNIV LA REUNION, FRANCE METEO FRANCE, FRANCE CNRM (METEO FRANCE), FRANCE CLS, FRANCE IFREMER, FRANCE SI BREST SE PDG-ODE-LOPS-SIAM UM LOPS IN WOS Ifremer UMR DOAJ copubli-france copubli-univ-france IF 3.11 TC 6 UR https://archimer.ifremer.fr/doc/00692/80373/83490.pdf LA English DT Article DE ;SAR;3D-Var;data assimilation;tropical cyclone;sentinel;IDAI;GELENA AB 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. PY 2021 PD MAY SO Atmosphere SN 2073-4433 PU MDPI AG VL 12 IS 5 UT 000653443700001 DI 10.3390/atmos12050576 ID 80373 ER EF