Cyclone Batsirai, February 2022

Altimetry over Batsirai

The figure below shows the Significant Wave Height measured by seven altimeters flying simultaneously: HaiYang-2B (CNSA/CNES), CFOSAT (CNES/CNSA), Copernicus Sentinel-3A&B (ESA/EUMETSAT), SARAL/AltiKa (ISRO/CNES), Cryosat-2 (ESA) and Jason-3 (CNES/NASA/EUMETSAT/NOAA). Among them, HaiYang-2B and Jason-3 have flown over Batsirai when it was close to Madagascar with values up to 10.8 m and 8.7 m respectively. The products used here are the along-track (level 3) Wave products disseminated by the Copernicus Marine Service (in the product named WAVE_GLO_WAV_L3_NRT_OBSERVATIONS_014_001).

Note that soon with Sentinel-6 Michael Freilich and the future Jason-3 interleaved orbit, the spatial coverage of the altimeters will be improved.

SAR wind speed measurements

Several Synthetic Aperture Radar (SAR) images were acquired with the Copernicus/ESA Sentinel-1A mission during Batsirai's lifetime.

The high-resolution map of the sea surface wind field is derived from the backscatter measurements by combining both the vertical and horizontal polarizations (VV and VH) of the SAR instrument (see plot below using the methodology described in the dedicated paper Mouche et al, 2019).

Thanks to the ESA initiative toward the spaceborne monitoring of Tropical Cyclones, the Satellite Hurricane Observation Campaign (SHOC) consists in a joint effort between the Sentinel-1 mission planning team, IFREMER and CLS. Once an alert is raised, the acquisition plan of both Sentinel-1 A and B missions is modified on short notice to capture the cyclonic event over the oceans before landfall including open ocean and coastal areas. All information on the CYMS website (CYclone MOnitoring Service).

Tropical Cyclone Heat Potential

The ocean heat content called the Tropical Cyclone Heat Potential (TCHP) is  the quantity of ocean heat available above the 26°C isotherm (minimum temperature required for cyclone generation). The figure below shows the heat pumped from the ocean by the hurricane in its wake. The TCHP is calculated from temperature data from the global ocean model PSY4V3 developed by Mercator Océan International as part of the European Copernicus Marine Service.