16:30 〜 16:45
[AAS02-17] SWOT: New capabilities for monitoring sea level anomalies in the wake of tropical cyclones.
キーワード：Tropical cyclone , Ocean response, SWOT, SSHA
Sea surface height anomalies (SSHA) are an integral variable of the vertical processes and air/sea interactions that occur in the water column, during the passage of an extreme event (i.e. Tropical Cyclone). Yet, this parameter has often been overlooked, as precise temporal monitoring of these anomalies is made difficult by the sole use of nadir-looking observations.
The groundbreaking Ka-band interferometric radar (KaRIn), on board the recent satellite mission SWOT, is capable of measuring the ocean surface topography at high resolution (250m/1km) over a total width of 120 km. Thanks to a 1-day repetition cycle in its initial deployment phase (until July 2023), we have seized this unique opportunity to analyse the evolution of the wake of Typhoon Mawar, with an unprecedented temporal resolution. These first results highlight the unique ability of SWOT to observe and confirm, using a single repeated-orbit track, 1) the westward deviation of the surface anomalies, that was found in agreement with previous estimates of ~0.1°/day, and 2) the persistence of these signatures over more than 40 days. In a second time, Different pre-cyclonic averages can be also easily derived to dissociate and understand the interactions between the wake of Mawar and that of Guchol, which occurs around ten days later. A barycentric approach was used to monitor and estimate the surface anomalies induced by the two storms. Finally, the use of the current recurrence cycle (21 days) results in a larger spatial sampling of the SSHAs (2023-2024 cases) and a better picture of the wake size. Combined with observations of the cyclonic wind field, this metric allows a finer analysis of the geometry of the wake in relation to the dynamics of the cyclone (inner core metric, i.e Rmax & R+).
The groundbreaking Ka-band interferometric radar (KaRIn), on board the recent satellite mission SWOT, is capable of measuring the ocean surface topography at high resolution (250m/1km) over a total width of 120 km. Thanks to a 1-day repetition cycle in its initial deployment phase (until July 2023), we have seized this unique opportunity to analyse the evolution of the wake of Typhoon Mawar, with an unprecedented temporal resolution. These first results highlight the unique ability of SWOT to observe and confirm, using a single repeated-orbit track, 1) the westward deviation of the surface anomalies, that was found in agreement with previous estimates of ~0.1°/day, and 2) the persistence of these signatures over more than 40 days. In a second time, Different pre-cyclonic averages can be also easily derived to dissociate and understand the interactions between the wake of Mawar and that of Guchol, which occurs around ten days later. A barycentric approach was used to monitor and estimate the surface anomalies induced by the two storms. Finally, the use of the current recurrence cycle (21 days) results in a larger spatial sampling of the SSHAs (2023-2024 cases) and a better picture of the wake size. Combined with observations of the cyclonic wind field, this metric allows a finer analysis of the geometry of the wake in relation to the dynamics of the cyclone (inner core metric, i.e Rmax & R+).