[A-AS06] Advances in Tropical Cyclone Research: Past, Present, and Future

[AAS06-P03] Effects of Significant Wave Height on CYGNSS Typhoon Wind Speed Estimations

*Kaoru Ichikawa¹, Dexin Gu² (1.Research Institute for Applied Mechanics, Kyushu University, 2.Interdisciplinary Graduate School of Engineering Sciences, Kyushu University)

Keywords:Remote Sensing, asymmetry of typhoon winds, Cyclone GNSS microsatellites

Although synoptic wind fields around typhoons and cyclones are vital for understanding, our observations are limited. At present, only AMSR2 and CYGNSS satellites can provide synoptic observations in areas of high winds. The CYGNSS system, comprises eight microsatellites that measure reflected GNSS signals at the sea surface, estimates wind speeds continuously (at 12 min intervals), which can provide temporally averaged field in contrast to AMSR2's snapshot wind field observations.
In 2021, CYGNSS has modified its wind speed retrieval algorithm (Version 3.1) to include significant wave height (SWH) correction. Since wind direction and wave propagation directions vary around a moving typhoon, SWH field becomes significantly complex and asymmetric around the typhoons. In this presentation, we investigate effects of SWH corrections on CYGNSS winds around typhoons Jebi and Trami, by comparing previous version (Version 3.0) and new version products.
In general, new products accounting SWH correction show right-strengthened wind patterns around typhoon centres, which are consistent with AMSR2 winds and numerical model results (ERA5 and CFSRv2). These improvements, however, are not the same in two typhoons whose movement speeds are different; fast-moving Jebi shows more significant improvements.
Dependencies on moving speeds and direction of the typhoon centre, and maximum wind speeds will be further examined with other typhoon cases.