9:15 AM - 9:30 AM
[AAS04-02] Observed Concentric Eyewalls of Supertyphoon Hinnamonor (2022)
Keywords:Typhoon, Concentric eyewalls, Radar observation
Intense tropical cyclones (TCs) often exhibit multiple concentric eyewalls (CEs) (Willoughby et al. 1982, Kuo et al. 2009). Understanding CE processes are important, because CEs are frequently accompanied by changes of TC intensity and structure (Willoughby et al. 1982; Black and Willoughby 1992).
On 30 August 2022, Typhoon Hinnamonor (2022), which was traveling westward over the sea south of Japan, developed into an uppermost class intense typhoon with a minimum central pressure of 920 hPa according to the Regional Specialized Meteorological Center (RSMC) besttrack datasets. A compact supertyphoon Hinnamonor entered the observation range of ground-based radar stations at Okinawa and built distinct CE structures. We used high-spatiotemporal-resolution data from the ground-based radars to examine the temporal evolution of the CE processes. Composite rain intensity and echo-top height data obtained by Japan Meteorological Agency weather radars had spatial resolutions of 1 km and 2.5 km, respectively, and 10-minute time intervals. Ground-based S-band radar observations were collected by the U.S. Next-Generation Weather Radar (NEXRAD) at Kadena Air Base, Okinawa. The radar data with scanning volumes at elevation angles (0.5–10.0°) and 5–6 minute intervals were converted to 1-km-mesh plan position indicator (PPI) and constant-altitude PPI (CAPPI) displays.
In a moderate south-southeastward vertical wind shear of 4.7 m s−1, Hinnamonor at peak intensity built a distinct stationary band complex (SBC) downshear of the storm inner core. The SBC traveled around the inner core and formed an axisymmetric secondary eyewall. A moat was apparent a few hours after secondary eyewall formation. After the CE structure was completed, subsequent rainbands successively appeared in the down-to-left shear quadrants and followed the SBC as they developed vast anvil clouds and stratiform regions. When the western half of the core region of Hinnamonor was covered by the well-developed anvil cloud, the secondary eyewall started contracting. Doppler velocity analyses showed that each rainband of the secondary eyewall was accompanied by high-wind regions, and the second wind maxima and associated convection intensified as the high-wind regions merged. When the core region was surrounded by multiple well-developed rainbands with broad anvil clouds, the inner eyewall weakened rapidly.
(Acknowledgements: This work was supported by the Japan Society for the Promotion of Science KAKENHI grant numbers 20H05166 and 19H05696.)
On 30 August 2022, Typhoon Hinnamonor (2022), which was traveling westward over the sea south of Japan, developed into an uppermost class intense typhoon with a minimum central pressure of 920 hPa according to the Regional Specialized Meteorological Center (RSMC) besttrack datasets. A compact supertyphoon Hinnamonor entered the observation range of ground-based radar stations at Okinawa and built distinct CE structures. We used high-spatiotemporal-resolution data from the ground-based radars to examine the temporal evolution of the CE processes. Composite rain intensity and echo-top height data obtained by Japan Meteorological Agency weather radars had spatial resolutions of 1 km and 2.5 km, respectively, and 10-minute time intervals. Ground-based S-band radar observations were collected by the U.S. Next-Generation Weather Radar (NEXRAD) at Kadena Air Base, Okinawa. The radar data with scanning volumes at elevation angles (0.5–10.0°) and 5–6 minute intervals were converted to 1-km-mesh plan position indicator (PPI) and constant-altitude PPI (CAPPI) displays.
In a moderate south-southeastward vertical wind shear of 4.7 m s−1, Hinnamonor at peak intensity built a distinct stationary band complex (SBC) downshear of the storm inner core. The SBC traveled around the inner core and formed an axisymmetric secondary eyewall. A moat was apparent a few hours after secondary eyewall formation. After the CE structure was completed, subsequent rainbands successively appeared in the down-to-left shear quadrants and followed the SBC as they developed vast anvil clouds and stratiform regions. When the western half of the core region of Hinnamonor was covered by the well-developed anvil cloud, the secondary eyewall started contracting. Doppler velocity analyses showed that each rainband of the secondary eyewall was accompanied by high-wind regions, and the second wind maxima and associated convection intensified as the high-wind regions merged. When the core region was surrounded by multiple well-developed rainbands with broad anvil clouds, the inner eyewall weakened rapidly.
(Acknowledgements: This work was supported by the Japan Society for the Promotion of Science KAKENHI grant numbers 20H05166 and 19H05696.)