The abnormal track of super typhoon Hinnamnor (2022) and its interaction with the upper ocean

Abstract

The upper ocean response and feedback to super typhoon Hinnamnor (2022) were systematically investigated considering multi-satellite, Array for Real-time Geostrophic Oceanography (Argo) float and reanalysis data. Hinnamnor experienced three main stages: a rapid intensification (RI) stage with a high moving speed along a westward track, a rapid weakening (RW) stage with a low moving speed along a northward sudden-turning track and a re-intensification (Re-I) stage with a moderate speed along a northward track. At the westward straight-line stage, despite the thin warm water layer (D26 < 40 m) and shallow mixed layer depth (MLD) (<20 m), its fast movement (∼8.1 m/s) tended to generate weaker sea surface temperature (SST) cooling (approximately 1 °C) and shorter cooling exposure. Consequently, the negative feedback decreased (negative feedback factor FSST:approximately−0.47to−0.20), causing Hinnamnor's rapid intensification (25 knots/6 h). Although the MLD was deeper (approximately 30 m) and the warm water layer was thicker (approximately 60 m) at the sudden-turning stage, the low translation speed (<2 m/s) tended to generate stronger SST cooling (approximately 5.6 °C) and longer cooling exposure, both of which intensified the negative feedback (FSST:approximately−0.8to−0.4), causing Hinnamnor's rapid weakening (−22 knots/6 h). At the northward stage, Hinnamnor re-intensified under a weak warm eddy with a moderate moving speed (3.6–5.4 m/s). An intriguing leftward bias in SST cooling occurred due to the preexisting cold eddy (CE) on the left side of the track. Analysis of the Argo floats in the RI and RW regions showed that the enhanced upwelling and vertical mixing yielded more significant SST cooling in the CE region at the RW stage due to the CE and low translation speed (<2 m/s). The differences between the RI and RW regions were remarkable when using the Hybrid Coordinate Ocean Model (HYCOM) global ocean model output.