A Study of the Vortex Filament Pool Left by a Super Typhoon

Enhancing typhoon forecasts hinges on a deeper understanding of the upper-ocean’s response and feedback mechanisms to typhoons. Presently, our knowledge of typhoon-ocean interactions is largely derived from low-resolution numerical simulations (often >10 km) and limited observations, which inadequately capture submesoscale processes (SPs) in the ocean. Connecting extreme typhoons to upper-ocean SPs remains a challenge. This study reveals the formation of a distinctive vortex filament pool (VFP) in high-resolution (∼1.2 km) numerical experiments. The experiments show that under specific conditions, typhoons can generate this visually striking phenomenon, displaying SP dynamics and kinematics typical of the upper ocean, with Rossby numbers and the nondimensional strain and divergence rates exceeding 2. The VFP formation is mainly driven by strain-induced frontogenesis linked to the flow generated by Typhoon Nangka after a major turn. Initially, the pool consists of many near-parallel filaments, but processes such as merging, stretching, and destabilization subsequently occur lead to numerous small vortices with a mean radius of ∼13 km. While the high-resolution numerical experiments highlight phenomena requiring observational validation, they suggest the presence of natural processes previously undetectable with low-resolution models and limited observations. This study underscores the need for enhanced observations and numerical models to better understand refined ocean dynamical processes.