Response of the Kuroshio large meander path to typhoons: a case study from a high-resolution ocean model

The path variation of the Kuroshio Large Meander (LM) induced by typhoons was studied. Using a data-assimilative high resolution ocean model, we investigated a case, in which two typhoons sequentially passed across the Kuroshio in September 2022. The results show that: (1) the Kuroshio mainstream downstream of the LM broke and shifted from a previous nearshore meander path to an offshore straight path due to the disturbance of Typhoon Nanmadol. The offshore path maintained nearly two months before the nearshore LM re-established. (2) Typhoon Muifa intruded into the Kuroshio far from the LM region. It caused no significant positional variation to the Kuroshio path. In the scenario of Nanmadol, the speed and transport of the Kuroshio increased. The Kuroshio thus flowed across the Izu Ridge and broke its previous meander path. (3) The dynamical mechanism behind the variability was transformation of kinetic energy from typhoon-induced wind energy to the mean kinetic energy of the Kuroshio through barotropic conversion, which further strengthened the Kuroshio. This case study documents a short-term but pronounced disturbance of the Kuroshio LM induced by typhoon.