讲座简介:

Relatively weak SST cooling (< 1 ºC) was often observed in the Loop Current induced by moving hurricanes, while observed SST cooling are much stronger in the Kuroshio. This was previously attributed to strong advection effect of the Loop Current. Based on budget analysis, this study quantitatively diagnosed thermal and dynamic responses of the Kuroshio to tropical cyclones (TCs), which produced up to ~3 ºC SST cooling within the Kuroshio. The results showed that the thermal response of the Kuroshio is showed as wind-induced temperature cooling primarily due to vertical mixing (up to 96%) instead of advection effect. Dynamic response of the Kuroshio depends not only on TC condition (intensity and wind direction), but also pre-storm ocean conditions (e.g. ocean mixed layer depth, baroclinicity and current velocity). Different from the open ocean where ocean gains kinetic energy mainly from wind stress work (WND), the Kuroshio can obtain greater kinetic energy from its baroclinic pressure work (PWH), especially in the upper ocean. Strong SST cooling observed in the Kuroshio region is likely associated with kinetic energy extracted from baroclinic potential energy of the Kuroshio, which greatly enhances local vertical mixing.