Jun Wei1*, Xin Liu1 and Dong-Xiao Wang2
1Department of Atmospheric and Oceanic Sciences, Peking University, China
2South China Sea Institute of Oceanology, CAS, China
Abstract: Relatively weak hurricane-induced cooling (< 1 ºC) is often observed in the Loop Current, while observed SST cooling is much stronger in the Kuroshio. This was previously attributed to strong advection effects by the Loop Current. Based on a budget analysis, this study quantitatively diagnoses the dynamic and thermal response of the Kuroshio to typhoon Megi and 4 additional TCs, which produce up to ~3 ºC SST cooling within the Kuroshio itself. The results show that the surface thermal response of the Kuroshio is a wind-induced temperature cooling primarily due to vertical mixing (up to 96%). The dynamic response of the Kuroshio depends not only on TC conditions (intensity and wind direction), but also on pre-storm ocean conditions (e.g. ocean mixed layer depth, baroclinicity and current velocity). Differently from the open ocean where the ocean gains kinetic energy mainly from wind stress work, the Kuroshio can obtain greater kinetic energy from its baroclinic pressure work, especially in the upper ocean. The strong SST cooling observed in the Kuroshio region is therefore likely associated with the kinetic energy extracted from the Kuroshio baroclinic potential energy, which greatly enhances local vertical mixing.
Citation: Wei, J., X. Liu and D. Wang, 2014. Dynamic and thermal responses of the Kuroshio to typhoon Megi (2004). Geophys. Res. Lett., 41, doi:10.1002/2014GL061706