Kinetic energy budgets in different quadrants during tropical cyclone recurvature: A case study of Typhoon Rumbia (2018)

Abstract

The contributions of divergent and rotational winds to the kinetic energy (KE) budget in different quadrants in the domain of Typhoon Rumbia (2018) with record-breaking duration are analyzed during its recurvature. The relative importance of the rotational and divergent kinetic components represented by Kr and Kd, respectively, in the KE budget are investigated. Distinguished from previous kinetic budget analyses over the entire target domain, Kr and Kd are investigated in the four quadrants around typhoon centers to study their individual contributions along typhoon tracks. It is found that the KE budget by the divergent wind is of vital importance during typhoon recurvature. KE, Kr and Kd are asymmetric around Typhoon Rumbia with maximum values occupying in the northern quadrants. The maintenance of the anticyclonic circulation at high levels before Rumbia recurvature is mainly resulted from the increase of Kr and the decrease of Kd. Kd at middle and high levels starts to propagate downwards, especially in the northeast quadrant starts. This phenomenon is prior to the recurvature which leads to the increase of Kd and decrease of KE and Kr at low levels.