The Role of WISHE in the Rapid Intensification of Super Typhoon Hinnamnor (2022)

Abstract

In this study, the role of the wind-induced surface heat exchange (WISHE) in rapid intensification (RI) is investigated in a numerical model. During the development of Hinnamnor, its energy growth rate (EGR) continuously increases as RI progresses. After Hinnamnor reaches its maximum intensity, although its EGR weakens a little, it remains relatively large. If it had not been for the influence of the external environment (such as the tropical depression), its maximum intensity would have been far greater than the actual maximum intensity (140 knots). As the WISHE effect progressively weakens, the number of convective bursts (CBs) gradually diminishes. This, in turn, gives rise to a corresponding weakening of the warm core and a subsequent delay in the start time of the axisymmetrization of the inner core, thereby affecting the intensification rate of the vortex and the final maximum intensity. Consequently, the start time of RI is also correspondingly postponed. Differing from the maximum potential intensity theory, when the EGR approaches zero, a TC does not immediately reach its maximum intensity. Instead, it attains its peak intensity approximately 12 hr later. During this additional 12 hr period, the number of CBs continues to increase, the warm core keeps on strengthening and the inner core continues its progress toward axisymmetric until the end of the RI process. This indicates that the dynamical and thermodynamical processes are also of great importance during the RI stage.