The Role of WISHE in the Rapid Intensification of Tropical Cyclones

• Published in: Journal of the atmospheric sciences Vol. 77; no. 9; pp. 3139 - 3160
• Main Authors: Cheng, Chieh-Jen, Wu, Chun-Chieh
• Format: Journal Article
• Language: English
• Published: Boston American Meteorological Society 01.09.2020
• Subjects: Amplification; Convection; Convective activity; Convective instability; Cyclones; Equivalent potential temperature; Heat; Heat exchange; Heat flux; Heat transfer; Hurricanes; Potential temperature; Stability; Surface fluxes; Surface stability; Tropical climate; Tropical cyclones; Wind effects
• ISSN: 0022-4928; 1520-0469
• DOI: 10.1175/JAS-D-20-0006.1

Abstract This study examines the role of surface heat fluxes, particularly in relation to the wind-induced surface heat exchange (WISHE) mechanism, in the rapid intensification (RI) of tropical cyclones (TCs). Sensitivity experiments with capped surface fluxes and thus reduced WISHE exhibit delayed RI and weaker peak intensity, while WISHE could affect the evolutions of TCs both before and after the onset of RI. Before RI, more WISHE leads to faster increase of equivalent potential temperature in the lower levels, resulting in more active and stronger convection. In addition, TCs in experiments with more WISHE reach a certain strength earlier, before the onset of RI. During the RI period, more surface heat fluxes could provide convective instability in the lower levels, and cause a consequent development in the convective activity. More efficient intensification in a TC is found with higher surface heat fluxes and larger inertial stability, leading to a stronger peak intensity, more significant and deeper warm core in TC center, and the axisymmetrization of convection in the higher levels. In both stages, different levels of WISHE alter the thermodynamic environment and convective-scale processes. In all, this study supports the crucial role of WISHE in affecting TC intensification rate for TCs with RI.