Tropical Cyclone Intensity in Vertical Wind Shear

Abstract

Abstract The structure and intensity changes of tropical cyclones (TCs) in environmental vertical wind shear (VWS) are investigated in this study using the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5). Triply nested domains of 36-, 12-, and 4-km resolution are used with fully explicit moisture physics in the 4-km domain. Idealized environments with easterly shears of 2, 4, 6, 8, and 10 m s−1 between 800 and 200 hPa are applied on an f plane. Under small values of VWS (2 and 4 m s−1), the TC intensities are similar to that of the control (CTRL; i.e., no VWS) after initial adjustments. The TCs under 6 and 8 m s−1 of VWS are not as intense, although they do not weaken during the simulation. On the other hand, the TC in 10 m s−1 of VWS weakened significantly. Given the same VWS, the TC intensity is also found to be sensitive to TC size. Experiments with TCs with a smaller radius of 15 m s−1 wind reveal that while the TC in 2 m s−1 of ...