Extended Abstract (204K)4A.7
How Much Vertical Shear Can A Well-Developed Tropical Cyclone Resist?
Yuqing Wang, International Pacific Research Center, University of Hawaii, Honolulu, HI; and M. T. Montgomery and B. Wang
Among many limiting factors, the unfavorable environmental conditions, especially the vertical shear-induced asymmetry in the inner core region, have been postulated as the primary impediment to a tropical cyclone reaching its maximum potential intensity (MPI). A related question is how strong vertical shear a mature tropical cyclone can resist. Observations from the western North Pacific and other regions show that in most circumstances strong tropical cyclones can resist vertical shear as strong as 15-20 m/s. Recent theoretical studies demonstrate that even dry tropical-cyclone-like vortex can survive against modest vertical shear. However, the numerical study by Frank and Ritchie (2001) showed that even in a 5m/s vertical shear a strong tropical cyclone could be substantially weakened in two days. They attributed the weakening of the storm to the outward transport of high equivalent potential temperature at upper levels due to the vertical shear-induced eddies. In this study, we revisit this problem using the tropical cyclone model—TCM3. Results from a series of numerical experiments show that strong mature tropical cyclone can resist vertical shear as strong as 15 m/s, consistent with observations, while in contrast to Frank and Ritchie’s results. We suspect that there might be some problems in their experimental design. The physical mechanisms responsible for the resistance of the model tropical cyclone to vertical shear will be discussed.
Session 4A, Tropical Cyclones and Vertical Shear
Monday, 3 May 2004, 3:45 PM-5:30 PM, Le Jardin Room
Previous paper
Recorded presentation