Explicit simulation of the evolution and inner-core structures of Hurricane Bonnie (1998).

摘要

This dissertation research consists of the development of an algorithm to construct a hurricane initial vortex, a 5-day control simulation and verification, diagnostic analyses of the hurricane evolution and asymmetric structures, and the sensitivity to cloud microphysics parameterizations and sea surface temperature (SST).; An algorithm to construct hurricane vortices is developed using the Advanced Microwave Sounding Unit (AMSU-A) data. Under the rain-free atmospheric conditions, the temperature profile could be retrieved with a root mean square error of 1.5°C. The rotational and divergent winds are obtained by solving the nonlinear balance and Omega equations using the large-scale analysis as the lateral boundary conditions. The so-derived temperature and wind fields associated with Bonnie compare favorably to the dropsonde observations taken in the vicinity of the storm.; A 5-day explicit simulation of Hurricane Bonnie is performed using the hurricane vortex that is retrieved from the Advanced Microwave Sounding Unit-A (AMSU-A) satellite measurements. The simulated track is within 3° lat/lon of the best track at the end of the 5-day integration, but with the landfalling point close to the observed. The model also reproduces reasonably well the hurricane intensity, asymmetries, as well as the vertical structures of dynamic and thermodynamic fields in the eye and eyewall.; The diagnostic analyses are conducted to study the vertical wind shear effects on hurricane intensity and asymmetric structures using the control simulation data. It is shown that the approach of a strong upper-level northwesterly flow tends to generate mass convergence, subsidence warming and drying, thereby suppressing the development of deep convection in the western eyewall. Both the observed and simulated storms appear to exhibit an eyewall replacement scenario prior to its landfall in which it weakens as double eyewalls appear, and then it re-intensifies as its inner eyewall diminishes and a concentric eyewall develops. The sensitivity of the hurricane intensity and cloud/precipitation structures to the cloud microphysics schemes and SST is studied.