25th Conference on Hurricanes and Tropical Meteorology

Tuesday, 30 April 2002: 11:45 AM
Comparison of Hurricane intensity as realized in an axisymmetric model with MPI theory
John Persing, Colorado State University, Fort Collins, CO; and M. T. Montgomery
Poster PDF (582.5 kB)
The language of hurricane intensity theory is used to assess the important controls and resolution dependence of intensity in axisymmetric numerical models. Specifically, the energetically-based maximum intensity theory (E-MPI) of K. Emanuel is used since it has many dynamical elements and is constructed solely on axisymmetric principles. Certain elements of the E-MPI theory are found difficult to apply to model output. One example is the value of boundary layer relative humidity, since the tendency of one cloud-resolving axisymmetric model (the Rotunno and Emanuel 1987 model) is to saturate the lowest grid level. In this case, the assumptions of E-MPI can be relaxed and a point in the derivation can be found where relative humidity does not appear. This earlier point in the derivation is not a new a priori MPI, but rather a local diagnosis of the assumptions used to derive E-MPI. Discrepancies between the assumptions of E-MPI and the modeled intensity of the storm point to the important physical processes in the model that regulate intensity. We see this work as a first step toward analyzing the processes that regulate intensity in more realistic three-dimensional cloud-resolving models.

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