17B.3
**Generalized moist potential vorticity diagnosed from a nonhydrostatic, axisymmetric tropical cyclone simulation
Scott A. Hausman, Colorado State University, Fort Collins, CO
We present a generalized form of the moist potential vorticity (PV) principle and use it to diagnose the PV of a simulated tropical cyclone. Using the virtual potential temperature, defined in terms of the total pressure and density (including condensate), we generalize Ertel's dry PV to a precipitating atmosphere. This generalized form of the moist PV has the following unique properties. 1) It contains all of the moisture information, therefore precipitation's effect on PV is included. 2) It eliminates the solenoidal term, thus only the diabatic and frictional terms represent material sources of PV (unlike the moist PV defined using equivalent potential temperature). 3) It reduces to the dry PV in the limit of zero moisture, therefore the dry and moist dynamics are comparable (unlike the moist PV defined using the saturated equivalent potential temperature). 4) It is invertible and satisfies the impermeability theorem of Haynes and McIntyre, thus it may be used to diagnose the balanced mass and wind fields. These properties are used to diagnose and analyze the moist PV from an axisymmetric tropical cyclone simulation performed using Ooyama's nonhydrostatic, primitive equation model with classical thermodynamics and parameterized microphysics.
Session 17B, Convective Processes III (Parallel with Sessions 17A and 17C)
Saturday, 27 May 2000, 10:30 AM-12:30 PM
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