Effects of Parameterized Diffusion on Simulated Hurricanes
- 1 July 2012
- journal article
- Published by American Meteorological Society in Journal of the Atmospheric Sciences
- Vol. 69 (7), 2284-2299
- https://doi.org/10.1175/jas-d-11-0204.1
Abstract
In this study the authors analyze and interpret the effects of parameterized diffusion on the nearly steady axisymmetric numerical simulations of hurricanes presented in a recent study. In that study it was concluded that horizontal diffusion was the most important control factor for the maximum simulated hurricane intensity. Through budget analysis it is shown here that horizontal diffusion is a major contributor to the angular momentum budget in the boundary layer of the numerically simulated storms. Moreover, a new scale analysis recognizing the anisotropic nature of the parameterized model diffusion shows why the horizontal diffusion plays such a dominant role. A simple analytical model is developed that captures the essence of the effect. The role of vertical diffusion in the boundary layer in the aforementioned numerical simulations is more closely examined here. It is shown that the boundary layer in these simulations is consistent with known analytical solutions in that boundary layer depth increases and the amount of “overshoot” (maximum wind in excess of the gradient wind) decreases with increasing vertical diffusion. However, the maximum wind itself depends mainly on horizontal diffusion and is relatively insensitive to vertical diffusion; the overshoot variation with vertical viscosity mainly comes from changes in the gradient wind with vertical viscosity. The present considerations of parameterized diffusion allow a new contribution to the dialog in the literature on the meaning and interpretation of the Emanuel potential intensity theory.Keywords
This publication has 29 references indexed in Scilit:
- Effects of Surface Exchange Coefficients and Turbulence Length Scales on the Intensity and Structure of Numerically Simulated HurricanesMonthly Weather Review, 2012
- Evaluation of an Analytical Model for the Maximum Intensity of Tropical CyclonesJournal of the Atmospheric Sciences, 2009
- The Maximum Intensity of Tropical Cyclones in Axisymmetric Numerical Model SimulationsMonthly Weather Review, 2009
- Exact vortex solutions of the Navier–Stokes equations with axisymmetric strain and suction or injectionJournal of Fluid Mechanics, 2009
- Observed Structure, Evolution, and Potential Intensity of Category 5 Hurricane Isabel (2003) from 12 to 14 SeptemberMonthly Weather Review, 2008
- The Navier-Stokes EquationsPublished by Cambridge University Press (CUP) ,2006
- Sensitivity of High-Resolution Simulations of Hurricane Bob (1991) to Planetary Boundary Layer ParameterizationsMonthly Weather Review, 2000
- Some Aspects of Hurricane Inner-Core Dynamics and EnergeticsJournal of the Atmospheric Sciences, 1997
- An Air-Sea Interaction Theory for Tropical Cyclones. Part I: Steady-State MaintenanceJournal of the Atmospheric Sciences, 1986
- On the Ekman Layer in a circular VortexJournal of the Meteorological Society of Japan. Ser. II, 1971