Tropical Cyclone Simulations with the Betts Convective Adjustment Scheme. Part II: Sensitivity Experiments

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  • 1 Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina
  • | 2 Hurricane Research Division, AOML/NOAA, Miami, Florida
  • | 3 Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, North Carolina
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Abstract

Extensive sensitivity experiments with an axisymmetric tropical cyclone model that includes the Bets convective parameterization scheme are carded out. The sensitivity of the model storm evolution to the convective adjustment parameters is studied. These results show that the model storm leads to earlier development as the adjustment time scale becomes small and the stability weight on the moist adiabat in the lower atmosphere is increased. The model storm evolution is very sensitive to variations in the saturation pressure departure at the lowermost model integer level and the storm at mature stage has a lower central pressure as the magnitude of the saturation pressure departure is increased. The adjustment parameters affect the grid-scale precipitation as well as the convective precipitation and the precipitation is especially sensitive to changes in the saturation pressure departure.

Sensitivity of the model to variations in the sea surface temperature, latitude, initial vortex amplitude, initial moisture distribution, and radiation is also investigated. The results of the numerical simulations are similar to previous studies. Sensitivity studies with various horizontal resolutions show that the subgrid-scale heating becomes a larger fraction of the total heating as the horizontal grid size is increased.

Abstract

Extensive sensitivity experiments with an axisymmetric tropical cyclone model that includes the Bets convective parameterization scheme are carded out. The sensitivity of the model storm evolution to the convective adjustment parameters is studied. These results show that the model storm leads to earlier development as the adjustment time scale becomes small and the stability weight on the moist adiabat in the lower atmosphere is increased. The model storm evolution is very sensitive to variations in the saturation pressure departure at the lowermost model integer level and the storm at mature stage has a lower central pressure as the magnitude of the saturation pressure departure is increased. The adjustment parameters affect the grid-scale precipitation as well as the convective precipitation and the precipitation is especially sensitive to changes in the saturation pressure departure.

Sensitivity of the model to variations in the sea surface temperature, latitude, initial vortex amplitude, initial moisture distribution, and radiation is also investigated. The results of the numerical simulations are similar to previous studies. Sensitivity studies with various horizontal resolutions show that the subgrid-scale heating becomes a larger fraction of the total heating as the horizontal grid size is increased.

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