A cloud-resolving model is used to examine the intensification of tilted tropical cyclones from depression to hurricane strength over relatively cool and warm oceans under idealized conditions where environmental vertical wind shear has become minimal. Variation of the SST does not substantially change the time-averaged relationship between tilt and the radial length scale of the inner core, or between tilt and the azimuthal distribution of precipitation during the hurricane formation period (HFP). By contrast, for systems having similar structural parameters, the HFP lengthens superlinearly in association with a decline of the precipitation rate as the SST decreases from 30° to 26
Three idealized high‐resolution simulations of tropical storm formation from a weak vortex are analyzed. The three simulations include a case using warm rain microphysics, a similar case in which surface friction is omitted, and a case in which ice microphysics is used. The goal is to understand the mechanisms controlling the intensity and distribution of convection in the formation process in each of these cases. Simulations of convection in weak temperature gradient convective models show that a combination of low to middle tropospheric moist convective instability, the saturation fraction or column relative humidity, and the surface moist entropy flux explain a high percentage of the variance in precipitation and lower tropospheric vertical mass flux. Tropical cyclones differ from other convective environments in that intense frictional convergence occurs in the boundary layer. Adding a measure of convective inhibition to account for this process enables the lower tropospheric mass flux to be predicted even in the core regions of the simulated tropical cyclones. These results are pertinent to the development of more accurate convective parameterizations for large‐scale models.
more » « less- NSF-PAR ID:
- 10460637
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Advances in Modeling Earth Systems
- Volume:
- 11
- Issue:
- 6
- ISSN:
- 1942-2466
- Page Range / eLocation ID:
- p. 1582-1599
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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