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Title: An Analytical Model for Tropical Cyclone Outer-Size Expansion on the f Plane
Abstract Tropical cyclones are known to expand to an equilibrium size on thefplane, but the expansion process is not understood. In this study, an analytical model for tropical cyclone outer-size expansion on thefplane is proposed. Conceptually, the storm expands because the imbalance between latent heating and radiative cooling drives a lateral inflow that imports absolute vorticity. Volume-integrated latent heating increases more slowly with size than radiative cooling, and hence, the storm expands toward an equilibrium size. The predicted expansion rate is given by the ratio of the difference in size from its equilibrium valuert,eqto an environmentally determined time scaleτrtof 10–15 days. The model is fully predictive if given a constantrt,eq, which can also be estimated environmentally. The model successfully captures the first-order size evolution across a range of numerical simulation experiments in which the potential intensity andfare varied. The model predictions of the dependencies of lateral inflow velocity and expansion rate on latent heating rate are also compared well with numerical simulations. This model provides a useful foundation for understanding storm size dynamics in nature.  more » « less
Award ID(s):
1945113
PAR ID:
10593541
Author(s) / Creator(s):
;
Publisher / Repository:
American Meteorological Society
Date Published:
Journal Name:
Journal of the Atmospheric Sciences
Volume:
81
Issue:
7
ISSN:
0022-4928
Page Range / eLocation ID:
1097 to 1125
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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