Solutions of the Eliassen balance equation for inertially and/or symmetrically stable and unstable vortices
Author
Wang, Shanghong
Montgomery, Michael T.
Smith, Roger K.
Date
2021Metadata
Show full item recordAbstract
Two methods for solving the Eliassen equation for the corresponding balanced
secondary circulation of a numerically simulated, high-resolution tropical
cyclone vortex are compared. In idealized calculations for a symmetrically stable
vortex, both methods (successive overrelaxation [SOR] and multigrid) converge
and the solutions are broadly similar. In more typical cases, where the vortex
has regions of inertial or symmetric instability, it is necessary to coarsen the data
from the numerical simulation to determine the balanced secondary circulation.
A convergent solution can be obtained with the multigrid method for a finer
grid spacing than with the SOR method. However, the multigrid method fails to
converge when the vertical grid spacing is similar to that of the numerical simulation.
Results using both methods confirm the inability of the balance formulation
to capture the strong inflow and resulting tangential wind spin-up in the
frictional boundary layer during a period of rapid intensification. Typical tropical
cyclone simulations show an inflow layer just beneath the upper-level outflow
layer, and the corresponding balanced secondary circulation may show such
an inflow layer also. However, caution is called for in attributing this inflow
layer to a balanced flow response driven by the distribution of diabatic heating
and tangential momentum forcing. Our study suggests that this inflow layer is
likely an artifact of the ad hoc regularization procedure that is necessary to keep
the Eliassen equation globally elliptic in regions of inertial and/or symmetric
instability.
Description
17 USC 105 interim-entered record; under review.
The article of record as published may be found at http://dx.doi.org/10.1002/qj.4098
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.Collections
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