Large-Scale Circulations and Dry Tropical Cyclones in Direct Numerical Simulations of Rotating Rayleigh–Bénard Convection
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Published version
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Author(s)
Velez-Pardo, Martin
Cronin, Timothy W
Date Issued
September 1, 2023
Journal
Journal of the Atmospheric Sciences
Publisher
American Meteorological Society
Citation
Velez-Pardo, M., and T. W. Cronin, 2023: Large-Scale Circulations and Dry Tropical Cyclones in Direct Numerical Simulations of Rotating Rayleigh–Bénard Convection. J. Atmos. Sci., 80, 2221–2237.
Version
Final published version
Abstract
The organization of convection into relatively long-lived patterns of large spatial scales, like tropical cyclones, is a common feature of Earth’s atmosphere. However, many key aspects of convective aggregation and its relationship
with tropical cyclone formation remain elusive. In this work, we simulate highly idealized setups of dry convection, inspired
by the Rayleigh–Bénard system, to probe the effects of different thermal boundary conditions on the scale of organization
of rotating convection, and on the formation of tropical cyclone–like structures. We find that in domains with sufficiently
high aspect ratios, moderately turbulent (Raf 109), moderately rotating (Roc 1) convection organizes more persistently
and at larger scales when thermal boundary conditions constrain heat fluxes rather than temperatures. Furthermore, for
some thermal boundary conditions with asymmetric heat fluxes, convection organizes into persistent vortices with the essential properties of mature tropical cyclones: a warm core, high axisymmetry, a strong azimuthal circulation, and substantially larger size than individual buoyant plumes. We argue that flux asymmetry results in a persistent and localized input
of buoyancy, which allows spatially aggregated convection to sustain a warm core in a developing large-scale vortex. Crucially, the most intense and axisymmetric cyclone forms for setups where the bottom heat flux is enhanced by the nearby
flow and the top boundary is insulating, as long as the convective Rossby number is higher than about 1. Our results demonstrate the great potential for dialogue between classical turbulence research and the study of convective aggregation and
tropical cyclones.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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DOI of Published Version
https://doi.org/10.1175/JAS-D-23-0018.1
