J. Atmos. Sci., in press.
Allison A. Wing
Suzana J. Camargo Adam H. Sobel Abstract
We perform 3-d cloud-resolving simulations of radiative-convective equilibrium
(RCE) in a rotating framework, with interactive radiation and surface
fluxes and fixed sea surface temperature. We allow a tropical cyclone to develop
spontaneously from a homogeneous environment, rather than initializing
the circulation with a weak vortex or moist bubble (as is often done in numerical
simulations of tropical cyclones). We compare the resulting tropical
cyclogenesis to the self-aggregation of convection that occurs in non-rotating
RCE simulations. We quantify the feedbacks leading to cyclogenesis using a
variance budget equation for the column integrated frozen moist static energy.
In the initial development of a broad circulation, feedbacks involving longwave
radiation and surface enthalpy fluxes dominate, which is similar to the
initial phase of non-rotating self-aggregation. Mechanism denial experiments
are also performed to determine the extent to which the radiative feedbacks
that are essential to non-rotating self-aggregation are important for tropical
cyclogenesis. We find that radiative feedbacks significantly aid the evolution
to cyclogenesis, but are not strictly necessary.
Lamont-Doherty Earth Observatory
of Columbia University, Palisades, NY.
Lamont-Doherty Earth Observatory
of Columbia University, Palisades, NY.
Department of Applied Physics and Applied Mathematics, Department of Earth and Environmental Sciences, and Lamont-Doherty Earth Observatory,
Columbia University, New York, NY