Intensification of tilted atmospheric vortices by asymmetric diabatic heating

Abstract

Päschke et al. (JFM, 701, 137{170 (2012)) studied the nonlinear dynamics of strongly tilted vortices subject to asymmetric diabatic heating by asymptotic methods. They found, i.a., that an azimuthal Fourier mode 1 heating pattern can intensify or attenuate such a vortex depending on the relative orientation of tilt and heating asymmetries. The theory originally addressed the gradient wind regime which, asymptotically speaking, corresponds to vortex Rossby numbers of order O(1) in the limit. Formally, this restricts the appicability of the theory to rather weak vortices in the near equatorial region. It is shown below that said theory is, in contrast, uniformly valid for vanishing Coriolis parameter and thus applicable to vortices up to hurricane strength. The paper's main contribution is a series of three-dimensional numerical simulations which fully support the analytical predictions.