Transient moist baroclinic instability

Abstract

The non-modal transient properties of the Eady baroclinic model with a simple heating parameterization are examined. The time-dependent non-modal behavior of the moist baroclinic model is investigated by calculating the energy amplification of optimal perturbations for relevant time-scales and by calculating the energy evolution of random initial conditions. Enhanced non-modal growth on time-scales of 1-2 days is present on all length-scales considered. Exponentially neutral length-scales present algebraic growth which is substantially enhanced in the presence of condensational heating. On time-scales of 1-2 days, maximum growth occurs on shorter length-scales than those predicted by previous normal mode calculations. Heating is found to reduce the time required for uncorrelated random perturbations to organize and grow, though for moderate heating, this time is still relatively long.