The vortical response to penetrative convection and the associated gravity‐wave generation

Abstract

This study documents the vortical motions that arise due to penetrative convective updraughts. Using an idealized axisymmetric model of dry thermals it is shown that in a stable environment the baroclinic generation of vorticity forms a circulation that opposes updraught overshoot and manifests the first signature of gravity waves emanating from the thermal. Continued baroclinic generation of vorticity of oscillating sign completes the first full wavelength and populates the wave packet. These examples provide an alternate description of the generation of gravity waves by penetrative convection and provide further insight into the morphology of the wave source

Toward a Multiscale Approach for Computational Atmospheric Modeling

“…Figure 4d shows that the grid has been adapted to local features of the flow, which is the achievement of this development, and its potential advantage for more realistic systems. These results have a good qualitative agreement with those that were predicted by various other numerical models (e.g., see, Carpenter et al 1990;Wicker and Skamarock 1998;Bryan and Fritsch 2002;Lane 2008, and the references therein).…”

“…The number of grid points is N 5 7808 at t 5 0 min, which increases to 25 344 at t 5 33 min, confirming that the model adds or deletes grid points so that small filamentary structure of u is resolved. buoyancy gradient is associated with that of large velocity gradient (e.g., Carpenter et al 1990;Lane 2008). Figure 4d shows that the grid has been adapted to local features of the flow, which is the achievement of this development, and its potential advantage for more realistic systems.…”

“…The maximum buoyancy is 9.8 3 10 22 m s 22 at the center of the thermal, which decreases exponentially to 0 m s 22 outside the edge of the thermal. This buoyancy anomaly is equivalent to a potential temperature perturbation 3 K, which is similar to thermals in a boundary layer (Lane 2008). The evolved state of the thermal and that of the vertical velocity at t 5 12 min is presented in Figs.…”

“…This approximate form is commonly used for modeling mesoscale phenomena such as sea-breeze circulation, dry convection, etc. (e.g., Defant 1951;Martin and Pielke 1983;Alam and Lin 2008;Lane 2008), or modeling the atmospheric boundary layer (Moeng 1984). The choice of compressible, anelastic, or approximate anelastic form depends on specific applications or target atmospheric conditions.…”

Aviation Turbulence

“…This baroclinically generated vorticity would have circulation of the same sense as the vortex seen here. See Lane (2008) for a more detailed description of the formation of this vortical response, which is referred to as the 'secondary circulation' in that paper.…”