29 Propagating Convective Systems and Gravity Waves

Tuesday, 6 August 2013
Holladay-Halsey (DoubleTree by Hilton Portland)
Todd P. Lane, The University of Melbourne, Melbourne, Victoria, Australia; and M. W. Moncrieff

Theoretical models of the steady circulation of organized convection and squall lines have identified the important features that help maintain their overarching structure and longevity. The most common of these models is the trailing stratiform archetype, which contains front to rear ascending inflow, an established mesoscale downdraft circulation, and a cold pool / density current that helps define the system propagation speed. However, this archetype does not necessarily explain all types of mesoscale convective systems, especially in moist environments where evaporatively driven cold pools are weak. Moreover, questions remain about the role of gravity waves in creating organized systems or helping define their propagation speed.

In this study we present a series of idealized model simulations of self-organizing convection in a moist, low convective inhibition environment. The convective regimes are long-lived but they lack mesoscale downdraft circulations and their organizational characteristics differ from the common trailing stratiform archetype. Gravity waves are shown to help determine the propagation speed of the systems. In this presentation we will describe the three-dimensional structure and dynamics of the convective regimes and discuss them in the context of existing models of organized convective systems.

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