Extended Abstract (176K)16B.6
Convectively Generated Inertial-Gravity Waves and Multi-Scale Organization of Convection
Mitchell W. Moncrieff, NCAR, Boulder, CO; and C. Liu
The interaction between convection and the environment is strongly affected by inertial-gravity waves. The effects of latent heating and inertial-gravity waves on numerically simulated convective cloud systems are examined. We first examine the nonlinear response of an initially motionless, uniformly stratified, dry atmosphere to steady heating. Planetary rotation confines the subsidence-induced adiabatic warming to the neighborhood of the heated region on a time scale comparable to the lifetime of mesoscale convective systems. In a moist atmosphere, rotation-induced localized descent stabilizes and dries the near environment and decreases the convective available potential energy. The tropics is therefore a preferred region for convective clustering. This hypothesis is tested in two sets of 12-day convection-resolving simulations on f-planes representative of the tropics, sub-tropics and midlatitudes. Convection is maintained by radiative cooling and surface fluxes of heat and moisture. In a motionless mean state, convective clustering is most prominent in the tropics. In constant easterly flow, convection organizes on three scales. Eastward-propagating convectively coupled gravity waves generate large-scale envelopes of cloudiness. Embedded within these envelopes are westward-traveling mesoscale convective systems that, in turn, contain westward-traveling deep convective cores. Clustering is prevalent in the tropics.
Session 16B, Convection, waves, and precipitation VII
Friday, 7 May 2004, 8:00 AM-9:30 AM, Napoleon I Room
Previous paper
Recorded presentation