89th American Meteorological Society Annual Meeting

Monday, 12 January 2009: 11:00 AM
Convective organization and the Year of Tropical Convection (YoTC)
Room 129A (Phoenix Convention Center)
Mitchell W. Moncrieff, NCAR, Boulder, CO; and D. Waliser
The central science objective of the Year of Tropical Convection (YoTC) is to quantify the effects of convective organization on the large-scale atmospheric circulation. Tropical convection has a tendency to evolve upscale and generate coherent motion systems (organized convection) up to thousands of times the size of cumulus clouds. The organization process involves fundamental physics such as convection-wave interaction, upscale cascades of mass, energy and momentum associated with the nonlinear properties of precipitating convection. Phenomena that are resilient uncertainties in weather and climate models will be examined in YoTC, such as the MJO and convectively-coupled waves, the diurnal cycle, easterly waves and tropical cyclones, the monsoon systems, and tropical-extratropical interactions. The MJO, the most complex type of tropical multiscale organization, will be the example described in this talk. Notably, convective organization is not represented by contemporary convective parameterizations, a deficiency shown by field-campaign results for the past three decades. New approaches are now at our disposal to address the convective organization problem with unprecedented comprehensiveness. Cloud-system resolving models (CRM) simulate convective organization explicitly, data from multisensor satellite and field-campaign measurements evaluate model results, and insights are available from theoretical-dynamical models. CRM simulations, model validation using satellite data, and the parameterization of mesoscale convective systems for future climate models will be described.

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