27th Conference on Hurricanes and Tropical Meteorology


Gravity wave mechanisms in propagating diurnal convection

Brian Mapes, Univ. of Miami/RSMAS, Miami, FL

Propagating diurnal convective rainfall features are found in many tropical areas, especially near coastlines and mountain ranges which produce repeated diurnal forcings. Such propagating features can be viewed as moist generalizations of "land-sea breeze" or "mountain-valley breeze" phenomena, but in a broad sense, involving stratified (gravity-wave) dynamics, not just hot air rising in an unstratified boundary layer.

Some detailed studies of this mechanism of diurnal variability will be reviewed, from Southeast Asia/ Indonesia, the Panama Bight (modeling), and the Bay of Bengal. The driving mechanism seems to be elevated dry sensible heating over land, especially over high terrain, embedded within a broader-scale stratified atmosphere (like the tropical marine environment). The modulation of convection by these vertically short waves gives important clues to how low-level conditions modulate deep convection. This modulation mechanism is also important to understanding free (non-diurnal) dynamical waves of convection in the tropics.


Session 14D, Special Session: Diurnal Variability of Precipitation - Regional Observations
Thursday, 27 April 2006, 3:30 PM-5:30 PM, Regency Grand BR 1-3

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