P2.4 Vertical velocity composites of Mesoscale Convective Systems observed during BAMEX

Wednesday, 12 July 2006
Grand Terrace (Monona Terrace Community and Convention Center)
James Correia Jr., SPC, Norman, OK; and R. W. Arritt

Vertical velocity calculations from dropsonde data are used along with thermodynamic composites from Mesoscale Convective Systems. The composites reveal typical structures associated with MCS wake soundings otherwise known as "onion" soundings. The vertical velocity structures indicate composites downdrafts starting above the freezing level in the transition zone of the MCS and slopes toward the ground as the wake is approached. Mean vertical velocities approach 1 m/s throughout this layer. In most cases the freezing level does not act as an interface between descending and ascending motions. The vertical velocity profiles suggest that evaporative and sublimative cooling are thedominant mechanism in driving the downdrafts. The role of the rear inflow jet and evolution of onion type soundings will be discussed at the conference. Additionally, details of the vertical velocity "retrieval" will be discussed, including verification of the method with other field project data (RICO, IHOP, and RAINEX).
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