The 23rd Conference on Hurricanes and Tropical Meteorology

4C.3
THREE-DIMENSIONAL STRUCTURE OF SQUALL-LINE WAKES IN COARE AND GATE

Sharon A. Lewis, NOAA/NWS, Boulder, CO; and M. A. LeMone

Combined aircraft Doppler-radar and in-situ data in TOGA COARE provide the opportunity to relate details on the structure of the boundary layer modified by convective systems to the convective environment. Using the 20 February squall system as our primary example, we compare wake boundary-layer structure in TOGA COARE squall systems to that of documented GATE squall lines, particularly that of 12 September. While the GATE and COARE systems bear broad similarities -- namely a broad wake of modified air behind the leading squall line, there are interesting differences. Some of these differences are real, and some may reflect different sampling strategies. Most remarkably, convection (albeit rapidly weakening) was observed within the wake region of the COARE systems. Second, there was evidence of convective-scale minima in theta_e, sometimes, but not always, associated with divergence. These minima, documented as low as 150 m above the surface, were roughly equal to the lowest theta_e in the environmental sounding. Third, mixed layers < 100 m deep were observed behind the squall line in the stratiform region. Fourth, there was considerable variability in boundary-layer properties that reflected the complex history of the air that eventually reached the lowest levels.

The 23rd Conference on Hurricanes and Tropical Meteorology