32nd Conference on Broadcast Meteorology/31st Conference on Radar Meteorology/Fifth Conference on Coastal Atmospheric and Oceanic Prediction and Processes

Monday, 11 August 2003: 11:30 AM
The Kinematic and Thermodynamic Effects of Vorticies Within a Dryline
Michael S. Buban, CIMMS/Univ. of Oklahoma, Norman, OK OK; and C. L. Ziegler and E. N. Rasmussen
Poster PDF (2.2 MB)
During May and June 2002 a massive field project, the International H20 Project (IHOP), was conducted over the southern Great Plains. A main objective of this campaign was to document the 4-dimensional distribution of water vapor and the kinematic and thermodynamic processes specifically relating to convective initiation. During the afternoon of 22 May 2002 the IHOP facilities collected high resolution data from a small region in the eastern Oklahoma panhandle over which a sharpening dryline had become established.

Observations and dual-doppler analyses of this data suggest the presence of well-defined, kilometer-scale vorticies along the dryline. Similar structures have recently been observed along other drylines and the Denver Convergence Zone (DCZ). We hypothesize that these vorticies are associated with local maxima in vertical velocity, specific humidity, virtual potential temperature, and the presence of cumulus. Our second hypothesis is that deep cumulus development requires the mesoscale updraft’s parcels to achieve their Lifted Condensation Level (LCL) and Level of Free Convection (LFC) prior to detraining from the updraft. This latter hypothesis is expressed via dimensionless relations among the horizontal and vertical length and velocity scales, including the LCL and LFC as “vertical moisture” length scales.

In this study, data collected on 22 May 2002 will be analyzed to test the above hypotheses. Analyses from 2- to 4- ground-based Doppler radars will be used to determine the 3-D wind field. The 3-D thermodynamic structure of the boundary will be determined through the analysis of in-situ mobile mesonet surface observations, aircraft traverses, refractivity derived humidity, and mobile soundings. Use of high resolution satellite imagery and digital photogrammetry will permit accurate identification of cumulus locations. Using these analyses, the two hypotheses will be tested through correlations among vorticies, mesoscale updrafts, specific humidity, and virtual potential temperature.

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