Monday, 7 January 2013
Exhibit Hall 3 (Austin Convention Center)
Predicting convective initiation (CI) along the dryline has long proven difficult for operational meteorologists, and the quintessential method of improving such predictions is to advance fundamental understanding of the finescale dryline structure and processesincluding those of dryline-imbedded vortices. Although these vortices, or misocyclones, are known to vary in size and propagate along dryline boundaries, only recently has radar technology improved enough to make observations in a detailed manner. Thus, little is known about their formation and evolution. They are theorized to be caused by the intersection and tilting of convective rolls along various air mass boundaries [Buban et al. 2007], and may be regions of enhanced vertical air motionpotentially catalyzing CI. If rolls are indeed responsible for these misocyclones, the size and spacing of misocyclones may be directly related to boundary layer depth. Likewise, vertical shear would be necessary for the roll, and consequently, vortex formation. The need, if any, for cross-dryline shear will also be assessed. Using dual-Doppler methodology and data from two Texas Tech Ka band (TTUKa) radars with 0.49 deg beam width, multiple dryline events are objectively analyzed to derive 2-D wind fields and regions of enhanced convergence and vorticity. RHIs are also utilized to record the vertical wind profile and shape of the dry front. The findings of a highly complex dryline structure, the necessity of dryline-intersecting linear structures for the existence of misocyclones, and other findings of interest will be discussed in this presentation.
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