7A.2 Spatiotemporal Variability of ZDR Column Areal and Altitudinal Extent in Tornadic and Nontornadic Supercells

Monday, 28 August 2017: 4:15 PM
Vevey (Swissotel Chicago)
Adrianne J. Engel, Univ. of Nebraska, Lincoln, NE; and M. S. Van Den Broeke

Handout (8.3 MB)

Differential reflectivity (ZDR) is a polarimetric radar variable used to estimate the mean shape of scatterers to allow for inference of microphysical distributions in supercell thunderstorms. This provides a means for enhanced understanding of the processes occurring throughout supercell life cycles. Past research has noted that ZDR columns – areas of high values associated with strong updrafts that result from the lofting of liquid drops above the environmental 0˚C level – can be used as a proxy for updraft strength. Column altitudinal extent increases as an updraft intensifies, and results from a few studies show correlation between updraft broadness, evidenced by column areal extent, and updraft intensity. Assessing spatial and temporal patterns of ZDR column altitudinal and areal extent above the ambient 0˚C level may offer fundamental information concerning changes in updraft, and consequently, mesocyclone strength. Additionally, maximum column altitude and areal extent can be influenced by environmental variability. Results from analysis of a sample of ~130 supercells in tornadic and nontornadic environments from February 2012 – December 2014 will be discussed to emphasize variability of ZDR column areal and maximum altitudinal extent above the environmental 0˚C level. The degrees to which column maximum altitudinal extent and areal extent vary as a function of convective environment, supercell type (tornadic or nontornadic), and tornado intensity will be underscored.
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