School of Meteorology

Convection connections: the interplay of dynamics, thermodynamics, and microphysics in supercell thunderstorms

Dr. Daniel Dawson
Research Scientist
Center for Analysis and Prediction of Storms
University of Oklahoma

06 March 2015, 1:00 PM

National Weather Center, Room 5600
120 David L. Boren Blvd.
University of Oklahoma
Norman, OK

During the past few decades, two major developments in meteorology have revolutionized our understanding of supercell thunderstorms: 1) the advent of Doppler and polarimetric weather radar systems capable of observations with high spatial and temporal fidelity, and 2) the development of increasingly powerful computers and numerical modeling techniques capable of simulating the complex dynamics, thermodynamics, and microphysics of these storms on ever more refined grids.
In view of these three physical frameworks, this talk will focus on recent progress in our understanding of the complex behavior of supercells from a numerical simulation perspective, with an emphasis on the microphysical and thermodynamic aspects. In particular, a sufficiently detailed treatment of microphysics within the numerical model will be shown to be crucial to the task of adequately representing both important thermodynamic features (the cold pool and associated outflow boundaries), and dynamical behavior (storm propagation, updraft tilt, and tornadic activity). Additionally, the feedback of the flow field to the microphysical structure primarily through the mechanism of hydrometeor size sorting will be discussed in the context of commonly observed polarimetric radar features in supercells (such as the ZDR arc).
Finally, some implications of these important connections for 1) improved physical understanding of the nature and behavior of super cells and associated tornadoes, 2) improved numerical prediction and warnings of these phenomena (particularly in the context of the “Warn-on-Forecast” effort), and 3) the impacts of microphysics on other convective and non-convective weather and climate phenomena will be briefly discussed as avenues for future research.

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