Doppler Weather Radar Research and Development
NSSL Project 5 – Investigation of the Use of Dual-Polarization Radar to Improve Quantitative Precipitation Estimation for Improving Flash Flood and Flood Detection, Warnings, and Forecasts:
Investigation of Microphysical Processes in Clouds and Precipitation Using Polarimetric Radar Measurements
Funding Type: CIMMS Task II
Objectives
Investigate polarimetric signatures in tornadic and nontornadic supercell
storms for better understanding microphysical aspects of tornadogenesis.
Accomplishments
Detailed analysis of polarimetric data from nine tornadic and six nontornadic
supercell storms has been performed. It reveals a number of distinctive
and repetitive polarimetric signatures attributed to different microphysical
processes and features in the storms. These signatures are associated
with tornadic debris, hail, vertical motions, updraft rotation, and
size sorting due to vertical veering of the wind. Especially notable
are polarimetric designations of tornadic debris and storm relative
helicity (SREH). The latter one is linked to the “arc ZDR” signature,
that is, arc-shaped area of differential reflectivity enhancement at
the southern edge of the forward-flank downdraft. This signature may
serve as a precursor of intense rotation in the storm and indicator
of its potential severity.
This project is ongoing.
Publications
Cao, Q., G. Zhang, E. Brandes, T. Schuur, A. Ryzhkov, and K. Ikeda, 2007:
Analysis of video disdrometer and polarimetric radar data to characterize
rain microphysics in Oklahoma. J. Appl. Meteor., submitted.
Examples of arc ZDR signatures in five supercell storms observed in Oklahoma. Contours of Z are overlaid.