Severe thunderstorms and the tornadoes they spawn produce significant loss of life and property across the U.S. This research, which will support involvement of the lead investigator and his students in VORTEX2 (the Verification of the Rotation in Tornadoes Experiment, Phase 2) and follow-on analysis of data both previously and yet to be collected, will employ unique mobile X- and W-band Doppler radar measurements describing both tornadic and non-tornadic thunderstorms. Of special interest are polarimetric measurements made in supercells combined with rapid-scan (i.e., rapidly repeated) volumetric radar descriptions of tornadic supercells. The former will provide 3-D descriptions of hydrometeor distributions in these storms, which are necessary for a full understanding of storm thermodynamics and dynamics while the latter will illuminate rapidly evolving and recurrent storm features. Tandem numerical experiments will ingest these measurements into a state-of-the-art cloud model in order to obtain improved estimates of atmospheric variables not directly measured by radar (such as air temperature, moisture content and vertical velocity within storm updrafts/downdrafts). This project will also support collection and analysis of data from the first rapid-scan polarimetric X-band mobile Doppler radar utilized in the study of severe thunderstorms, whose development was previously supported by NSF.
The Intellectual Merit of this work derives from obtaining a more complete understanding of severe thunderstorms, the tornadoes they produce, and detailed dynamical relationships between the two.
Broader Impacts will be immediately realized through training of graduate students involved in data collection and analysis, and through the PI's involvement in undergraduate education and dissemination of result both through formal publications and various media outlets. Ultimately, this work may have societal benefits through improved numerical forecasts and more timely public warnings. Benefits will also accrue through critical evaluation and resulting improvement of cutting-edge mobile radar technologies.
This project furthered our understanding of tornadoes and supercell storms, which spawn the largest and most intense tornadoes. Its goals were met by conducting field experiments in the southern plains each spring, during which the P. I. and his graduate students used a mobile, rapid-scan, polarimetric Doppler radar (RaXPol) to probe tornadoes and potentially tornadic storms. Mobile radars allow one to get close enough to collect high-resolution data safely; polarimetric radars allow one to identify the type of hydrometeors present, which is useful for understanding cloud and precipitation processes and for identifying tornado debris; rapid-scan radars allow one to observe the fast evolution of tornadoes and their parent storms. The graduate students and the P. I. analyzed data we collected during high-profile events such as the Greensburg, Kansas EF-5 tornado on 4 May 2007 and the EF-5 tornado near El Reno, Oklahoma on 24 May 2011. Data were collected also during two major tornadoes near Oklahoma City on 19 May 2013 and during the widest tornado ever documented, near El Reno, Oklahoma on 31 May 2013, among others. In addition, mobile Doppler lidar and mobile, electronically scanning (also rapid scan) radar data collected in supercells during VORTEX2 (2nd Verification of the Origins of Rotation Experiment) were analyzed; valuable insights into tornado evolution were learned and it was determined that a mobile Doppler lidar can complement a mobile radar when there are no hydrometeors present ("clear air") in the vicinity of a tornado. Radar data we collected were also ingested into numerical models to produce a more complete picture of what goes on inside a supercell when it is producing a tornado. During the project, three students supported by this grant earned their Ph. D. One, a woman, has an academic position at a major university in the U. S. (women are underrepresented in the work force in the atmospheric sciences at universities), one worked as a post-doctoral researcher at the National Severe Storms Laboratory and just accepted an academic appointment at another major university in the U. S., and the other is currently a post-doctoral researcher at the National Severe Storms Laboratory. Data collected, with support from this grant, are being analyzed by two new graduate students, both supported by a successor grant. Thus, support from this grant has contributed toward the next generation of researchers and teachers who will try to learn more about severe storms and tornadoes and ultimately save lives. The P. I. wrote and published a new textbook at the university level on severe storms and tornadoes; along with his graduate students, many journal articles based on the research supported by this grant were written, accepted, and published, thus promulgating our research to the wider research and academic communities. Finally, the P. I. appeared on many national and international television and radio programs, and was interviewed by the press, spreading the word about our research, thus making the public better informed about science research going on in this country.
