The main objective of this grant was to further our basic physical understanding of severe convective storms and tornadoes produced by supercells. To accomplish this task, my graduate students and I, supported by this grant, conducted field programs in the springs of 2013, 2014, 2015, and 2016, during which detailed datasets were collected in the Plains of the U. S. for tornadoes and their parent storms using a mobile, rapid-scan, polarimetric Doppler radar and, during 2015 only, using a mobile Doppler lidar. The significance of the former is that the wind and precipitation fields and the nature of the precipitation were measured at short time intervals commensurate with the rapid formation and evolution typical of tornadoes. The significance of the latter is that fine-scale profiles of the wind near the ground near tornadoes could be obtained, something that has hitherto not been attempted and is very difficult or impossible to do with radars. Data collected during these field experiments and data collected during VORTEX-2 (the second Verification of the Origin of Tornadoes Experiment), in 2009 and 2010, were analyzed. In particular, the evolution and structure of tornadoes were documented for a major outbreak near El Reno, Oklahoma on 31 May 2013 and for a number of other tornadoes. It was found that tornadoes in some supercells begin near the surface after a mesocyclone (a cyclone around 2 – 5 km across) about 1 – 2 km above the ground forms. It was also found that very high wind speeds can occur in tornadoes just above the ground (as high as 300 m s^-1 or greater), but may not be evident without Doppler-radar documentation when the surface does not contain any structures that can be damaged, such as an open field. Also, the structure and motion of multiple vortices within a tornadoe were analyzed in unprecedented detail; it was found that the individual vortices begin and end in preferred quadrants of their parent circulation. Anticyclonic tornadoes, which are relatively rare, were also documented and analyzed. Several of the graduate students who were at least in part funded by this grant have earned Ph. D. and/or M. S. degrees in meteorology and have gone to teach at other universities, one has gone on to work as a forecaster for the National Weather Service, and another completed his M. S. thesis research and is currently working on his Ph. D. One of the students was a woman; women are underrepresented in meteorology. In summary, there were important scientific findings regarding tornadoes and their parent storms, which will improve our ability to forecast them and their effects; members of the next generation of researchers, educators, and forecasters have been trained. Our research was highlighted in the media nationally and internationally, thus giving the public a look at how science progresses and possibly inspiring young students to consider becoming meteorologists, Finally, a new mobile radar and lidar were tested in the field and used to further our knowledge of tornadoes.

Last Modified: 07/06/2017
Modified by: Howard B Bluestein