This research project seeks to further our basic physical understanding of severe convective storms and tornadoes, with an emphasis on tornadoes produced by supercells. The overall goal will be accomplished through the analysis of data collected by state-of-the-art mobile Doppler radars and a mobile Doppler lidar (TWOLF: Truck-Mounted Wind Observing Lidar Facility). The former include: 1) a rapid-scan (mechanically scanning), polarimetric, X-band radar (RaXPol); 2) a rapid-scan, phasedarray, X-band radar (MWR-05XP); and 3) a high-resolution, W-band radar (University of Massachusetts-Amherst's W-band radar).
Some of the radar data to be analyzed includes datasets collected during VORTEX2 (The 2nd Verification of the Origin of Rotation in Tornadoes Experiment) in the springs of 2009 and 2010. The remainder of the radar data to be analyzed include RaXPol and MWR-05XP data collected a during a small, local, field program during the spring of 2011, RaXPol data collected during the spring of 2012, RaXPol and TWOLF/MWR 05XP data collected during the spring of 2013, and RaXPol data collected during the springs of 2014 and 2015.
Intellectual Merit: Using the rapid-scan radars, the evolution of vortex signatures in time and space will be explored in both supercells that produce tornadoes and those that do not. This information can be used to help assess the mechanism(s) of tornado formation. The polarimetric radar will be used to infer information about microphysical processes within supercells and how they might relate to storm structure and evolution, and tornado formation. The high-resolution W-band radar data already collected during VORTEX2 will be further analyzed to document the fine-scale structure of tornadoes and tornado-like vortices. TWOLF will be used mainly to measure the vertical variation in winds in and near tornadoes and mesocyclones in the lowest 100 m, an undertaking, owing to ground clutter contamination, that is difficult with radars and is extremely challenging by in-situ probing. Very little is known about the boundary layer in tornadoes or under storms when they form. The character of the boundary layer is thought to be a very important factor in determining the potential intensity of intense vortices such as tornadoes.
Broader Impacts: It is anticipated that forecasts and warnings of tornadoes and other severe weather phenomena such as large hail and straight-line winds will be improved with an increase in a physical understanding of them. The results from this project may be useful to the National Weather Service and private forecasting companies, and could help mitigate property damage and save lives. Graduate students will be trained and become part of the pool of the next-generation of researchers.
