Collaborative Research: Study of the Genesis, Evolution, Structure, and Dynamic Climatology of Tornadoes and Their Environments

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Current level of understanding in several areas of tornado science fails to provide answers to some fundamental questions. Basic answers concerning the true distribution of sizes, intensities, or structures of tornadoes are elusive. The influence of the local environment on tornado intensity, the determining factors for the occurrence and timing of genesis, growth, intensification, and dissipation, as well as the modes of genesis are largely unknown, as are details concerning vertical wind field structure, the evolution and structure of damaging winds near the ground, and sub-tornado-scale vortices. Many of these questions are not new; however, due to the current availability of high quality, high-resolution data sets, it is possible to address these questions in a more rigorous manner. The Doppler On Wheels (DOW) mobile radars have collected detailed data sets of several tornadoes in recent years. These data sets represent a treasure trove of unique and valuable information, the analysis of which can be applied to advance understanding of a broad range of fundamental processes related to tornadoes. Data collected using the DOWs during 1995-2003 in the Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX) and the Radar Observations of Tornadoes and Thunderstorms Experiment (ROTATE) will be analyzed, some in conjunction with other radar and in situ observations, to study the genesis, evolution, structure, and climatology of tornadoes and their environments. The VORTEX and ROTATE field campaigns yielded data with unprecedented quality. Through careful radar deployments at ranges of 0.17-15 km from tornado centers, data were obtained at very fine resolution, with cross and along beam data spacing of from 3 - 250 m and 12-75 m, respectively. These observations were obtained during various stages of tornado evolution for 60 tornadoes, providing a broad sample for statistical and climatological analysis. Fast scanning capabilities and carefully selected volume coverage patterns over the depth of interest allowed for temporal resolutions from 13 s in two dimensions, 20 s in limited three dimensional, to 50 s in deep three dimensional volumes. Using carefully designed scanning strategies, deployments capturing tornadogenesis were achieved in several instances, including one with dual-Doppler, in addition to several dual-Doppler deployments on pre-existing tornadoes. Different data sets will be used to explore specific aspects of the phenomena. Detailed dual-Doppler and single-Doppler analyses will be conducted on particular cases in order to evaluate conceptual, numerical, and laboratory models of tornado structure, evolution, and genesis. An analysis of the broad range of tornado data sets will be undertaken in order to develop a climatology of basic tornado structures and dynamics. Single-Doppler retrievals will be conducted on high-resolution volumetric data sets in large tornadoes. DOW radar and other data will be used to study the evolution and structure of tornadoes in varying environments, and their effect on those environments. A greater understanding of tornadogenesis, structure, environmental dependencies, climatology, and other issues described above will have a broad impact on the ability to detect, warn, and forecast these severe events and reduce subsequent casualties.