The Principal Investigators (PIs) will conduct a multi-institution, integrated study encompassing several core science foci of the second Verification of the Origin of Rotation in Tornadoes Experiment (VORTEX2) to be held in 2009. In support of this research, and in support of the overall VORTEX2 program, the PIs will field several core VORTEX2 instrumentation systems. The field-project and analysis effort will permit the coordinated collection of multi-platform measurements and their integrated analysis. The diverse data sets will result from fixed and mobile radars, mobile mesonets, and in situ instrumentation with the goal of developing a more comprehensive scientific understanding of the genesis, maintenance, and structure of tornadoes and supercells and their relationship to the environment. This study will combine integrated analyses with those of less comprehensive data from over 130 tornadoes obtained during the Radar Observations of Thunderstorms And Tornadoes Experiment (ROTATE) program (1996-2007).
Scientific Motivation and Intellectual Merit: Current level of understanding in several areas of tornado science fails to provide answers to fundamental questions including the true range of sizes, intensities, and structures of tornadoes. The factors governing the occurrence and timing of tornado genesis, growth, intensification, maintenance, and dissipation, as well as the modes of genesis, are hypothesized from previous work, but remain largely unvalidated observationally, as do details concerning vertical wind field profiles, and the evolution and structure of damaging winds near the ground. The specific role of downdrafts in tornadogenesis and the sensitivity of the tornadogenesis process to microphysical and thermodynamic characteristics are not known. Thus, while significant advances have been made in addressing many of these questions using data from the original VORTEX and from ROTATE; these results have been limited. Specifically, VORTEX2 will provide an integration of multiple-Doppler mobile radar data with comprehensive in situ thermodynamic data that has not been achieved previously.
Broader Impacts: Improved understanding of tornado genesis, maintenance, structure, and environmental dependencies will have a broad impact on the ability to detect, warn, and forecast these severe events and to reduce subsequent casualties. The fielding of mobile Doppler radars, mobile mesonets, and in situ thermodynamic probes will be led by the PIs. These datasets will be available to the scientific community for both scientific and educational purposes and are likely to be extensively used by a large number of investigators and educators.
Normal 0 false false false EN-US X-NONE X-NONE - How, when, and why do tornadoes form? Why some are violent and long lasting while others are weak and short lived? - What is the structure of tornadoes? How strong are the winds near the ground? How exactly do they do damage? - How can we learn to forecast tornadoes better? Current warnings have an only 13 minute average lead timeand a 70% false alarm rate. Can we make warnings more accurate? Can we warn 30, 45, 60 minutes ahead? ----------------------------------------------------------------------------- VORTEX2 was conceived to answer these questions. ----------------------------------------------------------------------------- VORTEX2 was the largest and most ambitious tornado study ever. The research supported by this NSF grant enabled the study of several tornadic storms. In one, a triggering mechanism, a "secondary surge" was shown to be well correlated with the formation, initial weakening, then re-intensification of the tornado, suggesting that it may have triggered tornadogenesis. The could lead to improved forecasts. Rare observations inside a tornado were combined with rapid-scan DOW radar observations to reveal the 3D wind structure of a tornado for the first time, including a strong near-surface inflow, central updraft at the surface, meeting a penetrating downdraft from aloft. Also, for the first time, real-time video of damage was compared to direct wind measurements and radar measurements in order to understand what wind speeds and directions caused the damage. If we can understand tornadogenesis better, we can make better predictions. Better predictions mean better warnings, and more time for people to seek safety. The intellectual merit of VORTEX2 adn this grant was and continues to be realized through the publication of peer reviewed papers describing supercell evolution, triggers for tornadogenesis, low level tornado wnid structure, and related topics. Several papers are either already published in technical journals, in review, or in final preparation. These papers cover a wide variety of subjects related to supercells and tornadoes and represent a major advance for the field. The broader impact of VORTEX2 and this grant is being realized through a better understanding of tornadogenesis, which will likely lead to better tornado predictions and warnings. For example, a triggering mechanism for tornadogenesis was described in one paper. If this proves to be a general result, detection of this mechanism may result in more accurate, more refined tornado warnings. Two papers describe how low level rotation is generated, preceding tornadogenesis, the understanding of which may lead to better predictions and warnings. Two other papers describe the wind field structure of tornadoes in the lowest levels, from 3-30 m AGL, revealing that the winds at the lowest levels are comparably strong to those observed aloft by radar, the impact being that winds experienced by structures near the ground may be stronger than otherwise thought, possibly impacting construction standards.
