AGS-PRF: Improved In Situ Thermodynamic Sampling of Severe Storms with Unmanned Aircraft Systems Through Improved Wind Estimation and Energy Harvesting

Elston Jack S, Boulder CO

Investigators

Abstract

Advancement of research into the origins of tornadoes in supercell thunderstorms is heavily dependent upon the ability to accurately measure the in-situ thermodynamic properties within supercells. A pilot program during the VORTEX2 project proved the ability to conduct directed sampling using small unmanned aircraft systems (UAS), achieving the first ever sampling of the rear flank gust front and airmass associated with the rear flank downdraft of a supercell thunderstorm by a UAS. Despite this success, much work remains before such a system will be able to regularly return scientifically valuable and sufficiently accurate measurements over the volume and time span needed. This work will provide the next step needed for effective in-situ sampling of severe storms. An investigation into the techniques for sampling storm features will be performed, including improved wind estimation and the use of wind energy harvesting to extend unmanned aircraft sampling missions. The product of this fellowship will be combined with current efforts at the University of Colorado Boulder and University of Nebraska-Lincoln to construct a next generation UAS for meteorological sampling. These combined efforts will transform severe storms research by providing a deployable instrument system for "routine" access into these storms with small, inexpensive aircraft capable of targeted sampling of the thermodynamic properties of complex atmospheric phenomena. Intellectual Merit The new capabilities for targeted in-situ measurements in complex atmospheric phenomena are potentially revolutionary. Contributions include: 1. Characterization of current methods for wind velocity and acceleration estimation, with respect to the accuracy of currently available sensors for small unmanned aircraft systems. 2. Development of a hybrid wind state estimator to fuse on-board sensor measurements from those obtained through the synthesis of Doppler radar observations. 3. Estimation of the amount of energy that can be extracted from severe storms employing algorithms for static soaring, dynamic soaring, and energy extraction from gusts. 4. Construction of a hybrid controller to take advantage of the energy available in severe storms to either follow a specific sampling pattern, or extend mission endurance through loitering. Broader Impacts This research spans two distinct disciplines, and requires the collaboration of three different institutions. It will provide a critical component for the next-generation system designed to accurately measure the thermodynamic properties of severe storms. These measurements will benefit both modeling and forecasting, allowing for greater understanding of the storms, and better prediction systems which will ultimately save lives.