Abstract
Supercell thunderstorms can form extremely dangerous and destructive tornadoes. While high fidelity supercell simulations have increased the understanding of supercell mechanics to help determine how and when tornadoes form, there is a lack of targeted, in situ measurements taken aboveground in supercells to validate these simulations. Pseudo-Lagrangian drifters (PLDs) are atmospheric probes that can be used to attain thermodynamic measurements in areas that are difficult or dangerous to access, such as from within supercells. Of particular interest in understanding tornadogenesis is the rear-flank downdraft (RFD). However, strong outflow winds behind the rear-flank gust front (RFGF) make the RFD particularly difficult to access with balloon-borne sensors launched from the ground. A specific type of PLD, an air-launched drifter (ALD) that is released from unmanned aircraft systems (UAS), can be used to access RFD inflows, present at higher altitudes. Results from initial tests of ALDs are shown, along with results from a ground-released PLD test during a supercell intercept in the Oklahoma Panhandle on 12 June 2018. In characterization tests performed at the 2018 International Society for Atmospheric Research using Remotely piloted Aircraft (ISARRA) flight week, it was found that the ALD sensor system performs reasonably well against industry standards. However, improvements will be made to increase the aspiration of the sensor.
Highlights
Tornadoes are one of the most common and destructive forms of extreme weather in the UnitedStates
To assess the feasibility of deploying air-launched drifter (ALD) from an small UAS (sUAS) to be entrained into the rear-flank downdraft (RFD), simulations of possible ALD trajectories were performed
A high-resolution supercell simulation [16] was created using Cloud Model 1 (CM1), a three-dimensional, non-hydrostatic, non-linear, time-dependent, numerical atmospheric model developed at the National Center for Atmospheric Research (NCAR)
Summary
Tornadoes are one of the most common and destructive forms of extreme weather in the United. A better understanding of supercell tornadoes can help inform future research and increase tornado warning lead time Remote sensing systems such as weather radar do not provide thermodynamic data in the RFD. Facilitating the development of UAS has been a high priority in both the meteorological and engineering fields, in part driven by the advantages UAS pose in collecting aboveground in situ measurements from within supercells Due to these technological advances, small UAS (sUAS) have been able to get closer to critical parts of the storm than ever before. Atmospheric pseudo-Lagrangian drifters (PLDs) took the form of large, helium-filled, superpressure balloons that functioned as high-altitude observation platforms [8]. Outflows following the RFD gust front make ground-release of PLDs impractical as balloons will be carried away from the storm. Air-launched drifters (ALDs) are a specific type of atmospheric PLD that are released from UAS
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