The interaction between atmospheric boundary layer structures and a thunderstorm outflow using unmanned aircraft system in situ observations

On 14 August, 2014, a multi-cell cluster of storms created an outflow that swept through the Pawnee National Grassland in north central Colorado. Three unmanned aircraft systems (UAS), two Texas Tech Ka-band radars, and one Doppler on Wheels (DOW) mobile radar were used to sample the planetary boundary layer (PBL) before, during and after the outflow boundary crossed the sensors. Analysis of the data will be done to clarify what impact PBL structures ahead of the outflow boundary have on the structure and wind speed of an outflow. Using UAS as a new way to measure vertical motion, moisture, and temperature makes it more precise and easier to determine the structures of the PBL before and in the outflow. During the passage of the outflow boundary, the three radars maintained time synchronization allowing for multi-Doppler wind synthesis. The UAS flew for 20 minutes during the passage of the outflow boundary at 3 different heights logging data on the environment before and inside the outflow. Vertical wind synthesis using the multi-Doppler lobe coupled with these data from the UAS is used to determine any effects the prior PBL structure has on the structure and wind speed of the outflow boundary. The combination of in-situ, above-ground thermodynamic and kinematic observations collected by the UAS and remote kinematic observations collected by the radars will enable a truly novel examination on how the PBL convective structures affect an airmass boundary.