Estimating Vertical Heat Flux Profiles Using UAS and LIDAR Observations

Diurnal variations in solar heating drive vertical fluxes of heat, moisture, and momentum throughout the depth of the planetary boundary layer (PBL), which has feedback on larger-scale weather systems. Recent advancements in using unmanned aircraft systems (UAS) for collecting atmospheric observations provide a new perspective on characterizing physical processes in the PBL. In particular, studies have shown that it is possible to estimate vertical sensible and latent heat flux distributions by evaluating changes in potential temperature and specific humidity between consecutive vertically-profiling UAS flights. However, this method relies on assumptions of homogeneity and absence of vertical motions that are not always representative of observed PBL flows. This study seeks to improve this method of vertical heat flux estimations with UASs by incorporating measurements of vertical velocities from a Doppler wind lidar (DL).

The University of Oklahoma (OU) CopterSonde is a rotary-wing unmanned aircraft system (rwUAS) designed for high resolution thermodynamic and kinematic measurements of the atmospheric flow. Continuous vertical profiles of temperature, humidity, pressure, and horizontal winds with the CopterSonde were measured at the Kessler Atmospheric and Ecological Field Station (KAEFS) in central Oklahoma on several occasions to study the evolution of the early morning PBL. These profiles, obtained on the order of once every 10-20 minutes, extended to an altitude of 2500 feet above ground level (AGL), and eventually to 5000 feet AGL. KAEFS is additionally outfitted with an Oklahoma Mesonet station, a DL, and eddy covariance flux towers. This presentation will evaluate the utility of combining data from the CopterSonde and DL to estimate vertical heat fluxes, which will be validated against data from the surface flux towers.