Estimation and Evaluation of Atmospheric CT2 using Small Unmanned Aerial Systems

Turbulence can lead to significant spatial and temporal fluctuations in the thermodynamic and kinematic structure of the atmosphere. One method of characterizing these spatial variations is through calculation of the structure function, which is related to the spatial variance of the atmospheric parameter of interest. Moreover, if the turbulence can be assumed to be locally homogeneous, isotropic, and within the inertial subrange of spatial scales, the structure function can be scaled to a theoretical constant known as the structure function parameter. This study presents a method for estimating the temperature structure function parameter, C_T², using thermodynamic measurements collected by a small unmanned aerial system (UAS) configured to trace out a circular flight path over a series of distinct heights within the lower atmospheric boundary layer. The UAS-derived C_T² values collected at the lowest height have been verified against C_T² observations evaluated using data from a 3-D sonic anemometer. The C_T² values obtained are then compared to evaluate the accuracy and reliability of UAS measurements in estimating C_T² under a variety of atmospheric conditions.