| Popis: |
This study investigates the use of a balloon-launched small Uncrewed Aircraft System (sUAS) for the measurement of turbulence in the troposphere and lower stratosphere. The sUAS was a glider which could conduct an automated descent following a designated flight trajectory and equipped with in-situ sensors for measuring thermodyanamic and kinematic atmospheric properties typically measured using balloon-borne instruments. The trajectory of the glider allowed for improved statistical convergence and higher spatial resolution of derived statistics measured by the in-situ sensors. In addition, this aircraft was equipped with an infrasonic microphone to assess its suitability for the remote detection of clear-air turbulence. The capabilities of the sUAS and sensing systems were tested using three flights conducted in 2021 in New Mexico. It was found that the profiles of temperature, humidity and horizontal winds measured during descent were consistent with those made by radiosonde. Importantly, analysis of the statistics produced along the flight trajectory allowed the identification of key turbulence quantities and features such as gravity waves, thermals and tropopause folding, which allowed the connection to be made between the locations of increased turbulence intensity and the source of its generation. In addition, the infrasonic microphone amplitude was found to be correlated with the measurements of turbulence intensity, indicating that the microphone was sensing turbulence. However, interpretation of the microphone signal was convoluted by the altitude dependence of the microphone response and the difficulty in discriminating individual sources from within the microphone signal. |
