Wind and turbulence estimation in the surface layer using commercial-off-the-shelf quadcopters

The use of multirotor Uncrewed Aerial Systems (UAS) platforms for wind measurements in the lower atmosphere has become increasingly popular over the last decade. The most common methods include the use of flight controller data (“indirect method”) and the use of a sonic anemometer mounted above the multirotor frame (“direct method”). While progress has been made to accurately estimate winds over averaging periods of a few seconds or more using these methods, the feasibility and accuracy of turbulence measurements remain largely unexplored. Furthermore, applying the currently used methodologies requires the need for building custom-made vehicles and/or constructing vehicle dynamics models using wind tunnels and other specialized technical equipment and software. In this contribution, we aim to explore the ability of hovering low-cost commercial off-the-shelf (COTS) quadcopters to measure turbulence quantities, including variances and turbulence kinetic energy (TKE), using the indirect method. The approach is innovative because it only relies on the use of easily retrievable data from COTS multirotor UAS. There is no need for custom-built vehicles, system identification of a dynamic vehicle model, or tuning of flight control parameters, making the approach cost-efficient and easily accessible to atmospheric scientists without an engineering and/or technical background. For an initial investigation, flights were performed next to a sonic anemometer at 10 m above ground using a COTS quadcopter (DJI Mavic) and with a custom-built quadcopter using an open-source flight controller. Initial results show that the estimated horizontal and vertical wind variances, as well as the TKE compare well between the different quadcopters and the sonic anemometer measurements. More systematic field tests are planned, including the use of differently configured COTS and custom-built quadcopters, which will enable an investigation of the impact of disc loading on the resolution of the retrieved turbulence scales. Results of these investigations will be reported at the conference.