One of the main challenges in the boundary-layer turbulence research consists in advancing turbulence theory towards describing turbulent regimes over inhomogeneous and irregular surface which is often the case in nature. Novel observational techniques are required to sample turbulence statistics in such conditions. To that aim, a light-weight payload for atmospheric turbulence measurements is designed and used on a vertical take-off and landing (VTOL) fixed-wing unmanned aerial vehicle (UAV). Such an observational platform complements traditional mast observations and makes it possible to sample turbulence statistics over remote and inhomogeneous landscapes. The advantages of the VTOL scheme consist in: i) minimizing the risk of the payload damage during landing; ii) less strict requirements to the surface conditions in the landing area. The turbulence payload consists of a miniature seven-hole probe, inertial navigation system and a fine-wire resistance thermometer. The seven-hole probe and the fine-wire temperature sensor were designed and calibrated as part of this study. In addition, the payload also includes a slow-response temperature-humidity sensor, relatively fast humidity sensor as well as an infrared surface temperature sensor. For the onboard data-logging, a computer based on Raspberry Pi 4 is used. The whole system has been successfully tested at the Tsimlyansk research station, Russia.

A fixed-wing unmanned aerial vehicle “Tsimlyanin” having a hybrid vertical take-off and landing (VTOL) scheme with a compact meteorological payload is designed for an application to the atmospheric boundary layer (ABL) studies. The main purpose of such an observational platform is to supplement traditional mast observations by sampling horizontal and vertical inhomogeneities of mean variables and turbulent statistics. Such observations are needed to advance turbulence theory especially for the ABL over inhomogeneous landscapes and also in non-stationary conditions. The VTOL scheme is chosen as it provides a safer take-off and landing and is less demanding to the landing conditions. The designed turbulence payload consists of a seven-hole probe, inertial navigation system and a fast-response platinum-wire temperature sensor. It is complemented with the static pressure sensor, a slow-response temperature and humidity sensor and an infrared surface temperature sensor. The data acquisition and logging is performed by an on-board computer. The designed system has been successfully tested in the summer campaign in 2020 in Tsimlyansk, Russia.