On the Use of Rotary-Wing Aircraft to Sample Near-Surface Thermodynamic Fields: Results from Recent Field Campaigns

Abstract

Rotary-wing small unmanned aircraft systems (sUAS) are increasingly being used for sampling thermodynamic and chemical properties of the Earth’s atmospheric boundary layer (ABL) because of their ability to measure at high spatial and temporal resolutions. Therefore, they have the potential to be used for long-term quasi-continuous monitoring of the ABL, which is critical for improving ABL parameterizations and improving numerical weather prediction (NWP) models through data assimilation. Before rotary-wing aircraft can be used for these purposes, however, their performance and the sensors used therein must be adequately characterized. In the present study, we describe recent calibration and validation procedures for thermodynamic sensors used on two rotary-wing aircraft: A DJI S-1000 and MD4-1000. These evaluations indicated a high level of confidence in the on-board measurements. We then used these measurements to characterize the spatiotemporal variability of near-surface (up to 300-m AGL) temperature and moisture fields as a component of two recent field campaigns: The Verification of the Origins of Rotation in Tornadoes Experiment in the Southeast U.S. (VORTEX-SE) in Alabama, and the Land Atmosphere Feedback Experiment (LAFE) in northern Oklahoma.

Evaluating Temperature Measurements of the iMET-XQ, in the Field, under Varying Atmospheric Conditions

“…By providing sources of energy, the atmospheric boundary layer (ABL) plays a major role in the development of many meteorological phenomena, including convective initiation and tornado-genesis [1]. For example, knowledge of the ABL stability and strength of the inversion at the top of the ABL are critical in severe weather prediction [2]. Improved observational coverage of the ABL will (1) provide better input for numerical weather models, (2) contribute to the improvement of ABL parameterizations, and (3) increase the understanding of ABL processes.…”

“…Unfortunately, the current observations of the ABL are inadequate. Towers do not reach high enough [2,3]; 10 m is standard, although towers as high as 300 m exist [4]. Rawinsondes (or weather balloons) only provide a snapshot of the ABL, because they are only typically released twice daily [2].…”

“…Towers do not reach high enough [2,3]; 10 m is standard, although towers as high as 300 m exist [4]. Rawinsondes (or weather balloons) only provide a snapshot of the ABL, because they are only typically released twice daily [2]. Weather balloons also ascend too rapidly through the lowest levels of the ABL [3] and the location of the vertical profiles is dependent on atmospheric conditions [5].…”

“…Furthermore, the sensor package is typically not recoverable for reuse [3]. Surface-based remote sensing instruments, like microwave radiometers, wind profilers, and sodars, provide vertical profiles at a single point and, therefore, do not provide good horizontal resolution [2]. The same applies to tethered balloons.…”

A Near-Field Gaussian Plume Inversion Flux Quantification Method, Applied to Unmanned Aerial Vehicle Sampling

“…[62] tested 23 different UAVs with a variety of atmospheric sensors designed to measure pressure, temperature, humidity and winds, by comparing UAV measurements to measurements made from a stationary tower on the ground. Lee et al [63] calibrated a meteorological sensor (sampling at 1 Hz) on board two multi-rotor UAV platforms to characterise variability in moisture and temperature up to a height of 300 m. Alaoui-Sosse et al [64] tested a 3.5 kg fixed-wing UAV (including payload) which made use of a fast inertial measurement unit to measure turbulence in the boundary layer. The platform was successfully tested by comparing UAV turbulence measurements to measurements from a stationary tower at a fixed height of 60 m at 10 Hz [64].…”