Vertical Sampling Scales for Atmospheric Boundary Layer Measurements from Small Unmanned Aircraft Systems (sUAS)

Abstract

Abstract:The lowest portion of the Earth's atmosphere, known as the atmospheric boundary layer (ABL), plays an important role in the formation of weather events. Simple meteorological measurements collected from within the ABL, such as temperature, pressure, humidity, and wind velocity, are key to understanding the exchange of energy within this region, but conventional surveillance techniques such as towers, radar, weather balloons, and satellites do not provide adequate spatial and/or temporal coverage for monitoring weather events. Small unmanned aircraft, or aerial, systems (sUAS) provide a versatile, dynamic platform for atmospheric sensing that can provide higher spatio-temporal sampling frequencies than available through most satellite sensing methods. They are also able to sense portions of the atmosphere that cannot be measured from ground-based radar, weather stations, or weather balloons and have the potential to fill gaps in atmospheric sampling. However, research on the vertical sampling scales for collecting atmospheric measurements from sUAS and the variabilities of these scales across atmospheric phenomena (e.g., temperature and humidity) is needed. The objective of this study is to use variogram analysis, a common geostatistical technique, to determine optimal spatial sampling scales for two atmospheric variables (temperature and relative humidity) captured from sUAS. Results show that vertical sampling scales of approximately 3 m for temperature and 1.5-2 m for relative humidity were sufficient to capture the spatial structure of these phenomena under the conditions tested. Future work is needed to model these scales across the entire ABL as well as under variable conditions.

New Setup of the UAS ALADINA for Measuring Boundary Layer Properties, Atmospheric Particles and Solar Radiation

“…The smallest systems with a weight below or slightly exceeding 5 kg are mainly equipped with basic meteorological sensors for measuring humidity and temperature [3]. They can be used comparable to a recoverable radiosonde [4], but have the advantage of performing specific flight patterns, as demonstrated by Hemingway et al [5], which shows the repeated sampling and analysis of the small-scale atmospheric boundary layer (ABL) phenomena with a multicopter system. Some systems provide measurements of additional parameters, e.g., ozone concentration [6] or the concentration of the greenhouse gases methane and carbon dioxide [7].…”

Considerations for Atmospheric Measurements with Small Unmanned Aircraft Systems

“…Variogram analysis has shown to provide insight into the distance over which spatial autocorrelation dissipates and coherence vanishes, providing a measure of the optimal spatial separation between measurements and observations of horizontal inhomogeneities. Results suggest that the multiple scale domains present in the ABL can be resolved using sUAS [19].…”

“…Due to observed variations, questions may arise as the accuracy or "truth" of the data when compared to each other. While this has not been fully addressed by this study, data comparisons have been provided elsewhere in a first attempt to address this concern [19]. …”

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

“…The UAV could also be used as a mobile data transmission base station [55]. Hemingway et al [65] used a variogram analysis of temperature and humidity measurements, derived from a 1.2 kg UAV flying within the atmospheric boundary layer, to observe meteorological phenomena of a sub-kilometre spatial scale. Zhou et al [66] made in-situ measurements of aerosol concentrations from on-board a small UAV in Nanjing, China during an air pollution episode.…”