Design and field campaign validation of a multi-rotor unmanned aerial vehicle and optical particle counter

Abstract

Abstract. Small unmanned aircraft (SUA) have the potential to be used as platforms for the measurement of atmospheric particulates. The use of an SUA platform for these measurements provides benefits such as high manoeuvrability, reusability, and low cost when compared with traditional techniques. However, the complex aerodynamics of an SUA – particularly for multi-rotor airframes – pose difficulties for accurate and representative sampling of particulates. The use of a miniaturised, lightweight optical particle instrument also presents reliability problems since most optical components in a lightweight system (for example laser diodes, plastic optics, and photodiodes) are less stable than their larger, heavier, and more expensive equivalents (temperature-regulated lasers, glass optics, and photomultiplier tubes). The work presented here relies on computational fluid dynamics with Lagrangian particle tracking (CFD–LPT) simulations to influence the design of a bespoke meteorological sampling system: the UH-AeroSAM. This consists of a custom-built airframe, designed to reduce sampling artefacts due to the propellers, and a purpose-built open-path optical particle counter (OPC) – the Ruggedised Cloud and Aerosol Sounding System (RCASS). OPC size distribution measurements from the UH-AeroSAM are compared with the cloud, aerosol, and precipitation spectrometer (CAPS) for measurements of stratus clouds during the Pallas Cloud Experiment (PaCE) in 2019. Good agreement is demonstrated between the two instruments. The integrated dN∕dlog (Dp) is shown to have a coefficient of determination of 0.8 and a regression slope of 0.9 when plotted 1:1.

In-situ microphysical characterization of low-level clouds in the Finnish sub-Arctic, extensive dataset

“…In 2012, 2013 and 2015 both instruments were installed and used during PaCE (Doulgeris et al, 2020). In 2017 and 2019, only CAPS was used (Girdwood et al, 2020). An overview of each year's campaign duration and the cloud spectrometer ground setups' availability is presented in figure 2.…”

“…Heymsfield et al, 2011;Craig et al, 2014;Petäjä et al, 2016) and recently, by Unmanned Aerial Systems (UASs) (e.g. Girdwood et al, 2020;Brus et al, 2021;Harrison et al, 2021); in-situ sampling by using laboratory cloud chambers (e.g. Möhler et al, 2003;Stratmann et al, 2004;Nichman et al, 2017;Doulgeris et al, 2018) and in-situ ground based measurements (e.g.…”

Measurement report: Properties of aerosol and gases in the vertical profile during the LAPSE-RATE campaign

“…The mixing height of the atmospheric boundary layer and wind speed and direction are influenced by a number of factors, including the amount of solar and surface stored energy and terrain inhomogeneity (Carbone et al, 2010). The atmospheric boundary layer can be investigated through various means, including balloon-borne soundings, tethersondes, dropsondes and hot-air balloons (e.g., Laakso et al, 2007;Greenberg et al, 2009;Nygård et al, 2017); towers (e.g., Heintzenberg et al, 2011;Andreae et al, 2015); remote sensors, including ceilometers, sodars, Doppler lidars and radar techniques (e.g., O'Connor et al, 2010;Schween et al, 2014;Vakkari et al, 2015); and conventional research aircrafts (Hermann et al, 2003;Twohy et al, 2002;Benson et al, 2008). Unmanned aerial systems (UASs) have recently gained popularity as measurement platforms in atmospheric research.…”

Measurement report: Balloon-borne in situ profiling of Saharan dust over Cyprus with the UCASS optical particle counter

“…Recently, the focus of such activities has extended towards the eastern Mediterranean as this region is on the crossroad of aerosol transport of mineral dust from Sahara and Middle East, continental outflow from Europe, and biomass-burning smoke from eastern Europe and central Asia (Georgoulias et al, 2016). The majority of dust storms over the eastern Mediterranean basin occur between December and April with maximum dust load during April (Israelevich et al, 2002). The main zones of cyclogenesis in the Mediterranean Sea determine dust uplift and transport in the region (Alpert et al, 1990;Bou Karam et al, 2010).…”