The Small Whiskbroom Imager for atmospheric compositioN monitorinG (SWING) and its operations from an unmanned aerial vehicle (UAV) during the AROMAT campaign

Abstract

Abstract. The Small Whiskbroom Imager for atmospheric compositioN monitorinG (SWING) is a compact remote sensing instrument dedicated to mapping trace gases from an unmanned aerial vehicle (UAV). SWING is based on a compact visible spectrometer and a scanning mirror to collect scattered sunlight. Its weight, size, and power consumption are respectively 920 g, 27 cm × 12 cm × 8 cm, and 6 W. SWING was developed in parallel with a 2.5 m flying-wing UAV. This unmanned aircraft is electrically powered, has a typical airspeed of 100 km h −1 , and can operate at a maximum altitude of 3 km.We present SWING-UAV experiments performed in Romania on 11 September 2014 during the Airborne ROmanian Measurements of Aerosols and Trace gases (ARO-MAT) campaign, which was dedicated to test newly developed instruments in the context of air quality satellite validation. The UAV was operated up to 700 m above ground, in the vicinity of the large power plant of Turceni (44.67 • N, 23.41 • E; 116 m a.s.l.). These SWING-UAV flights were coincident with another airborne experiment using the Airborne imaging differential optical absorption spectroscopy (DOAS) instrument for Measurements of Atmospheric Pollution (AirMAP), and with ground-based DOAS, lidar, and balloon-borne in situ observations.The spectra recorded during the SWING-UAV flights are analysed with the DOAS technique. This analysis reveals NO 2 differential slant column densities (DSCDs) up to 13 ± 0.6 × 10 16 molec cm −2 . These NO 2 DSCDs are converted to vertical column densities (VCDs) by estimating air mass factors. The resulting NO 2 VCDs are up to 4.7 ± 0.4 × 10 16 molec cm −2 . The water vapour DSCD measurements, up to 8 ± 0.15 × 10 22 molec cm −2 , are used to estimate a volume mixing ratio of water vapour in the boundary layer of 0.013 ± 0.002 mol mol −1 . These geophysical quantities are validated with the coincident measurements.

Observations of Atmospheric NO2 Using a New Low-Cost MAX-DOAS System

“…A mobile DOAS technique implemented as car-DOAS observations can be used for highresolution horizontal observations of tropospheric NO2 and other trace gases. Car-DOAS observations have been used for quantification of total emissions from urban or industrial emission sources [25,26], comparisons with satellite observations [27][28][29], validation of airborne DOAS measurements [30,31] and for comparisons with model simulations [29,32]. Also, car-DOAS measurements have recently been used for comparison with in situ measurements [33].…”

The Airborne ROmanian Measurements of Aerosols and Trace gases (AROMAT) campaigns

“…When observed with the Mobile-DOAS, the plume shows higher NO 2 VCDs and appears narrower than with the airborne instruments. This is partly related to air mass factor uncertainties, but probably also to 3-D effects as the plume is very thin and heterogeneous close the power plants, as discussed in Merlaud et al (2018). Figure 11 shows those AROMAT-1 NO 2 sonde measurements above Turceni which detected the plume.…”

“…Regarding uncertainties on the references AMFs, the added value of knowing the aerosol and NO 2 profile appears when comparing the AMF error budget for airborne measurements above Bucharest (26%, Meier et al 2017) and above the Turceni power plant (10%, Merlaud et al (2018)). In the latter case, there was accurate information on the local NO 2 and aerosol profiles thanks to the lidar and the balloon-borne NO 2 sonde, respectively.…”

"Overview of NO2 pollution level in the lower Danube basin during DANS measurements campaign "

“…This method has been used in several specialty studies in different countriesin order to assess the air quality and pollution level on global, regional and local areas.The DOAS technique can be usedfor staticobservations in zenith geometry in order to assess the content of trace gases in vertical atmospheric columns; also,the DOAS instrument can be mounted on different mobile platforms, such as cars, ships, airplanes [7]or UAV (Unmanned Aerial Vehicle) [8]. Examples of measurements using multiple viewing angles (azimuth and elevation angles) were performed, for example, in Mexico City, where mobile mini-DOAS were used to assess the outflow of NO 2 and HCHO [9] and trace gases profiles in the atmospheric layers, together with their temporal evolution. MAX-DOAS measurements of tropospheric NO 2 and SO 2 vertical column densities were made in North China [10]or in Spain for the HONO vertical distribution and their temporal evolution [11].Mobile DOAS measurements were also made byDunarea de Jos University of Galati in Romania,during the measurement campaigns promoted by ESA (European Spatial Agency),such as AROMAT (The Airborne ROmanian Measurements of Aerosols and Trace gases).…”