Replacing the AMOR with the miniDOAS in the ammonia monitoring network in the Netherlands

Abstract

Abstract. In this paper we present the continued development of the miniDOAS, an active differential optical absorption spectroscopy (DOAS) instrument used to measure ammonia concentrations in ambient air. The miniDOAS has been adapted for use in the Dutch National Air Quality Monitoring Network. The miniDOAS replaces the life-expired continuous-flow denuder ammonia monitor (AMOR). From September 2014 to December 2015, both instruments measured in parallel before the change from AMOR to miniDOAS was made. The instruments were deployed at six monitoring stations throughout the Netherlands. We report on the results of this intercomparison.Both instruments show a good uptime of ca. 90 %, adequate for an automatic monitoring network. Although both instruments produce 1 min values of ammonia concentrations, a direct comparison on short timescales such as minutes or hours does not give meaningful results because the AMOR response to changing ammonia concentrations is slow. Comparisons between daily and monthly values show good agreement. For monthly averages, we find a small average offset of 0.65 ± 0.28 µg m −3 and a slope of 1.034 ± 0.028, with the miniDOAS measuring slightly higher than the AMOR. The fast time resolution of the miniDOAS makes the instrument suitable not only for monitoring but also for process studies.

Ammonia and PM2.5 Air Pollution in Paris during the 2020 COVID Lockdown

“…By dividing the integrated concentration by the length of the absorption path, the average NH 3 concentration (in µg/m 3 ) is obtained over the optical path [54]. The mini-DOAS system was evaluated during dedicated field campaigns, which demonstrated its reliability for measuring NH 3 concentrations over an urban area [55] and NH 3 vertical profiles [56] as well as its adequacy for long-term monitoring of NH 3 in an air quality network [57].…”

Quantification of Atmospheric Ammonia Concentrations: A Review of Its Measurement and Modeling

“…In the Netherlands, the Dutch National Air Quality Monitoring Network (LML: Landelijk Meetnet Luchtkwaliteit) and the Measuring Ammonia in Nature Network (MAN) have been making measurements of [NH 3 ] across the Netherlands since 1993 and 2005, respectively. The LML reports hourly [NH 3 ] since 1993 at eight sites and since 2014 at six sites using continuous-flow denuders (AMORs: Amanda for MOnitoring RIVM; Wyers et al [54]) and currently miniDOAS [59], and in two sites, triplets of passive samplers [60] for monthly mean values. While the LML provides a high temporal resolution, its low spatial distribution is compensated by over 300 sites of MAN that provide monthly passive sampling measurements of [NH 3 ].…”

Data assimilation of CrIS NH<sub>3</sub> satellite observations for improving spatiotemporal NH<sub>3</sub> distributions in LOTOS-EUROS

“…Initially, continuous flow denuders from AMOR were used, which have a reported uncertainty of at least 9 % for hourly concentrations (Blank et al, 2001). Around 2016, the AMOR instruments were replaced by miniDOAS instruments (Berkhout et al, 2017), which are active differential optical absorption spectroscopes. For evaluation of the wet deposition fields, observations from wetonly samplers from the Dutch Landelijk Meetnet Regenwatersamenstelling (LMRe) network (van Zanten et al, 2017), whose locations largely overlap with the LML network, and the UBA network (Schaap et al, 2018) are used.…”