In Situ Measurements of Atmospheric CO And Its Correlation With Nox And O3 at a Rural Mountain Site

Abstract

Ambient concentrations of CO, as well as NOx and O3, were measured as a part of the PARADE campaign conducted at the Taunus Observatory on the summit of the Kleiner Feldberg between the 8th of August and 9th of September 2011. These measurements were made in an effort to provide insight into the characteristics of the effects of both biogenic and anthropogenic emissions on atmospheric chemistry in the rural south-western German environment. The overall average CO concentration was found to be 100.3±18.1 ppbv (within the range of 71 to 180 ppbv), determined from 10-min averages during the summer season. The background CO concentration was estimated to be ~90 ppbv. CO and NOx showed bimodal diurnal variations with peaks in the late morning (10:00-12:00 UTC) and in the late afternoon (17:00-20:00 UTC). Strong correlations between CO and NOx indicated that vehicular emission was the major contributor to the notable CO plumes observed at the sampling site. Both local meteorology and backward trajectory analyses suggest that CO plumes were associated with anthropogenically polluted air masses transferred by an advection to the site from densely populated city sites. Furthermore, a good linear correlation of R 2 = 0.54 between CO and O3 (∆O3/∆CO=0.560±0.016 ppbv/ppbv) was observed, in good agreement with previous observations.

Investigation of reactive gases and methane variability in the coastal boundary layer of the central Mediterranean basin

“…Probably, this yearly behavior stress the influence of a more mixed/diluted PBL and a higher NO x degradation by OH. However, even the lowest CO/NO x values observed during cold months suggested only a limited direct influence of "fresh" vehicular traffic emissions (Li et al, 2015). More years of measurement are needed to understand if this represents a typical feature at this measurement site.…”

“…With the aim of shading light on anthropogenic emissions contributing to CO variability, we calculated the hourly CO/NO x ratio ( Figure S3), since this parameter can be used to attribute CO emissions to motor vehicular exhaust or other sources. However, it should be considered that several factors related to different emission sources or air-mass aging, photochemistry, mixing or dilution can affect ambient CO/NO x (Li et al, 2015). The monthly evolution of CO/ NO x , showed higher values from April to September, while the lowest CO/NO x (median values ~ 100 ppb/ppb, 75 th and 90 th percentiles lower than 200 ppb/ppb) were observed in October -December.…”

Day and night-time formation of organic nitrates at a forested mountain site in south-west Germany

“…During PARADE, NO measurements were made with a modified commercial chemiluminescence detector (CLD 790 SR), the operation of which is described by Li et al (2015). The detection limit for this instrument is 4 pptv in 2 s, with a total uncertainty of 4 %.…”

Laser induced fluorescence based detection of atmospheric nitrogen dioxide and comparison of different techniques during the PARADE 2011 field campaign

“…Overall, the data of the CLD is about 5 % below the median, but this difference is within the uncertainty of the CLD measurement. The reported uncertainty of the CLD for the NO 2 measurements is 105 ppt v or 10 % (Li et al, 2015). The slope and y-intercept are 0.95 ± 0.008 and − 0.1 ± 0.01 ppb v , respectively.…”