Three years of semicontinuous greenhouse gas measurements at the Puy de Dôme station (central France)

Abstract

Abstract. Three years of greenhouse gas measurements, obtained using a gas chromatograph (GC) system located at the Puy de Dôme station at 1465 m a.s.l. in central France, are presented. The GC system was installed in 2010 at Puy de Dôme and was designed for automatic and accurate semicontinuous measurements of atmospheric carbon dioxide, methane, nitrous oxide and sulfur hexafluoride mole fractions. We present in detail the instrumental setup and the calibration strategy, which together allow the GC to reach repeatabilities of 0.1 µmol mol −1 , 1.2 nmol mol −1 , 0.3 nmol mol −1 and 0.06 pmol mol −1 for CO 2 , CH 4 , N 2 O and SF 6 , respectively. The analysis of the 3-year atmospheric time series revealed how the planetary boundary layer height drives the mole fractions observed at a mountain site such as Puy de Dôme where air masses alternate between the planetary boundary layer and the free troposphere.Accurate long-lived greenhouse gas measurements collocated with 222 Rn measurements as an atmospheric tracer allowed us to determine the CO 2 , CH 4 and N 2 O emissions in the catchment area of the station. The derived CO 2 surface flux revealed a clear seasonal cycle, with net uptake by plant assimilation in the spring and net emission caused by the biosphere and burning of fossil fuel during the remainder of the year. We calculated a mean annual CO 2 flux of 1310 ± 680 t CO 2 km −2 . The derived CH 4 and N 2 O emissions in the station catchment area were 7.0 ± 4.0 t CH 4 km −2 yr −1 and 1.8 ± 1.0 t N 2 O km −2 yr −1 , respectively. Our derived annual CH 4 flux is in agreement with the national French inventory, whereas our derived N 2 O flux is 5 times larger than the same inventory.

How a European network may help with estimating methane emissions on the French national scale

“…Hourly means of continuous data are all reported on the same scale (NOAA2004). The measurements are made mostly by optical instruments, such as Picarro or Caribou instruments and by gas chromatographs at GIF and PUY (Lopez et al, 2015;Schmidt et al, 2014;Yver-Kwok et al, 2015). Taking into account failures and maintenance of the instruments, data are not available during the whole year, as indicated in Table 1 and on the time series in the Supplement (Sects.…”

Inverse modelling of European CH<sub>4</sub> emissions during 2006–2012 using different inverse models and reassessed atmospheric observations

“…These measurements have been rigorously qualitycontrolled within the InGOS project. The quality control includes regular measurements of target gases that monitor instrument performance and long-term stability (Hammer et al, 2013;Lopez et al, 2015;Schmidt et al, 2014;WMO, 1993). The instrument precision has been evaluated as a 24 h moving 1σ standard deviation of bracketing working standards (denoted "working standard repeatability").…”

“…These regional monitoring stations have been set up over the past years, especially in the United States (Andrews et al, 2014) and Europe (e.g. Levin et al, 1999;Lopez et al, 2015;Popa et al, 2010;Schmidt et al, 2014;Vermeulen et al, 2011). The measurements from these stations were used in a number of inverse modelling studies to estimate emissions at regional and national scales (Bergamaschi et al, 2010Ganesan et al, 2015;Henne et al, 2016;Kort et al, 2008;Manning et al, 2011;Miller et al, 2013).…”

Continuous atmospheric CO<sub>2</sub>, CH<sub>4</sub> and CO measurements at the OPE station in France from 2011 to 2018

“…Berhanu et al (2016) presented their system performance using precision, a metric based on the standard deviation of the 1-min target gas measurements, at 0.05ppm for CO2, 0.29ppb for CH4 and 2.79ppb for CO using a Picarro G2400 spectrometer over 19 months from 2013 to 2014. Lopez et al (2015) presented STR estimates for the gas chromatograph system used at Puy de dôme at 0.1ppm for CO2 and 1.2 ppb for CH4, for the years 2010-2013. 20…”