Two Figaro TGS 2600 sensors were installed at the Toolik Wet Sedge site in late June 2012 to 2018. The TGS 2600 was the first low-cost solid state sensor that shows a weak response to ambient levels of methane (i.e., range ~1.8–2.7 µmol mol–1). Reference CH4 mole fractions were measured by a Fast Methane Analyser during the years 2012–2016 which was replace by a Fast Greenhouse Gas Analyzer (Los Gatos Research, Inc., San Jose, CA, U.S.A.) in 2016. Data were used in the Eugster et al. (2020) study on Long-term reliability of the Figaro TGS 2600 solid-state methane sensor under low Arctic conditions at Toolik lake, Alaska (doi:10.5194/amt-2019-402)
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Field measurements were carried out at the Toolik wet sedge site (TWE, 68°37027.6200 N, 149°36008.1000 W, 728.14 m elevation, WGS 84 datum) where seasonal eddy covariance ﬂux measurements were carried out during the summer seasons of 2010–2015 and partially during winters starting in 2014 until 15 June 2016, with the continuation as a meteorological station until present.
Two Figaro TGS 2600 sensors were installed at the TWE site in late June 2012. The TGS 2600 is sensitive to methane at low concentrations, but also to hydrogen, carbon monoxide, iso-butane, and ethanol. It is the only low-cost solid-state sensor that we are aware off or which the manufacturer indicates a sensitivity to methane even under ambient (~2 µmol mol–1) methane concentrations, whereas most other sensors are only sensitive at concentrations that exceed ambient levels by at least one or two orders of magnitude. The TWE site receives line power from the Toolik Field Station (TFS) power generator. During the snow and ice-free summer season (typically late June to mid-August) measurements are almost interruption free, but during the cold season (typically September to late May) longer power interruptions limit the winter data coverage. Nevertheless, this is the ﬁrst study that provides low-cost sensor methane mole fraction measurements over a temperature range from Arctic winter temperatures of –41°C and to a relatively balmy 27°C during short periods of the Arctic summer. Reference CH4 mole fractions were measured by a Fast Methane Analyzer (FMA, Los Gatos Research, Inc., San Jose, CA, USA; years 2012–2016) which was replace by a Fast Greenhouse Gas Analyzer for combined CH4/CO2/H2O concentration measurements (FGGA, Los Gatos Research, Inc., San Jose, CA, U.S.A.; since 2016). Until 18 June 2016 the CH4 concentrations were calculated as 1-minute averages from the raw eddy covariance ﬂux data ﬁles. We report all gas mole fractions in μmol mol−1 or nmol mol−1. The FMA and FGGA sampling rate was set to 20 Hz, and the ﬂow rate of sample air was ca. 20 L min−1. After the termination of eddy covariance ﬂux measurements, the FGGA measurements were continued with the instrument’s80 internal pump (ﬂow rate ca. 0.65 L min−1) with 1 Hz raw data sampling. In addition to digital recording, the CH4 signal was converted to an analog voltage that was recorded on a CR23X data logger (Campbell Scientiﬁc Inc. [CSI], Logan, UT, USA). Because the TGS 2600 sensors only show a weak response to CH4, but are highly sensitive to temperature and humidity, a
LinPicco A05 Basic sensor (IST Innovative Sensor Technology, Wattwil, Switzerland) was added next to the TGS 2600.
Calculation: See publication (under details)
For details see:
Eugster, W., Laundre, J., Eugster, J., and Kling, G. W.: Long-term reliability of the Figaro TGS 2600 solid-state methane sensor under low Arctic conditions at Toolik lake, Alaska, Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2019-402
and the final version accessible via the discussion paper referenced above.
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