CO2, CH4, N2O, SF6 and CO greenhouse gas measurements at Jungfraujoch

The CO2, CH4, N2O and CO measurements complement the halogenated greenhouse gases measured as part of the HALCLIM / InGOS / AGAGE activities. The joint observations allow monitoring a comprehensive set of the most important greenhouse gases and make Jungfraujoch the best equipped high-altitude research station in this respect.

The GC-FID/ECD instrument in the Jungfraujoch laboratory with the thermally insulated box housing the loops and the 2-position valves to the right, the periphery box in the middle and the H2 generator to the left.

Continuous observations of carbon monoxide at Jungfraujoch are available since 1996 using commercially available Non-Dispersive Infrared Absorption technology (NDIR). In addition, in-situ measurements of CH4, N2O, and SF6 started in early 2005 with a custom-built gas chromatograph equipped with a flame ionization detector and an electron capture detector (GC-FID/ECD) allowing quasi-continuous analysis every 24 to 30 minutes.

The Cavity Ringdown Spectrometer (CRDS) for continuous CO2, CH4 and CO observations (top) with the custom-built calibration and drying unit (bottom) at Jungfraujoch.
In late 2009, CO2 and CH4 observations were initiated with a Wavelength-Scanned Cavity Ringdown Spectrometer (CRDS) coupled to a custom-built calibration and drying unit which records data in the Hz range. Due to its superior precision and the full temporal coverage, the CRDS instrument became the master instrument for CH4 observations while the GC-FID/ECD system is still running to ensure a seamless transition and for quality control purposes. The CRDS model for CO2 and CH4 was replaced in September 2011 by a newer CRDS model being capable to measure CO2, CH4 and CO. Since January 2012, the data recorded with CRDS are also used as the primary CO time series.
Off-axis integrated cavity output spectrometer (OA-ICOS) for continuous N2O and CO obser-vations at Jungfraujoch. A commercially available multi-inlet unit with custom-made modifi-cations (behind the screen) is used for calibration.

In December 2014, the measurements were complemented by high-resolution, continuous N2O measurements. To do so, Empa is operating an off-axis integrated cavity output spectrometer (OA-ICOS) next to the GC-FID/ECD system. The superior precision and the continuous operation of the OA-ICOS compared to GC-ECD allow measuring short-term N2O variations that could not be detected with gas chromatography before. The laser spectrometer is also capable of measuring CO and H2O with high precision. The availability of the H2O signal allows measuring without sample drying and calculating dry air mole fractions by applying a humidity correction to the fully unaltered humid gas stream accounting for dilution and spectroscopic effects.