Intercomparison of in situ NDIR and column FTIR measurements of CO<sub>2</sub> at Jungfraujoch

Abstract

Abstract. We compare two CO2 time series measured at the High Alpine Research Station Jungfraujoch, Switzerland (3580 m a.s.l.), in the period from 2005 to 2013 with an in situ surface measurement system using a nondispersive infrared analyzer (NDIR) and a ground-based remote sensing system using solar absorption Fourier transform infrared (FTIR) spectrometry. Although the two data sets show an absolute shift of about 13 ppm, the slopes of the annual CO2 increase are in good agreement within their uncertainties. They are 2.04 ± 0.07 and 1.97 ± 0.05 ppm yr−1 for the FTIR and the NDIR systems, respectively. The seasonality of the FTIR and the NDIR systems is 4.46 ± 1.11 and 10.10 ± 0.73 ppm, respectively. The difference is caused by a dampening of the CO2 signal with increasing altitude due to mixing processes. Whereas the minima of both data series occur in the middle of August, the maxima of the two data sets differ by about 10 weeks; the maximum of the FTIR measurements is in the middle of January, and the maximum of the NDIR measurements is found at the end of March. Sensitivity analyses revealed that the air masses measured by the NDIR system at the surface of Jungfraujoch are mainly influenced by central Europe, whereas the air masses measured by the FTIR system in the column above Jungfraujoch are influenced by regions as far west as the Caribbean and the USA.The correlation between the hourly averaged CO2 values of the NDIR system and the individual FTIR CO2 measurements is 0.820, which is very encouraging given the largely different sampling volumes. Further correlation analyses showed, that the correlation is mainly driven by the annual CO2 increase and to a lesser degree by the seasonality. Both systems are suitable to monitor the long-term CO2 increase, because this signal is represented in the whole atmosphere due to mixing.

Comparison of Continuous In-Situ CO2 Measurements with Co-Located Column-Averaged XCO2 TCCON/Satellite Observations and CarbonTracker Model Over the Zugspitze Region

“…This may be explained by the fact that our TCCON column observations were calibrated to World Meteorological Organization (WMO) scale, while the cited column observations were not. Furthermore, the column observations by Schibig et al [16], showing a difference of 13 ppm with respect to surface measurements at the Jungfraujoch, were performed in the mid-infrared, not in the near-infrared as our TCCON observations. In this context, we note that Buschmann et al [30] showed that the sensitivity of mid-infrared CO 2 column retrievals is a factor of two lower in the troposphere compared to TCCON-type near-infrared retrievals used in our study.…”

“…This higher value is assumed to be due to the global averaging effect, while our results show a more specific signature of the Zugspitze region. Equally, Schibig et al [16] reported that correlations between the FTIR and in-situ NDIR measurements, both with and without seasonality, reached 0.82 as well.…”

Solvent‐ and Catalyst‐Free Carbon Dioxide Capture and Reduction to Formate with Borohydride Ionic Liquid

“…After we changed from pure CO 2 to 6 vol % CO 2 mixed with N 2 , we went a step further to use dry compressed air that had a CO 2 concentration of 380–420 ppm . As we know that the rate of reaction increases at higher temperatures from the DSC results, a temperature between 60 and 70 °C was selected.…”

Estimation of the fossil-fuel component in atmospheric CO<sub>2</sub> based on radiocarbon measurements at the Beromünster tall tower, Switzerland

“…As CO is usually co-emitted with CO 2 during incomplete combustion of fossil and other fuels, we have also computed a tracer ratio designated as ΔCO/ΔCO 2 from the enhancements in the in-situ measured CO and CO 2 mixing ratios over the Jungfraujoch background (Oney et al, 2016, In review). CO 2bg values were obtained by applying the robust extraction of baseline signal (REBS) statistical method to the continuous CO 2 measurements at the high altitude site Jungfraujoch (Schibig et al, 2016) with a band width of 60 days. Note that while R CO strictly refers to the ratio of ΔCO to fossil fuel CO 2 emissions, the ΔCO/ΔCO 2 ratio can be influenced by biospheric contribution as well as CO 2 emissions from non-fossil sources such as biofuels and biomass burning.…”