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 Organization

NO 23
Acronym Empa
Name Swiss Federal Laboratories for Materials Science and Technology
Address 1 Ueberlandstrasse 129
Address 2 8600 Duebendorf
Address 3 Switzerland
Country/Territory Switzerland
Website http://www.empa.ch/gaw

 Contact(s)

Name Martin Steinbacher
Prefix Dr.
Email martin.steinbacher@empa.ch
Organization No 23
Organization acronym Empa
Organization name Swiss Federal Laboratories for Materials Science and Technology
Organization country/territory Switzerland
Address 1 Ueberlandstrasse 129
Address 2 CH-8600 Duebendorf
Address 3 Switzerland
Country/territory Switzerland
Tel +41 58 765 4048
Fax +41 58 765 1122
Last updated date 2020-08-28


 Background observation
 UTC+01:00
 ppb
 9999-12-31 00:00:00 - 9999-12-31 23:59:59: WMO CH4 X2004A
 2005-01-01 00:00:00 - 2009-12-31 23:59:59: Agilent 6890N(Gas chromatography (FID))
 2010-01-01 00:00:00 - 2011-09-15 23:59:59: Picarro G1301(CRDS)
 2011-09-16 00:00:00 - 9999-12-31 23:59:59: Picarro G2401(CRDS)
 9999-12-31 00:00:00 - 9999-12-31 23:59:59: 10 (m)
 5 seconds
 GC-FID:
before December 2008: every 30min (alternating with air samples)
after December 2008: every 24min (alternating with air samples)
CRDS:
from January 2010: Calibrations are performed every 46 hours with two calibration gases. In addition, a target gas is analyzed every 15 hours to detect potential shorter term instrument sensitivity changes. mean precision for 20 mins of working standard analysis: < 0.02%
3 December 2016: Calibration frequency was reduced to one a week but calibration sequence is run 4 times in a row to identify/eliminate effects in the pressure regulators while sample refers stagnant for several days. Two target tanks are connected to timely identify instrumental or calibration issues.
The GC-FID data are not reported anymore after 2009. However, the GC-FID still ran next to the CRDS analyzer until summer 2016 and regular comparisons of the side-by-side observations are performed for quality control and a very good agreement between the two techniques for the multi-year overlap period is observed.
since December 2015: reference gases are prepared and analyzed by the ICOS Central Calibration Laboratory in Jena, Germany
 Quality assurance procedures involve time series plots, consistency checks; the expanded measurement uncertainty for the CRDS measurements (2010 - ongoing) is estimated to be:
U_CH4 = 2 * ((0.31 nmol mol-1)^2 + (3.61e-4 * c)^2)^(1/2)
with c = CH4 mole fraction in nmol mol-1.
which is largely determined by the uncertainty in the nominal values of the reference gases.
Standard deviation of repeated target tank measurements is < 0.5 ppb.
 [Hourly] From 2014 onwards: number of detections refers to the number of available 5-second averages within the respective hour; data are discarded when less than 240 5-second averages are available for the respective hour
 [Daily] From 2014 onwards: number of detections refers to the number of available 1-min averages within the respective day
From 2018 onwards: number of detections refers to the number of available hourly averages within the respective day
 [Monthly] From 2014 onwards: number of detections refers to the number of available 1-min averages within the respective month
From 2018 onwards: number of detections refers to the number of available daily averages within the respective month
 
 Operational/Reporting
 Sampling Environment : high-alpine, measurements in pristine air, usually negligible local sources. Surfaces are mostly covered by snow or ice apart from some steep slopes of bare rock. No vegetation or soil present in the vicinity.
Air intake : open-face, ambient
Sampling and Analysis Frequency : GC-FID:
30min till December 2008
24min since December 2008
CRDS:
data are continuously recorded in 2-sec (G1301)and 5-sec (G2401) intervals, respectively
Scientific Aim : long-term trend of background mixing ratios in Europe source allocations / regional emission estimates during pollution events
Description of Instruments : Samples analysed by GC-FID are dried prior to analysis by means of a Nafion dryer.
Since 2010, CH4 observations are performed with a commercially available instrument (Picarro Inc. G1301) based on the Wavelength-Scanned Cavity Ringdown Spectroscopy technique coupled to a custom-built calibration/drying unit. The sample air was dried prior to analysis by means of a Nafion dryer until August 2010. Along with CH4, the instrument is also capable to measure CO2 and H2O. Thus, the CH4 data can be corrected for interferences of remaining water traces. From August 2010 on, no water vapor removal was used anymore and CH4 dry air mixing ratios are determined by application of an empirical humidity correction to the fully unaltered humid gas stream accounting for dilution and pressure broadening effects.
The G1301 analyzer was replaced by a G2401 (Picarro Inc.) analyzer on 16 September 2011. From 16 September 2011 until 01 November 2017 and since 25 October 2019 the sample air is dried prior to analysis by means of a Nafion dryer.
 Wind direction: 1
 Wind speed: 1
 Relative humidity: 1
 Precipitation amount: 0
 Air pressure: 1
 Air temperature: 1
 Dew point temperature: 0
 Sea water temperature: 0
 Sea surface water temperature: 0
 Sea water salinity: 0
 Sea surface water salinity: 0
Meteorological data may remain as first provded, even when greenhouse gas data are updated.
 Meteorological data at Jungfraujoch are measured by MeteoSwiss as part of its operation of the SwissMetNet Network.
see www.meteoswiss.admin.ch/
and
Appenzeller et al., Monitoring climate at Jungfraujoch in the high Swiss Alpine region, Science of The Total Environment, 391 (2–3), 262-268, https://doi.org/10.1016/j.scitotenv.2007.10.005
for more information.
1  Zellweger C., L. Emmenegger, M. Firdaus, J. Hatakka, M. Heimann, E. Kozlova, T. G. Spain, M. Steinbacher, M. V. van der Schoot, B. Buchmann, 2016 - Assessment of recent advances in measurement techniques for atmospheric carbon dioxide and methane observations, Atmospheric Measurement Techniques, 9, 4737-4757, doi:10.5194/amt-9-4737-2016.