Atmospheric Carbon Dioxide Record from Westerland, Germany

Graphics    Digital Data

Investigators

Karin Uhse
Umweltbundesamt,
Offenbach, Germany

Martina Schmidt and Ingeborg Levin
Institut fuer Umweltphysik,
University of Heidelberg,
Heidelberg, Germany

Period of Record

1972-97

Methods

Air samples are collected from air intake lines. Continuous monitoring of atmospheric CO₂ is accomplished by alternating a flowing sample of ambient air with two reference gases of known concentrations. Determinations of CO₂ are made using a Siemens ULTRAMAT-3 nondispersive infrared gas analyzer. Before entering the analyzer, all gases are dried by passing them through a glass water vapor trap immersed in a cold alcohol bath. Mixtures of CO₂-in-N₂ are used for calibration gases.

Only technically biased values resulting from calibration problems or equipment malfunctions are removed. Daily mean values are calculated on the basis of half-hourly mean values related to local wind speed higher than 7.5 m/sec. Carrier gas corrections have been determined experimentally and applied on the basis of five CO₂-in-air standards calibrated by Scripps Institution of Oceanography in 1988. The relative precision of the half-hourly readings is ~1 part per million by volume (ppmv). More details about the sampling methods, data selection criteria, and corrections are provided in Grosch et al. (1981), Levin (1991), and Levin et al. (1995).

Westerland, Germany
Coastal station on Island of Sylt (North Sea)
54°56' N, 8°19' E

Trends

Atmospheric CO₂ concentrations at Westerland rose from ~329 parts per million by volume (ppmv) in 1973 to ~364 ppmv in 1997. The atmospheric CO₂ record from Westerland shows a seasonal pattern similar to other UBA sites; minimum values are recorded during July-September; maximum mixing ratios during November-March.

References

• Grosch, W., W. Fleck, and D. Jost. 1981. The increase of carbon dioxide at rural sites of Germany. Berichte aus dem Meßnetz des Umweltbundesamtes.
• Levin, I. 1991. Der Beitrag der fossilen Energieträger zum CO₂-Haushalt über dem europäischen Kontinent. Abschlußbericht zum Forschungsvorhaben FE 104 02627
• Levin, I., R. Graul, and N.B.A. Trivett. 1995. Long-term observations of atmospheric CO₂ and carbon isotopes at continental sites in Germany. Tellus 47B:23-34.
• Schmidt, M., R. Graul, H. Sartorius, and I. Levin. 1996. Carbon dioxide and methane in continental Europe: a climatology and ²²²Radon-based emission estimates. Tellus 48B:457-473.

8/11/1998 Prepared by Mónica Martínez and Tom Boden