Universität zu Köln

Jentzsch, K., Schulz, A., Pirk, N., Foken, T., Crewell, S. and Boike, J. (2021). High Levels of CO2 Exchange During Synoptic-Scale Events Introduce Large Uncertainty Into the Arctic Carbon Budget. Geophys. Res. Lett., 48 (9). WASHINGTON: AMER GEOPHYSICAL UNION. ISSN 1944-8007

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Abstract

CO2 release from thawing permafrost is both a consequence of, and a driver for, global warming, making accurate information on the Arctic carbon cycle essential for climate predictions. Eddy covariance data obtained from Bayelva (Svalbard) in 2015, using well-established processing and quality control techniques, indicate that most of the annual net CO2 uptake is due to high CO2 flux events in winter that are associated with strong winds and probably relate to technical limitations of the gas analyzer. Emission events may relate to either (unidentified) instrumental limitations or to physical processes such as CO2 advection. Excluding the high winter uptake events yields an annual CO2 budget close to zero; whether or not these events are included can, therefore, have a considerable effect on carbon budget calculations. Further investigation will be crucial to pinpoint the factors causing these high CO2 flux events and to derive scientifically substantiated flux processing standards. Plain Language Summary Global warming is making Arctic soils thaw, with formerly frozen organic material decomposing and producing the greenhouse gas CO2. This CO2 release further amplifies the rise in temperature. In order to predict how our climate will develop in the future, we, therefore, need to investigate how much CO2 is released into the atmosphere and how much is taken up by plants. Strong CO2 release or uptake signals are not expected during the Arctic winter due to the reduced microbial and plant activity but have nevertheless been observed at Arctic sites. We have investigated CO2 exchanges during the winter of 2015 at the Bayelva site, Svalbard, using the eddy covariance technique. We found that high levels of CO2 emission and uptake occurred during periods with high wind speed and have a significant impact on the calculated net annual CO2 exchange. The apparent CO2 uptake is likely to be an artefact resulting from technical limitations of the instruments, while the high levels of CO2 emission are probably a result of physical processes. However, known physical mechanisms alone, such as episodic outbursts of CO2 stored within the snow, cannot adequately explain our observations. Additional measurements will be required to identify the processes at play. Key Points High levels of CO2 exchange during the Arctic winter, associated with high wind speeds, have a marked effect on the annual carbon budget Conventional flux measurement and calculation techniques are subject to large uncertainties under Arctic low-flux conditions Local abiotic processes cannot explain the high-flux events, suggesting advective flux contributions or unidentified instrumental limitations

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Jentzsch, K. UNSPECIFIED UNSPECIFIED UNSPECIFIED Schulz, A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Pirk, N. UNSPECIFIED UNSPECIFIED UNSPECIFIED Foken, T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Crewell, S. UNSPECIFIED UNSPECIFIED UNSPECIFIED Boike, J. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-591925
DOI:	10.1029/2020GL092256
Journal or Publication Title:	Geophys. Res. Lett.
Volume:	48
Number:	9
Date:	2021
Publisher:	AMER GEOPHYSICAL UNION
Place of Publication:	WASHINGTON
ISSN:	1944-8007
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language PATH EDDY COVARIANCE; DIOXIDE EXCHANGE; FLUX; TUNDRA; PERMAFROST; VARIABILITY; TERM; SITE Multiple languages Geosciences, Multidisciplinary Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/59192