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Journal Article

High-quality eddy-covariance CO2 budgets under cold climate conditions

MPS-Authors
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Kittler,  Fanny
Integrating surface-atmosphere Exchange Processes Across Scales - Modeling and Monitoring, Dr. Mathias Göckede, Department Biogeochemical Systems, Prof. M. Heimann, Max Planck Institute for Biogeochemistry, Max Planck Society;
IMPRS International Max Planck Research School for Global Biogeochemical Cycles, Max Planck Institute for Biogeochemistry, Max Planck Society;

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Heimann,  Martin
Department Biogeochemical Systems, Prof. M. Heimann, Max Planck Institute for Biogeochemistry, Max Planck Society;

/persons/resource/persons62444

Kolle,  Olaf
Service Facility Field Measurements & Instrumentation, O. Kolle, Max Planck Institute for Biogeochemistry, Max Planck Society;

/persons/resource/persons129255

Göckede,  Mathias
Integrating surface-atmosphere Exchange Processes Across Scales - Modeling and Monitoring, Dr. Mathias Göckede, Department Biogeochemical Systems, Prof. M. Heimann, Max Planck Institute for Biogeochemistry, Max Planck Society;

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BGC2676P.pdf
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Supplementary Material (public)
Citation

Kittler, F., Eugster, W., Foken, T., Heimann, M., Kolle, O., & Göckede, M. (2017). High-quality eddy-covariance CO2 budgets under cold climate conditions. Journal of Geophysical Research: Biogeosciences, 122(8), 2064-2084. doi:10.1002/2017JG003830.


Cite as: http://hdl.handle.net/11858/00-001M-0000-002D-C3E6-2
Abstract
This study aimed at quantifying potential negative effects of instrument heating to improve eddy covariance flux data quality in cold environments. Our overarching objective was to minimize heating-related bias in annual CO2 budgets from an Arctic permafrost system. We used continuous eddy-covariance measurements covering three full years within an Arctic permafrost ecosystem with parallel sonic anemometers operation with activated heating and without heating as well as parallel operation of open- and closed-path gas analyzers, the latter serving as a reference. Our results demonstrate that the sonic anemometer heating has a direct effect on temperature measurements while the turbulent wind field is not affected. As a consequence, fluxes of sensible heat are increased by an average 5 W m-2 with activated heating, while no direct effect on other scalar fluxes was observed. However, the biased measurements in sensible heat fluxes can have an indirect effect on the CO2 fluxes in case they are used as input for a density-flux WPL correction of an open-path gas analyzer. Evaluating the self-heating effect of the open-path gas analyzer by comparing CO2 flux measurements between open- and closed-path gas analyzers we found systematically higher CO2 uptake recorded with the open-path sensor, leading to a cumulative annual offset of 96 gC m-2, which was not only the result of the cold winter season but also due to substantial self-heating effects during summer. With an inclined sensor mounting, only a fraction of the self-heating correction for vertically mounted instruments is required.