On quantifying the effect of spectroscopic correction error for an open-path gas analyzer on the upscaling of CO2 fluxes
Abstract
Korea Flux Monitoring Network (KoFlux) and Korean National Institute of Forest Science have been operating a network of ten eddy covariance (EC) flux towers in diverse forest ecosystems across the South Korean Peninsula to monitor carbon/water/energy fluxes. The open-path infrared gas analyzers (Model EC150, Campbell Scientific Inc.) have been employed to measure the fluxes at the four EC sites of KoFlux. For these sites, we encountered physiologically unreasonable rates of CO2 uptake during the dormant winter seasons. These negative fluxes were associated primarily with the spectroscopic correction of EC150, where the air temperature (measured with slow-response thermistor) was used to convert CO2 concentration (measured at high speed) to density. In this study, we examined the bias and uncertainty of the CO2 flux due to the spectroscopic correction errors, and analyzed the relationship between these errors in CO2 flux and the sensible heat flux (H, strongly correlated with the fluctuation of air temperature). We found a clear negative linear relationship between the error in CO2 flux and H based on the wintertime data from the three temperate forest sites, and the relationship was not site-specific. Errors in spectroscopic correction would result in the overestimation of annual carbon budget and we present the quantified effect of such errors on the upscaling of CO2 fluxes over the South Korean forests.
Acknowledgments: This study was carried out with the support of R&D Program for Forest Science Technology (Project No. 2017099A00-1719-BB01) provided by Korea Forest Service (Korea Forestry Promotion Institute).- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B41L2477C
- Keywords:
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- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 0426 Biosphere/atmosphere interactions;
- BIOGEOSCIENCES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0438 Diel;
- seasonal;
- and annual cycles;
- BIOGEOSCIENCES