Experimental Test of Density and Energy-Balance Corrections on Carbon Dioxide Flux as Measured Using Open-Path Eddy Covariance

2003 ◽  
Vol 95 (6) ◽  
pp. 1393-1403 ◽  
Author(s):  
J. M. Ham ◽  
J. L. Heilman
Keyword(s):  
Carbon Dioxide ◽  
Energy Balance ◽  
Eddy Covariance ◽  
Experimental Test ◽  
Carbon Dioxide Flux ◽  
Open Path ◽  
Balance Corrections

scholarly journals Dried, closed-path eddy covariance method for measuring carbon dioxide flux over sea ice

2018 ◽  
Vol 11 (11) ◽  
pp. 6075-6090 ◽  
Author(s):  
Brian J. Butterworth ◽  
Brent G. T. Else
Keyword(s):  
Carbon Dioxide ◽  
Sea Ice ◽  
Eddy Covariance ◽  
Co2 Flux ◽  
Carbon Dioxide Flux ◽  
The Arctic ◽  
Closed Path ◽  
Eddy Covariance Method ◽  
Open Path ◽  
Flux Measurements

Abstract. The Arctic marine environment plays an important role in the global carbon cycle. However, there remain large uncertainties in how sea ice affects air–sea fluxes of carbon dioxide (CO2), partially due to disagreement between the two main methods (enclosure and eddy covariance) for measuring CO2 flux (FCO2). The enclosure method has appeared to produce more credible FCO2 than eddy covariance (EC), but is not suited for collecting long-term, ecosystem-scale flux datasets in such remote regions. Here we describe the design and performance of an EC system to measure FCO2 over landfast sea ice that addresses the shortcomings of previous EC systems. The system was installed on a 10 m tower on Qikirtaarjuk Island – a small rock outcrop in Dease Strait located roughly 35 km west of Cambridge Bay, Nunavut, in the Canadian Arctic Archipelago. The system incorporates recent developments in the field of air–sea gas exchange by measuring atmospheric CO2 using a closed-path infrared gas analyzer (IRGA) with a dried sample airstream, thus avoiding the known water vapor issues associated with using open-path IRGAs in low-flux environments. A description of the methods and the results from 4 months of continuous flux measurements from May through August 2017 are presented, highlighting the winter to summer transition from ice cover to open water. We show that the dried, closed-path EC system greatly reduces the magnitude of measured FCO2 compared to simultaneous open-path EC measurements, and for the first time reconciles EC and enclosure flux measurements over sea ice. This novel EC installation is capable of operating year-round on solar and wind power, and therefore promises to deliver new insights into the magnitude of CO2 fluxes and their driving processes through the annual sea ice cycle.

scholarly journals Dried, closed-path eddy covariance method for measuring carbon dioxide flux over sea ice

2018 ◽  
Author(s):  
Brian J. Butterworth ◽  
Brent G. T. Else
Keyword(s):  
Carbon Dioxide ◽  
Sea Ice ◽  
Eddy Covariance ◽  
Co2 Flux ◽  
Carbon Dioxide Flux ◽  
The Arctic ◽  
Closed Path ◽  
Eddy Covariance Method ◽  
Open Path ◽  
Flux Measurements

Abstract. The Arctic marine environment plays an important role in the global carbon cycle. However, there remain large uncertainties in how sea ice affects air–sea fluxes of carbon dioxide (CO2), partially due to disagreement between the two main methods (enclosure and eddy covariance) for measuring CO2 flux (FCO2). The enclosure method has appeared to produce more credible FCO2 than eddy covariance (EC), but is not suited for collecting long-term, ecosystem-scale flux datasets in such remote regions. Here we describe the design and performance of an EC system to measure FCO2 over landfast sea ice that addresses the shortcomings of previous EC systems. The system was installed on a 10-m tower on Qikirtaarjuk Island – a small rock outcrop in Dease Strait located roughly 35 km west of Cambridge Bay, Nunavut in the Canadian Arctic Archipelago. The system incorporates recent developments in the field of air–sea gas exchange by measuring atmospheric CO2 using a closed-path infrared gas analyzer (IRGA) with a dried sample airstream, thus avoiding the known water vapor issues associated with using open-path IRGAs in low-flux environments. A description of the methods and the results from four months of continuous flux measurements from May through August 2017 are presented, highlighting the winter to summer transition from ice cover to open water. We show that the dried, closed-path EC system greatly reduces the magnitude of measured FCO2 compared to simultaneous open-path EC measurements, and for the first time reconciles EC and enclosure flux measurements over sea ice. This novel EC installation is capable of operating year-round on solar/wind power, and therefore promises to deliver new insights into the magnitude of CO2 fluxes and their driving processes through the annual sea ice cycle.

scholarly journals Vertical advection and nocturnal deposition of ozone over a boreal pine forest

2009 ◽  
Vol 9 (6) ◽  
pp. 2089-2095 ◽  
Author(s):  
Ü. Rannik ◽  
I. Mammarella ◽  
P. Keronen ◽  
T. Vesala
Keyword(s):  
Carbon Dioxide ◽  
Eddy Covariance ◽  
Turbulence Intensity ◽  
Carbon Dioxide Flux ◽  
Pine Forest ◽  
Night Time ◽  
Vertical Advection ◽  
Ozone Deposition ◽  
Storage Change ◽  
Ozone Sink

Abstract. Night-time ozone deposition for a Scots pine forest in Southern Finland was studied at the SMEAR II measurement station by evaluating the turbulent eddy covariance (EC), storage change and vertical advection fluxes. Similarly to night-time carbon dioxide flux, the eddy-covariance flux of ozone was decreasing with turbulence intensity (friction velocity), and storage change of the compound did not compensate the reduction (well-known night-time measurement problem). Accounting for vertical advection resulted in invariance of ozone deposition rate on turbulence intensity. This was also demonstrated for carbon dioxide, verified by independent measurements of NEE by chamber systems. The result highlights the importance of advection when considering the exchange measurements of any scalar. Analysis of aerodynamic and laminar boundary layer resistances by the model approach indicated that the surface resistance and/or chemical sink strength was limiting ozone deposition. The possible aerial ozone sink by known fast chemical reactions with sesquiterpenes and NO explain only a minor fraction of ozone sink. Thus the deposition is controlled either by stomatal uptake or surface reactions or both of them, the mechanisms not affected by turbulence intensity. Therefore invariance of deposition flux on turbulence intensity is expected also from resistance and chemical sink analysis.

scholarly journals EddyUH: an advanced software package for eddy covariance flux calculation for a wide range of instrumentation and ecosystems

2016 ◽  
Author(s):  
I. Mammarella ◽  
O. Peltola ◽  
A. Nordbo ◽  
L. Järvi ◽  
Ü. Rannik
Keyword(s):  
Carbon Dioxide ◽  
Water Vapour ◽  
Eddy Covariance ◽  
Closed Path ◽  
Software Packages ◽  
Spectral Correction ◽  
Open Path ◽  
Methane Fluxes ◽  
Water Vapour Fluxes ◽  
Processing Steps

Abstract. We have carried out an inter-comparison between EddyUH and EddyPro®, two public software packages for post-field processing of eddy covariance data. Datasets including carbon dioxide, methane and water vapour fluxes measured over two months at a wetland in Southern Finland and carbon dioxide and water vapour fluxes measured over three months at an urban site in Helsinki, were processed and analysed. The purpose was to estimate the flux uncertainty due to the use of different software packages and to evaluate the most critical processing steps, determining the largest deviations in the calculated fluxes. Turbulent fluxes calculated with a reference combination of processing steps were in good agreement, the systematic difference between the two software packages being up to 2% and 6.7% for half-hour and cumulative sum values, respectively. The raw data preparation and processing steps were consistent between the software packages, and most of the deviations in the estimated fluxes were due to the flux corrections. Among the different calculation procedures analysed, the spectral correction had biggest impact for closed-path latent heat fluxes, reaching nocturnal median value of 15% at the wetland site. We found up to 43% median value of deviation (with respect to the run with all corrections included) if closed path carbon dioxide flux is calculated without the dilution correction, while the methane fluxes were up to 10% lower without both dilution and spectroscopic corrections. The density (and spectroscopic) correction was the most critical step for open-path systems. However, we found also large spectral correction factors for the open-path methane fluxes, due to the sensor separation effect.

Air-sea carbon-dioxide flux estimated by eddy covariance method from a buoy observation

2012 ◽  
Vol 31 (6) ◽  
pp. 66-71 ◽  
Author(s):  
Yansong Huang ◽  
Jinbao Song ◽  
Juanjuan Wang ◽  
Conghui Fan
Keyword(s):  
Carbon Dioxide ◽  
Eddy Covariance ◽  
Carbon Dioxide Flux ◽  
Eddy Covariance Method

scholarly journals Addressing a systematic bias in carbon dioxide flux measurements with the EC150 and the IRGASON open-path gas analyzers

2016 ◽  
Vol 228-229 ◽  
pp. 349-359 ◽  
Author(s):  
M. Helbig ◽  
K. Wischnewski ◽  
G.H. Gosselin ◽  
S.C. Biraud ◽  
I. Bogoev ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Flux ◽  
Systematic Bias ◽  
Open Path ◽  
Flux Measurements

scholarly journals Net ecosystem CO<sub>2</sub> exchange measurements by the closed chamber method and the eddy covariance technique and their dependence on atmospheric conditions – a case study

2013 ◽  
Vol 6 (5) ◽  
pp. 8783-8805 ◽  
Author(s):  
M. Riederer ◽  
A. Serafimovich ◽  
T. Foken
Keyword(s):  
Carbon Dioxide ◽  
Eddy Covariance ◽  
Net Ecosystem Exchange ◽  
Carbon Dioxide Flux ◽  
Atmospheric Conditions ◽  
Closed Chamber ◽  
Carbon Dioxide Fluxes ◽  
Chamber Method ◽  
Eddy Covariance Technique ◽  
Closed Chamber Method

Abstract. Carbon dioxide flux measurements in ecosystem sciences are mostly conducted by eddy covariance technique or the closed chamber method. Also some comparisons have been performed. But there is a lack of detailed assessment of present differences and uncertainties. To determine underlying processes, a ten-day, side-by-side measurement of the net ecosystem exchange with both techniques was evaluated with regard to various atmospheric conditions during the diurnal cycle. It was found that, depending on the particular atmospheric condition, the chamber carbon dioxide flux was either: (i) equal to the carbon dioxide flux measured by the reference method eddy covariance, by day with well developed atmospheric turbulence, (ii) higher, in the afternoon in times of oasis effect, (iii) lower, predominantly at night while large coherent structure fluxes or high wind velocities prevailed, or, (iv) showed less variation in the flux pattern, at night while stable stratification was present. Due to lower chamber carbon dioxide fluxes at night, when respiration forms the net ecosystem exchange, and higher chamber carbon dioxide fluxes in the afternoon, when the ecosystem is still a net carbon sink, there are two complementary aspects resulting in an overestimation of the ecosystem sink capacity by the chamber of 40% in this study.

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