The effect of structure type on the validity of turbulent flux measurements by the eddy covariance technique

2017 ◽  
pp. 345-352
Author(s):  
O. Achiman ◽  
Y. Mekhmandarov ◽  
M. Pirkner ◽  
J. Tanny
Keyword(s):  
Eddy Covariance ◽  
Turbulent Flux ◽  
Structure Type ◽  
Eddy Covariance Technique ◽  
Flux Measurements ◽  
Effect Of Structure

Long-term energy flux measurements and energy balance over a small boreal lake using eddy covariance technique

2011 ◽  
Vol 116 (D2) ◽  
Author(s):  
Annika Nordbo ◽  
Samuli Launiainen ◽  
Ivan Mammarella ◽  
Matti Leppäranta ◽  
Jussi Huotari ◽  
...  
Keyword(s):  
Energy Balance ◽  
Eddy Covariance ◽  
Energy Flux ◽  
Eddy Covariance Technique ◽  
Boreal Lake ◽  
Flux Measurements ◽  
Term Energy

scholarly journals Disjunct eddy covariance technique for trace gas flux measurements

2001 ◽  
Vol 28 (16) ◽  
pp. 3139-3142 ◽  
Author(s):  
H. J. I. Rinne ◽  
A. B. Guenther ◽  
C. Warneke ◽  
J. A. de Gouw ◽  
S. L. Luxembourg
Keyword(s):  
Eddy Covariance ◽  
Trace Gas ◽  
Gas Flux ◽  
Eddy Covariance Technique ◽  
Flux Measurements

scholarly journals Non-invasive flux Measurements at the Benthic Interface: The Aquatic Eddy Covariance Technique

2017 ◽  
Vol 7 (1) ◽  
pp. 1-50 ◽  
Author(s):  
Peter Berg ◽  
Marie Lise Delgard ◽  
Ronnie N. Glud ◽  
Markus Huettel ◽  
Clare E. Reimers ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Non Invasive ◽  
Eddy Covariance Technique ◽  
Flux Measurements

scholarly journals ICOS eddy covariance flux-station site setup: a review

2018 ◽  
Vol 32 (4) ◽  
pp. 471-494 ◽  
Author(s):  
Corinna Rebmann ◽  
Marc Aubinet ◽  
HaPe Schmid ◽  
Nicola Arriga ◽  
Mika Aurela ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
High Frequency ◽  
Observation System ◽  
System Research ◽  
Sources And Sinks ◽  
Turbulent Fluctuations ◽  
Eddy Covariance Technique ◽  
Flux Measurements ◽  
Station Site

Abstract The Integrated Carbon Observation System Research Infrastructure aims to provide long-term, continuous observations of sources and sinks of greenhouse gases such as carbon dioxide, methane, nitrous oxide, and water vapour. At ICOS ecosystem stations, the principal technique for measurements of ecosystem-atmosphere exchange of GHGs is the eddy-covariance technique. The establishment and setup of an eddy-covariance tower have to be carefully reasoned to ensure high quality flux measurements being representative of the investigated ecosystem and comparable to measurements at other stations. To fulfill the requirements needed for flux determination with the eddy-covariance technique, variations in GHG concentrations have to be measured at high frequency, simultaneously with the wind velocity, in order to fully capture turbulent fluctuations. This requires the use of high-frequency gas analysers and ultrasonic anemometers. In addition, to analyse flux data with respect to environmental conditions but also to enable corrections in the post-processing procedures, it is necessary to measure additional abiotic variables in close vicinity to the flux measurements. Here we describe the standards the ICOS ecosystem station network has adopted for GHG flux measurements with respect to the setup of instrumentation on towers to maximize measurement precision and accuracy while allowing for flexibility in order to observe specific ecosystem features.

scholarly journals Technical note: Novel triple O<sub>2</sub> sensor aquatic eddy covariance instrument with improved time shift correction reveals central role of microphytobenthos for carbon cycling in coral reef sands

2021 ◽  
Vol 18 (19) ◽  
pp. 5381-5395
Author(s):  
Alireza Merikhi ◽  
Peter Berg ◽  
Markus Huettel
Keyword(s):  
Coral Reef ◽  
Eddy Covariance ◽  
Current Flow ◽  
Time Shift ◽  
Overlying Water ◽  
Flow Measurements ◽  
Eddy Covariance Technique ◽  
New Instrument ◽  
O2 Concentration ◽  
Flux Measurements

Abstract. The aquatic eddy covariance technique stands out as a powerful method for benthic O2 flux measurements in shelf environments because it integrates effects of naturally varying drivers of the flux such as current flow and light. In conventional eddy covariance instruments, the time shift caused by spatial separation of the measuring locations of flow and O2 concentration can produce substantial flux errors that are difficult to correct. We here introduce a triple O2 sensor eddy covariance instrument (3OEC) that by instrument design eliminates these errors. This is achieved by positioning three O2 sensors around the flow measuring volume, which allows the O2 concentration to be calculated at the point of the current flow measurements. The new instrument was tested in an energetic coastal environment with highly permeable coral reef sands colonised by microphytobenthos. Parallel deployments of the 3OEC and a conventional eddy covariance system (2OEC) demonstrate that the new instrument produces more consistent fluxes with lower error margin. 3OEC fluxes in general were lower than 2OEC fluxes, and the nighttime fluxes recorded by the two instruments were statistically different. We attribute this to the elimination of uncertainties associated with the time shift correction. The deployments at ∼ 10 m water depth revealed high day- and nighttime O2 fluxes despite the relatively low organic content of the coarse sediment and overlying water. High light utilisation efficiency of the microphytobenthos and bottom currents increasing pore water exchange facilitated the high benthic production and coupled respiration. 3OEC measurements after sunset documented a gradual transfer of negative flux signals from the small turbulence generated at the sediment–water interface to the larger wave-dominated eddies of the overlying water column that still carried a positive flux signal, suggesting concurrent fluxes in opposite directions depending on eddy size and a memory effect of large eddies. The results demonstrate that the 3OEC can improve the precision of benthic flux measurements, including measurements in environments considered challenging for the eddy covariance technique, and thereby produce novel insights into the mechanisms that control flux. We consider the fluxes produced by this instrument for the permeable reef sands the most realistic achievable with present-day technology.

scholarly journals Eddy covariance flux measurements confirm extreme CH<sub>4</sub> emissions from a Swiss hydropower reservoir and resolve their short-term variability

2011 ◽  
Vol 8 (9) ◽  
pp. 2815-2831 ◽  
Author(s):  
W. Eugster ◽  
T. DelSontro ◽  
S. Sobek
Keyword(s):  
Greenhouse Gas ◽  
Eddy Covariance ◽  
Land Surface ◽  
Lake Level ◽  
Driving Forces ◽  
Open Water ◽  
Short Term ◽  
Flux Measurements ◽  
Floating Chamber ◽  
Hydropower Reservoir

Abstract. Greenhouse gas budgets quantified via land-surface eddy covariance (EC) flux sites differ significantly from those obtained via inverse modeling. A possible reason for the discrepancy between methods may be our gap in quantitative knowledge of methane (CH4) fluxes. In this study we carried out EC flux measurements during two intensive campaigns in summer 2008 to quantify methane flux from a hydropower reservoir and link its temporal variability to environmental driving forces: water temperature and pressure changes (atmospheric and due to changes in lake level). Methane fluxes were extremely high and highly variable, but consistently showed gas efflux from the lake when the wind was approaching the EC sensors across the open water, as confirmed by floating chamber flux measurements. The average flux was 3.8 ± 0.4 μg C m−2 s−1 (mean ± SE) with a median of 1.4 μg C m−2 s−1, which is quite high even compared to tropical reservoirs. Floating chamber fluxes from four selected days confirmed such high fluxes with 7.4 ± 1.3 μg C m−2 s−1. Fluxes increased exponentially with increasing temperatures, but were decreasing exponentially with increasing atmospheric and/or lake level pressure. A multiple regression using lake surface temperatures (0.1 m depth), temperature at depth (10 m deep in front of the dam), atmospheric pressure, and lake level was able to explain 35.4% of the overall variance. This best fit included each variable averaged over a 9-h moving window, plus the respective short-term residuals thereof. We estimate that an annual average of 3% of the particulate organic matter (POM) input via the river is sufficient to sustain these large CH4 fluxes. To compensate the global warming potential associated with the CH4 effluxes from this hydropower reservoir a 1.3 to 3.7 times larger terrestrial area with net carbon dioxide uptake is needed if a European-scale compilation of grasslands, croplands and forests is taken as reference. This indicates the potential relevance of temperate reservoirs and lakes in local and regional greenhouse gas budgets.

Eddy covariance flux measurements of momentum, heat and carbon dioxide in Hudson Bay at the onset of sea ice melt 

2021 ◽  
Author(s):  
Richard Sims ◽  
Brian Butterworth ◽  
Tim Papakyriakou ◽  
Mohamed Ahmed ◽  
Brent Else
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Sea Ice ◽  
Eddy Covariance ◽  
Open Water ◽  
The Arctic ◽  
Gas Transfer ◽  
Hudson Bay ◽  
Flux Measurements ◽  
Ice Fraction

&lt;p&gt;Remoteness and tough conditions have made the Arctic Ocean historically difficult to access; until recently this has resulted in an undersampling of trace gas and gas exchange measurements. The seasonal cycle of sea ice completely transforms the air sea interface and the dynamics of gas exchange. To make estimates of gas exchange in the presence of sea ice, sea ice fraction is frequently used to scale open water gas transfer parametrisations. It remains unclear whether this scaling is appropriate for all sea ice regions. Ship based eddy covariance measurements were made in Hudson Bay during the summer of 2018 from the icebreaker CCGS Amundsen. We will present fluxes of carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;), heat and momentum and will show how they change around the Hudson Bay polynya under varying sea ice conditions. We will explore how these fluxes change with wind speed and sea ice fraction. As freshwater stratification was encountered during the cruise, we will compare our measurements with other recent eddy covariance flux measurements made from icebreakers and also will compare our turbulent CO&lt;sub&gt;2&amp;#160;&lt;/sub&gt;fluxes with bulk fluxes calculated using underway and surface bottle pCO&lt;sub&gt;2&lt;/sub&gt;&amp;#160;data.&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

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