'Breathing' of the terrestrial biosphere: lessons learned from a global network of carbon dioxide flux measurement systems

2008 ◽  
Vol 56 (1) ◽  
pp. 1 ◽  
Author(s):  
Dennis Baldocchi
Keyword(s):  
Carbon Dioxide ◽  
Eddy Covariance ◽  
Ecosystem Respiration ◽  
Flux Measurement ◽  
Co2 Exchange ◽  
Carbon Dioxide Flux ◽  
Lessons Learned ◽  
Global Network ◽  
Eddy Covariance Method ◽  
Carbon Dioxide Co2

Published eddy covariance measurements of carbon dioxide (CO2) exchange between vegetation and the atmosphere from a global network are distilled, synthesised and reviewed according to time scale, climate and plant functional types, disturbance and land use. Other topics discussed include history of the network, errors and issues associated with the eddy covariance method, and a synopsis of how these data are being used by ecosystem and climate modellers and the remote-sensing community. Spatial and temporal differences in net annual exchange, FN, result from imbalances in canopy photosynthesis (FA) and ecosystem respiration (FR), which scale closely with one another on annual time scales. Key findings reported include the following: (1) ecosystems with the greatest net carbon uptake have the longest growing season, not the greatest FA; (2) ecosystems losing carbon were recently disturbed; (3) many old-growth forests act as carbon sinks; and (4) year-to-year decreases in FN are attributed to a suite of stresses that decrease FA and FR in tandem. Short-term flux measurements revealed emergent-scale processes including (1) the enhancement of light use efficiency by diffuse light, (2) dynamic pulses in FR following rain and (3) the acclimation FA and FR to temperature. They also quantify how FA and FR respond to droughts and heat spells.

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.

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 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 Influence of Tidal Inundation on CO<sub>2</sub> Exchange between Salt Marshes and the Atmosphere

2017 ◽  
Author(s):  
Hafsah Nahrawi ◽  
Monique Y. Leclerc ◽  
Gengsheng Zhang ◽  
Roshani Pahari
Keyword(s):  
Eddy Covariance ◽  
Salt Marshes ◽  
Neap Tide ◽  
High Tide ◽  
Spring Tide ◽  
Co2 Exchange ◽  
Eddy Covariance Method ◽  
Set Up ◽  
Carbon Dioxide Co2 ◽  
Reduction Of Co2

Abstract. Salt marshes are among the most productive and dynamic ecosystems on Earth and globally sequester an average of 210 g C m−2 yr−1. To understand the role of this ecosystem in the carbon cycle and its changes as a result of rapid climate change and human disturbance, a baseline record particularly on carbon dioxide (CO2) exchange between this ecosystem and atmosphere needs to be established. The goal of this study is to determine the effects tide events on the exchange of CO2 in a salt marsh ecosystem dominated by Spartina alterniflora using the eddy-covariance method near Sapelo Island, GA. Two eddy-covariance systems were set up in July 2013 to capture 10 Hz data of CO2. Results show that during daytime high tide events, a reduction of CO2 exchange was observed. The conditions with a high tide to vegetation ratio had smaller CO2 exchange when compared to conditions with a low tide ratio. Total daytime monthly reduction of CO2 exchange for August 2014 was 15 %. A greater total reduction of CO2 exchange of 40 % was recorded for high tide events with tide ratio of 0.75–1.0. In comparison of the effect of neap tide and spring tide on CO2 exchange, neap tide days showed a greater CO2 exchange as compared to spring tide days for May and October 2014, respectively. The inclusion of such results has implications to quantify the carbon budget and its changes as sea level rises.

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 Greenhouse gas flux measurements in a forestry-drained peatland indicate a large carbon sink

2011 ◽  
Vol 8 (11) ◽  
pp. 3203-3218 ◽  
Author(s):  
A. Lohila ◽  
K. Minkkinen ◽  
M. Aurela ◽  
J.-P. Tuovinen ◽  
T. Penttilä ◽  
...  
Keyword(s):  
Carbon Sink ◽  
Accumulation Rate ◽  
Peat Soil ◽  
Net Ecosystem Exchange ◽  
Flux Measurement ◽  
Co2 Exchange ◽  
Co2 Uptake ◽  
Flux Measurements ◽  
Ch4 And N2o ◽  
Carbon Dioxide Co2

Abstract. Drainage for forestry purposes increases the depth of the oxic peat layer and leads to increased growth of shrubs and trees. Concurrently, the production and uptake of the greenhouse gases carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) change: due to the accelerated decomposition of peat in the presence of oxygen, drained peatlands are generally considered to lose peat carbon (C). We measured CO2 exchange with the eddy covariance (EC) method above a drained nutrient-poor peatland forest in southern Finland for 16 months in 2004–2005. The site, classified as a dwarf-shrub pine bog, had been ditched about 35 years earlier. CH4 and N2O fluxes were measured at 2–5-week intervals with the chamber technique. Drainage had resulted in a relatively little change in the water table level, being on average 40 cm below the ground in 2005. The annual net ecosystem exchange was −870 ± 100 g CO2 m−2 yr−1 in the calendar year 2005, indicating net CO2 uptake from the atmosphere. The site was a small sink of CH4 (−0.12 g CH4 m−2 yr−1) and a small source of N2O (0.10 g N2O m−2 yr−1). Photosynthesis was detected throughout the year when the air temperature exceeded −3 °C. As the annual accumulation of C in the above and below ground tree biomass (175 ± 35 g C m−2) was significantly lower than the accumulation observed by the flux measurement (240 ± 30 g C m−2), about 65 g C m−2 yr−1 was likely to have accumulated as organic matter into the peat soil. This is a higher average accumulation rate than previously reported for natural northern peatlands, and the first time C accumulation has been shown by EC measurements to occur in a forestry-drained peatland. Our results suggest that forestry-drainage may significantly increase the CO2 uptake rate of nutrient-poor peatland ecosystems.

scholarly journals Air-Sea Fluxes of CO<sub>2</sub> and CH<sub>4</sub> from the Penlee Point Atmospheric Observatory on the South West Coast of the UK

2016 ◽  
Author(s):  
M. Yang ◽  
T. G. Bell ◽  
F. E. Hopkins ◽  
V. Kitidis ◽  
P. W. Cazenave ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
West Coast ◽  
Phytoplankton Bloom ◽  
Flux Measurement ◽  
Sensible Heat ◽  
The South ◽  
Eddy Covariance Method ◽  
Spring Phytoplankton Bloom ◽  
South West ◽  
South West Coast

Abstract. We present air-sea fluxes of carbon dioxide (CO2), methane (CH4), momentum, and sensible heat measured by the eddy covariance method from the recently established Penlee Point Atmospheric Observatory (PPAO) on the South West coast of the United Kingdom. Measurements from the southwest direction (background marine air) at three different sampling heights (approximately 15, 18, 27 m above mean sea level, AMSL) in three different periods during 2014–2015 are shown. At sampling heights ≥ 18 m AMSL, measured fluxes of momentum and sensible heat demonstrate reasonable agreement with their expected transfer rates over the open ocean. This confirms the suitability of PPAO for air-sea exchange measurements. We observed reductions in the air-to-sea fluxes of CO2 from spring to summer in both years, which coincided with the breakdown of the spring phytoplankton bloom. At all sampling heights, mean CH4 fluxes were positive, suggesting marine emissions. Higher CH4 fluxes were observed during rising tides (20&amp;pm;3; 29&amp;pm;6; 38&amp;pm;3 μmole m−2 d−1 at 15, 27, 18 m AMSL) than during falling tides (14&amp;pm;2; 21&amp;pm;5; 22&amp;pm;2 μmole m−2 d−1, respectively), consistent with an elevated CH4 source from an estuarine outflow driven by local tidal circulation. Based on observations at PPAO, we also estimate the detection limit of the eddy covariance CH4 flux measurement to be ~20 μmole m−2 d−1 over hourly timescales (~4 μmole m−2 d−1 over 24 hours).

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