scholarly journals Comparison between static chamber and tunable diode laser-based eddy covariance techniques for measuring nitrous oxide fluxes from a cotton field

2013 ◽  
Vol 171-172 ◽  
pp. 9-19 ◽  
Author(s):  
Kai Wang ◽  
Xunhua Zheng ◽  
Mari Pihlatie ◽  
Timo Vesala ◽  
Chunyan Liu ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Diode Laser ◽  
Eddy Covariance ◽  
Tunable Diode Laser ◽  
Cotton Field ◽  
Static Chamber

scholarly journals Towards standards for measuring greenhouse gas fluxes from agricultural fields using instrumented towers

2006 ◽  
Vol 86 (3) ◽  
pp. 373-400 ◽  
Author(s):  
E. Pattey ◽  
G. Edwards ◽  
I B Strachan ◽  
R L Desjardins ◽  
S. Kaharabata ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Nitrous Oxide ◽  
Greenhouse Gas ◽  
Diode Laser ◽  
Eddy Covariance ◽  
Tunable Diode Laser ◽  
Trace Gas ◽  
Noise Characteristics ◽  
Short Period ◽  
Flux Measurements

This is a discussion of the available technology for measuring turbulent fluxes using instrumented towers. This review focuses on the flux measurements of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) for agricultural systems and the development of standards and protocols for measuring them. Agroecosystems present unique challenges because they undergo large leaf area index (LAI) and canopy architecture changes in a relatively short period of time (i.e., months) coupled with the fact that many of the greenhouse gas sources are diffuse. This review examines all aspects of the theory and application of the micrometeorological techniques, with focus on the flux gradient, eddy accumulation and eddy covariance techniques. Instrument placement, sens or response and noise characteristics are also explored. Innovative applications of micrometeorological methods are discussed for closed- and open-path trace gas sensors and commonly used meteorological instrumentation. The use of fast response single-pass optical tunable diode laser (i.e., CH4, N2O) and infrared gas analyzers (i.e., CO2, H2O) is described. Consideration is also taken of the trace gas sensors’flow system design, mixing ratio measurement, and data acquisition and reduction requirements for micrometeorological flux measurement. Procedures are outlined for the meteorological instrumentation necessary for eddy covariance-based energy budget measurement including ultrasonic anemometry. Key words: Tower-based greenhouse gas flux measurements, nitrous oxide, methane, carbon dioxide, tunable diode laser

Spring thaw and growing season N2O emissions from a field planted with edible peas and a cover crop

2008 ◽  
Vol 88 (2) ◽  
pp. 241-249 ◽  
Author(s):  
Elizabeth Pattey ◽  
Lynda G Blackburn ◽  
Ian B. Strachan ◽  
Ray Desjardins ◽  
Dave Dow
Keyword(s):  
Nitrous Oxide ◽  
Diode Laser ◽  
Cover Crop ◽  
Growing Season ◽  
Dairy Manure ◽  
Cattle Manure ◽  
Tunable Diode Laser ◽  
Nitrous Oxide Emissions ◽  
Manure Application ◽  
Continuous Measurements

Nitrous oxide emissions are highly episodic and to accurately quantify them annually, continuous measurements are required. A tower-based micrometeorological measuring system was used on a commercial cattle farm near Cô teau-du-Lac, (QC, Canada) during 2003 and 2004 to quantify N2O emissions associated with the production of edible peas. It was equipped with an ultrasonic anemometer and a fast-response closed-path tunable diode laser. Continuous measurements of N2O fluxes were made during the spring thaw following corn cultivation in summer 2002, then during an edible pea growing season, followed by cattle manure application, cover crop planting and through until after the next spring ploughing. The cumulative N2O emissions of 0.7 kg N2O-N ha-1 during the initial snowmelt period following corn harvest were lower than expected. Sustained and small N2O emissions totalling 1.7 kg N2O-N ha-1 were observed during the growing season of the pea crop. Solid cattle manure applied after the pea harvest generated the largest N2O emissions (1.9 kg N2O-N ha-1 over 10 d) observed during the entire sampling period. N2O emissions associated with the cover crop in the fall were mostly influenced by manure application and totalled 0.8 kg N2O-N ha-1. For the subsequent spring thaw period, N2O emissions were 0.8 kg N2O-N ha-1. This represents approximately 15% of the annual emissions for the edible pea-cover crop system, which totalled 5.6 kg N2O-N ha-1 over the measuring periods. There was little difference in spring thaw N2O emissions between the two growing seasons of corn and edible pea-cover crop. Key words: Nitrous oxide emissions, legumes, snowmelt, dairy manure, tunable diode laser, flux tower

scholarly journals Evaluation of a lower-powered analyser and sampling system for eddy-covariance measurements of nitrous oxide fluxes

2017 ◽  
Author(s):  
Shannon E. Brown ◽  
Steve Sargent ◽  
Claudia Wagner-Riddle
Keyword(s):  
Frequency Response ◽  
Diode Laser ◽  
Eddy Covariance ◽  
Tunable Diode Laser ◽  
Closed Path ◽  
Laser Absorption ◽  
Eddy Covariance System ◽  
Diode Laser Absorption ◽  
New System ◽  
Absorption Spectrometer

Abstract. Nitrous oxide (N2O) fluxes measured using the eddy-covariance method capture the spatial and temporal heterogeneity of N2O emissions. Most closed-path trace-gas analyzers for eddy-covariance measurements have large-volume, multi-pass absorption cells that necessitate high flow rates for ample frequency response, thus requiring high-power sample pumps. Other sampling system components, including rain caps, filters, dryers, and tubing can also degrade system frequency response. This field trial tested the performance of a closed-path eddy-covariance system for N2O flux measurements with improvements to use less power while maintaining the frequency response. The new system consists of a thermoelectrically cooled tunable diode laser absorption spectrometer configured to measure both N2O and carbon dioxide (CO2). The system features a relatively small, single- pass sample cell (200 ml) that provides good frequency response with a lower-powered pump (~ 250 W). A new filterless intake removes particulates from the sample air stream with no additional mixing volume that could degrade frequency response. A single-tube dryer removes water vapor from the sample to avoid the need for density or spectroscopic corrections, while maintaining frequency response. This eddy-covariance system was collocated with a previous tunable diode laser absorption spectrometer model to compare N2O and CO2 flux measurements for two full growing seasons (May 2015 to October 2016) in a fertilized cornfield in Southern Ontario, Canada. Both spectrometers were placed outdoors at the base of the sampling tower demonstrating ruggedness for a range of environmental conditions (minimum to maximum daily temperature range: −26.1 to 31.6 °C). The new system rarely required maintenance. An in situ frequency response test demonstrated that the cutoff frequency of the new system was better than the old system (3.5 Hz compared to 2.30 Hz), and similar to that of a closed-path CO2 eddy- covariance system (4.05 Hz) using shorter tubing and no dryer that was also collocated at the site. Values of the N2O fluxes were similar between the two spectrometer systems (slope = 1.01, r2 = 0.96); CO2 fluxes as measured by the short-tubed eddy-covariance system and the two spectrometer systems correlated well (slope = 1.03, r2 = 0.998). The new lower-powered tunable diode laser absorption spectrometer configuration with the filterless intake and single-tube dryer showed promise for deployment in remote areas.

Tunable diode laser measurement of nitrous oxide in air

1980 ◽  
Vol 7 (12) ◽  
pp. 1093-1096 ◽  
Author(s):  
Peter S. Connell ◽  
Robert A. Perry ◽  
Carleton J. Howard
Keyword(s):  
Nitrous Oxide ◽  
Diode Laser ◽  
Tunable Diode Laser ◽  
Laser Measurement
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