CO 2 and O 2 Concentration Measurements
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CO2 and O2 Concentration Measurements
Britton Stephens, NCAR/ATD
Peter Bakwin, NOAA/CMDL
• Global carbon cycle
• Regional scale CO2 measurements
• Potential biases in NDIR CO2 measurements
• Results from the WLEF O2 measurement program
• Hands on: Calculating ppm from volts using different techniques
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The Global Carbon Cycle
Humans
Atmosphere
760 + 3/yr
Ocean
38,000
Land
2000
~90
~120
~120
8 GtC/yr
~90
“Sinks” for anthropogenic CO2 are very small relative to natural fluxes
We need to understand
current sinks to predict future
CO2 and climate
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Expected from fossil fuel emissions
Observations
TransCom1 FF Gradients
What do existing flask measurements tell us?
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Annual-mean CO2 Exchange (GtCyr-1)
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Regional scale is critical for linking to underlying processes
(NRCS/USDA, 1997)
(NRCS/USDA, 1997) (SeaWIFS, 2002)
CHLOROPHYLL
TEMPERATURE (C)
(IPCC, 2001)
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(LSCOP, 2002)
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TURC/NDVI Biosphere, Takahashi Ocean, EDGAR Fossil Fuel
(Ute Karstens and Martin Heimann, 2001)
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Flux footprint, in ppm(GtCyr-1)-1, for a 106 km2 chaparral region in the U.S. Southwest (Gloor et al., 1999).
Using high frequency data makes signals bigger, but the annual-mean signals are still very small:
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Assessing horizontal CO2 transport at eddy-flux sites similarly requires networks of independent, accurate CO2 measurements
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Takehome Points
• Strong needs exist for measuring regional and local scale continental CO2 gradients
• Measuring CO2 gradients with independent instruments requires careful attention to potential biases
• New models are also needed to extract information from continental CO2 measurements
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CO2 and O2 Concentration Measurements
Britton Stephens, NCAR/ATD
Peter Bakwin, NOAA/CMDL
• Global carbon cycle
• Regional scale CO2 measurements
• Potential biases in NDIR CO2 measurements
• Results from the WLEF O2 measurement program
• Hands on: Calculating ppm from volts using different techniques
![Page 13: CO 2 and O 2 Concentration Measurements](https://reader036.fdocuments.us/reader036/viewer/2022062322/568148da550346895db5f4a7/html5/thumbnails/13.jpg)
Flux footprint, in ppm(GtCyr-1)-1, for a 106 km2 chaparral region in the U.S. Southwest (Gloor et al., 1999).
Using high frequency data makes signals bigger, but the annual-mean signals are still very small:
To measure 0.2 GtCyr-1 source or sink to +/- 25% need to measure annual mean gradients to around +/- 0.2 ppm
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Intra- and Inter-laboratory agreement still not better than 0.2 ppm
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Atmospheric Observing Systems
Boulder, Colorado
NOAA SBIR
Robust, Precise, CO2 Analyzer for Unattended
Field Use
Under Development
• 1 part in 3000 in 1 minute or less
• 30 cc/min or less gas usage
• Unattended field deployment for 6 months or more
• $5,000 or less when manufactured in quantity
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Prototype Inexpensive/Autonomous CO2 System
Research items:
• Stability of CO2 in aluminum LPG cylinders
• Correction for zero drift between calibrations
Goals:
• 1-2 year service schedule
• Total installation ~ $2000
• 0.5 ppm accuracy
RMT, Ltd., Russia
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Towers over 650 feet AGL in U.S. and proximity