CO2 and O2 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
Sinks for anthropogenic CO2 are very small
relative to natural fluxes
We need to understand current sinks to predict
future CO2 and climate
120
90
120
90
8 GtC/yr
Land
Humans
2000
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What do existing flask measurements tell us?
TransCom1 FF Gradients
Observations
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Regional scale is critical for linking to
underlying processes
(NRCS/USDA, 1997)
CHLOROPHYLL
(SeaWIFS, 2002)
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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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Using high frequency data makes signals bigger,
but the annual-mean signals are still very small
Flux footprint, in ppm(GtCyr-1)-1, for a 106 km2
chaparral region in the U.S. Southwest (Gloor et
al., 1999).
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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

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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
Flux footprint, in ppm(GtCyr-1)-1, for a 106 km2
chaparral region in the U.S. Southwest (Gloor et
al., 1999).
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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
RMT, Ltd., Russia

• 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

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Towers over 650 feet AGL in U.S. and proximity