1. 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

2. The Global Carbon Cycle
Atmosphere
/yr
“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
Ocean
38,000
Land
Humans
2000

3. What do existing flask measurements tell us?
TransCom1 FF Gradients
Expected from fossil
fuel emissions
Observations

4. Annual-mean CO2 Exchange (GtCyr-1)

5. Regional scale is critical for linking to underlying processes
TEMPERATURE (C)
(IPCC, 2001)
(NRCS/USDA, 1997)
(NRCS/USDA, 1997)
CHLOROPHYLL
(SeaWIFS, 2002)

6. Large gaps, cont not actually used
Other networks as well
Ocean and terrestrial obs too

7. (LSCOP, 2002)

8. (Ute Karstens and Martin Heimann, 2001)
TURC/NDVI Biosphere, Takahashi Ocean, EDGAR Fossil Fuel
(Ute Karstens and Martin Heimann, 2001)

9. 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).

10. Assessing horizontal CO2 transport at eddy-flux sites similarly requires networks of independent, accurate CO2 measurements

11. 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

12. 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

13. 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).

14. Intra- and Inter-laboratory agreement still not better than 0.2 ppm

15. 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

16. 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

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