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

The Global Carbon Cycle Atmosphere 760 + 3/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

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

Annual-mean CO2 Exchange (GtCyr-1)

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

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

(LSCOP, 2002)

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

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).

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

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

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

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).

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

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

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

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