A Multi-Year Record of Airborne Continuous CO2 in the U.S. Southern Great Plains
S. Biraud1, C. Sweeney2 and M.S. Torn1
1Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720; 510-486-6084, E-mail: SCBiraud@lbl.gov
2Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309
We report on three years of airborne measurements of continuous atmospheric CO2 concentrations over the Atmospheric Radiation Measurement Program (ARM) Climate Research Facility (ACRF) in the U.S. Southern Great Plains. These continuous measurements are collected weekly from a small aircraft (Cessna 206) on a series of horizontal legs ranging from 17,500 feet down to 1,500 feet above sea level. The continuous CO2 observations are measured using a CO2 analyzer built by Atmospheric Observing System Inc., based in Boulder, Colorado. The analyzer has non-imaging optics and negligible sensitivity to motion of platform. The NDIR Analyzer is the core element of the system. Accuracy, including bias, is approximately 0.1 ppm of CO2 Dry Mole Fraction at 1 Hz. Each flight lasts between 2.5 and 3 hours, yielding about 10,000 CO2 measurements per flight. Since November 2007, more than 150 continuous CO2 vertical profiles have been collected, along with NOAA ESRL 12-flask (carbon cycle gases and isotopes) packages for validation. Comparison between the continuous and flask CO2 measurements indicates a difference of no larger than 0.2 ppm.