Half or more of US NEE may be in mountainous regions US Elevation Map Niwot Ridge NEE % Area

Regional Atmospheric Continuous CO2 Network in the Rocky Mountains (Rocky RACCOON) Existing and Planned NACP CO2 Sites Existing () and Planned (O) Sites Potential Future Sites (O) http://www.eol.ucar.edu/~stephens/RACCOON (courtesy S. Denning)

Autonomous, Inexpensive, Robust CO2 Analyzer (AIRCOA) Goal: 0.1 ppm precision and 0.1 ppm reproducibility on 2.5 min. measurements $10K in parts ($20K total) and operates autonomously for months at a time

Laboratory intercomparisons Laboratory offsets less than 0.05 ppm (1-sigma = 0.13 ppm) Field surveillance tanks 2.5-month average field differences from assigned values 0.01 to 0.10 ppm (1-sigma = 0.10 to 0.13 ppm)

Automated web-based output http://www.eol.ucar.edu/~stephens/RACCOON