Articles | Volume 7, issue 2
Atmos. Meas. Tech., 7, 647–687, 2014

Special issue: Carbon dioxide, other greenhouse gases, and related measurement...

Atmos. Meas. Tech., 7, 647–687, 2014

Research article 25 Feb 2014

Research article | 25 Feb 2014

CO2, CO, and CH4 measurements from tall towers in the NOAA Earth System Research Laboratory's Global Greenhouse Gas Reference Network: instrumentation, uncertainty analysis, and recommendations for future high-accuracy greenhouse gas monitoring efforts

A. E. Andrews1, J. D. Kofler1,2, M. E. Trudeau1,2,3, J. C. Williams1,4, D. H. Neff1,2, K. A. Masarie1, D. Y. Chao1,2, D. R. Kitzis1,2, P. C. Novelli1, C. L. Zhao1,2, E. J. Dlugokencky1, P. M. Lang1, M. J. Crotwell1,2, M. L. Fischer5, M. J. Parker6,7, J. T. Lee8, D. D. Baumann9, A. R. Desai10, C. O. Stanier11, S. F. J. De Wekker12, D. E. Wolfe1, J. W. Munger13, and P. P. Tans1 A. E. Andrews et al.
  • 1NOAA Earth System Research Laboratory, Boulder, CO, USA
  • 2Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
  • 3Cooperative Institute for Research in the Atmosphere, Colorado State University, Fort Collins, CO, USA
  • 4Science and Technology Corporation, Boulder, CO, USA
  • 5Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
  • 6Savannah River National Laboratory, Aiken, SC, USA
  • 7Savannah River Nuclear Solutions, LLC, Aiken, SC, USA
  • 8Center for Research on Sustainable Forestry, School of Forestry, University of Maine, Orono, ME, USA
  • 9Institute for Applied Ecosystem Studies, US Forest Service Northern Research Station, Rhinelander, WI, USA
  • 10Atmospheric & Oceanic Sciences Department, University of Wisconsin, Madison, WI, USA
  • 11Department of Chemical and Biochemical Engineering, University of Iowa, Iowa City, IA, USA
  • 12Department of Environmental Sciences, University of Virginia, Charlottesville, VA, USA
  • 13School of Engineering and Applied Science, Harvard University, Cambridge, MA, USA

Abstract. A reliable and precise in situ CO2 and CO analysis system has been developed and deployed at eight sites in the NOAA Earth System Research Laboratory's (ESRL) Global Greenhouse Gas Reference Network. The network uses very tall (> 300 m) television and radio transmitter towers that provide a convenient platform for mid-boundary-layer trace-gas sampling. Each analyzer has three sample inlets for profile sampling, and a complete vertical profile is obtained every 15 min. The instrument suite at one site has been augmented with a cavity ring-down spectrometer for measuring CO2 and CH4. The long-term stability of the systems in the field is typically better than 0.1 ppm for CO2, 6 ppb for CO, and 0.5 ppb for CH4, as determined from repeated standard gas measurements. The instrumentation is fully automated and includes sensors for measuring a variety of status parameters, such as temperatures, pressures, and flow rates, that are inputs for automated alerts and quality control algorithms. Detailed and time-dependent uncertainty estimates have been constructed for all of the gases, and the uncertainty framework could be readily adapted to other species or analysis systems. The design emphasizes use of off-the-shelf parts and modularity to facilitate network operations and ease of maintenance. The systems report high-quality data with > 93% uptime. Recurrent problems and limitations of the current system are discussed along with general recommendations for high-accuracy trace-gas monitoring. The network is a key component of the North American Carbon Program and a useful model for future research-grade operational greenhouse gas monitoring efforts.