HR: 1340h
AN: B23A-0927    [Abstracts]
TI: Uncertainty Analysis of CO$_{2}$ Standard Transfer via NDIR Analyzers in the NOAA Climate Monitoring and Diagnostics Laboratory from 1979 to 2004
AU: * Zhao, C
EM: Conglong.Zhao@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
AU: Tans, P P
EM: Pieter.Tans@noaa.gov
AF: NOAA Climate Monitoring and Diagnostics Laboratory, NOAA/OAR R/CMDL1, 325 Broadway, Boulder, CO 80305 United States
AU: Thoning, K W
EM: Kirk.W.Thoning@noaa.gov
AF: NOAA Climate Monitoring and Diagnostics Laboratory, NOAA/OAR R/CMDL1, 325 Broadway, Boulder, CO 80305 United States
AU: Kitzis, D R
EM: Duane.R.Kitzis@noaa.gov
AF: Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO 80309 United States
AU: Andrews, A E
EM: Arlyn.Andrews@noaa.gov
AF: NOAA Climate Monitoring and Diagnostics Laboratory, NOAA/OAR R/CMDL1, 325 Broadway, Boulder, CO 80305 United States
AB: At present, state of art, non-dispersive infrared (NDIR) analyzers offer the most precise method of CO$_{2}$ detection. However, this technique requires very accurately calibrated standard gases. On the basis of the WMO (World Meteorological Organization) CO$_{2}$ Expert Meeting in 1975, the CO$_{2}$ standards are classified as WMO primary, secondary, tertiary, and working standards according to intended use. The primary standards are used to assign precise CO2 concentration values to the secondary standards which are maintained by each country as national standards. From 1979 through 1996, The CMDL secondary standards have been calibrated by the Scripps Institute of Oceanography (SIO) against the WMO primary standards approximately every 3 years. From mid-1996 to 2001, the assigned CO$_{2}$ values of the primaries have been jointly based on the SIO and CMDL manometric measurements, and completely on the CMDL manometric measurements alone from 2001 to the present. The secondary standards are transferred via NDIR analyzers to all other reference gas tanks, which are used routinely for measuring atmospheric CO$_{2}$ concentrations in the CMDL flask sampling network and at the CMDL observatories. In this presentation, the uncertainties for each reference tank calibrations by the NDIR against the secondary standards from 1979 to present are analyzed. The calibration uncertainties are about 0.03 ¨mol/mol from September 1979 to March 1986, 0.007 ¨mol/mol from April 1986 to August 1999, and 0.01 ¨mol/mol from September 1999 to present. On the basis of these analyses, the total measuring uncertainties versus the WMO primary standards in the CMDL flask network and the observatories are estimated. These estimates can be considered as the upper limit of the precisions for determining atmospheric CO$_{2}$ concentrations during the period.
DE: 1694 Instruments and techniques
DE: 1610 Atmosphere (0315, 0325)
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0394 Instruments and techniques
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting