The NOAA nitrous oxide standard scale for atmospheric observations

Abstract

A new nitrous oxide (N2O) calibration scale has been developed for atmospheric observations. The NOAA‐2006 N2O scale is based on gravimetrically prepared compressed gas standards. This scale supercedes the NOAA‐2000 scale, which was accepted by the community of experts within the World Meteorological Organization Global Atmosphere Watch program (GAW) as the GAW reference standard. The new scale is defined by thirteen “daughter” standards with dry air mole fractions ranging from 261–371 parts‐per‐billion (nmol mol−1, ppb). These were derived from four part‐per‐million (mmol mol−1, ppm) level “parents”. Standards were evaluated using gas chromatography with electron capture detection. The daughter standards are internally consistent with a standard deviation of residuals of 0.33 ppb, and there is essentially no detectable difference among “cousins” (standards prepared from different parents). The NOAA‐2006 scale is 0.19 ppb lower than the NOAA‐2000 scale at 320 ppb. The global mean N2O mixing ratio (dry air mole fraction), calculated from in situ observations at five monitoring sites was 318.46 ppb in 2004 on the new scale. The NOAA‐2006 scale compares well with other scales based on comparisons of compressed gas standards. The NOAA‐2006 scale is, on average, 0.23% higher than that defined by NIST Standard Reference Materials 2608 and 2609, and an average of 0.01% lower than the Scripps Institution of Oceanography SIO‐98 scale over the range 298–319 ppb.

Validation of revised methane and nitrous oxide profiles from MIPAS–ENVISAT

“…Their high precision (CH 4 : 1.5 ppbv precision Dlugokencky et al, 2009; N 2 O: 0.2 ppbv precision Hall et al, 2007) compared to the various satellite instruments, makes them a valuable reference. MIPAS does not measure trace gas volume mixing ratios at the surface, which makes a direct comparison to surface data difficult.…”

“…We compared MIPAS N 2 O to the Combined Nitrous Oxide data product from the GMD at NOAA/ESRL (Hall et al, 2007;Elkins and Dutton, 2009). The measurements of 13 sites stationed at latitudes between 89.98 • S and 82.45 • N were used to calculate a global mean.…”

Atmospheric constraints on 2004 emissions of methane and nitrous oxide in North America from atmospheric measurements and a receptor-oriented modeling framework

“…All flasks were analyzed at NOAA/ESRL for CO 2 , CO, CH 4 , H 2 , SF 6 , and N 2 O dry air mole fractions. Methane and nitrous oxide measurements used here are calibrated on the NOAA2004 (Dlugokencky et al 2005) and NOAA2006 (Hall et al 2007) scales, respectively. Vertical profiling measurements used in the methane analysis were collected at three sites representing different regions of North America: a remote plain site in Briggsdale, Colorado (CAR, 40.378 N, 7104.308 W, 2000-8000 masl), a remote forested site in Park Falls, Wisconsin (LEF,45.938 N,790.278 W, 500-4000 masl), and a more urban site in Worcester, Massachusetts (NHA,42.958 N,770.638 W, 500-7000 masl).…”

Evaluation of a new JMA aircraft flask sampling system and laboratory trace gas analysis system

“…Their standards are sent to the Central Calibration Laboratory (CCL) for calibration against the World Meteorological Organization (WMO) mole fraction scales for CO 2 (Zhao and Tans, 2006), CH 4 (Dlugokencky et al, 2005), CO (Novelli et al, 2003), and N 2 O (Hall et al, 2007). The WMO mole fraction scales are propagated from the Global Monitoring Division (GMD) of the National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory, which serves as the CCL.…”

“…We have found that the estimated precisions were slightly influenced by a small inhomogeneity in the process of filling each of the 6 sample flasks with gas. It has been reported that the analytical precisions of the conventional methods used at the WMO Central Calibration Laboratory of NOAA/GMD are ∼ 0.02 ppm for CO 2 by an NDIR (Zhao and Tans, 2006), ∼ 1.2 ppb for CH 4 by a GC/FID (Dlugokencky et al, 2005), ∼ 1-2 ppb for CO by a GC/HgO (Novelli et al, 2003), and ∼ 0.12 ppb for N 2 O by a GC/ECD (Hall et al, 2007). Compared with these high-precision methods, our analytical precisions using the laser-based instruments are better by about 2-4 times for CH 4 , CO and N 2 O, although the CO 2 data are slightly variable.…”