Intercomparison of NDSC Ground-Based Solar FTIR Measurements of Atmospheric Gases at Lauder, New Zealand

Abstract

A formal intercomparison of atmospheric total column measurements of N 2 O, N 2 , CH 4 , O 3 , HCl, HNO 3 , and HF by two ground-based solar Fourier transform infrared (FTIR) spectrometers conducted as part of the Network for the Detection of Stratospheric Change (NDSC) instrument certification procedure at Lauder, New Zealand, is presented. The two instruments were nominally very similar, collocated, and collected data at the same times. Collected spectra were analyzed independently by the individual operators in a blind-phase intercomparison, then reanalyzed by a single operator using identical analysis methods to eliminate any potential bias from the spectral analysis. From the consistent reanalysis, gases with predominantly tropospheric distributions and pressure-broadened spectral lines, such as N 2 O and CH 4 , showed differences between retrieved columns of typically less than 1%. For predominantly stratospheric gases, such as HCl and O 3 , differences were less than 3%. In most cases, the differences were greater than the scatter in the individual measurements and were significant at the 95% confidence level. The worst case observed was for HF, which showed a 7% systematic bias between instruments. The differences are consistent in magnitude with those expected for known types of imperfection in spectrometer alignment and operation, but attempts to quantify these effects through instrument line shape analysis, phase error, zero offsets, and channel spectra did not remove the apparent differences.

Retrieval of ammonia from ground-based FTIR solar spectra

“…The maximum concentrations occur around April, which is consistent with temporal emission patterns for manure application reported for this region (Friedrich and Reis, 2004;Van Damme et al, 2015b;Paulot et al, 2014). The baseline variability with higher concentrations in summer can be explained by an increase in volatilization rates of NH 3 , emitted from livestock housing, which is driven by animal activity and temperature (Gyldenkaerne et al, 2005). A comparison is made with CO to distinguish between agricultural and fire emissions sources.…”

Evaluation of the inter-annual variability of stratospheric chemical composition in chemistry-climate models using ground-based multi species time series

“…The quality of SAOZ data has been evaluated during several instrument intercomparisons (Hofmann et al, 1994;Roscoe et al, 1999;Hendrick et al, 2011). The FT-IR measurements have also been validated by many instrument intercomparisons and by comparison with satellite observations (Lambert et al, 2003;Griffith et al, 2003;Hauchecorne et al, 2005;Dils et al, 2006;Griesfeller et al, 2006;Vigouroux et al, 2008). The periods of observation vary for different species and stations, and are summarized in Table 1.…”

Simultaneous ground-based observations of O<sub>3</sub>, HCl, N<sub>2</sub>O, and CH<sub>4</sub> over Toronto, Canada by three Fourier transform spectrometers with different resolutions

“…The five microwindows used in this campaign are listed in Table 2. Two microwindows for ozone (near 3040 cm −1 and 2775 cm −1 ) were chosen because they yielded the highest degrees of freedom for signal for the lower resolution instruments in the spectral range considered, compared with the more commonly used 3045 cm −1 microwindow (e.g., Goldman et al, 1999;Griffith et al, the interest of consistency, retrievals of ozone are considered only in the spectral ranges measured by all three instruments.…”