Four Fourier transform spectrometers and the Arctic polar vortex: instrument intercomparison and ACE-FTS validation at Eureka during the IPY springs of 2007 and 2008

Abstract

Bruker 125HR are shown to agree to within 3.5% with the existing Environment Canada Bomem DA8 measurements. After smoothing both of these sets of measurements to account for the lower spectral resolution of the University of Waterloo Portable Atmospheric Research Interferometric Spectrometer for the Infrared (PARIS-IR), the measurements were likewise shown to agree with PARIS-IR to within 7%. Concurrent measurements of these gases were also made with the satellite-based Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) during overpasses of Eureka during these time periods. While one of the mandates of the ACE satellite mission is to study ozone depletion in the polar spring, previous validation exercises have identified the highly variable polar vortex conditions of the spring period to be a challenge for validation efforts. In this Correspondence to: R. L. Batchelor (rbatchelor@atmosp.physics.utoronto.ca) work, comparisons between the CANDAC Bruker 125HR and ACE-FTS have been used to develop strict criteria that allow the ground-and satellite-based instruments to be confidently compared. When these criteria are taken into consideration, the observed biases between the ACE-FTS and ground-based FTIR spectrometer are not persistent for both years and are generally insignificant, though small positive biases of ∼5%, comparable in magnitude to those seen in previous validation exercises, are observed for HCl and HF in 2007, and negative biases of −15.3%, −4.8% and −1.5% are seen for ClONO 2 , HNO 3 and O 3 in 2008.

Intercomparison of atmospheric water vapour measurements at a Canadian High Arctic site

“…PEARL is strategically located for Arctic studies, as well as the validation of satellite measurements (e.g. Batchelor et al, 2010;Adams et al, 2012). Validating the accuracy of PEARL water vapour measurements thus has substantial value.…”

Multi-year comparisons of ground-based and space-borne Fourier transform spectrometers in the high Arctic between 2006 and 2013

“…The inclusion of criteria ensuring that similar air masses are sampled with respect to the polar vortex reduces this difference seen in the Arctic significantly. Using these additional criteria, Batchelor et al (2010) and Fu et al (2011) found much improved mean differences, between the ACE-FTS (v2.2+updates) and ground-based FTS datasets, for O 3 , HCl, HNO 3 , and HF comparisons by approximately a factor of 2. These mean differences are comparable to the typical differences at lower latitudes.…”

“…All of these trace gases are routinely derived from the Bruker 125HR spectra and have been used in numerous studies (e.g., Batchelor et al, 2009;Lindenmaier et al, 2010Lindenmaier et al, , 2011Viatte et al, 2014;Holl et al, 2016). Retrievals of O 3 , HCl, HNO 3 , HF, N 2 O, CO, and C 2 H 6 from PARIS-IR's spectra have also been published and compared to other instruments in previous studies (e.g., Sung et al, 2007;Wunch et al, 2007;Batchelor et al, 2010;Fu et al, 2011;Griffin et al, 2013;Franco et al, 2016). The PARIS-IR CH 4 columns are presented for the first time in this study.…”

“…ACE-FTS started routine measurements in February 2004, followed quickly by the first of the Canadian Arctic ACE validation campaigns which continue to this day. These campaigns (e.g., Kerzenmacher et al, 2005;Fraser et al, 2008;Batchelor et al, 2010;Fu et al, 2011;Adams et al, 2012) comprise groundbased measurements during the polar sunrise period (from the end of February to early April) at the Polar Environment Atmospheric Research Laboratory (PEARL) near Eureka, Nunavut (Fogal et al, 2013), at approximately 80 • N, 86 • W. Two ground-based Fourier transform spectrometers (FTSs), the Portable Atmospheric Research Interferometric Spectrometer for the InfraRed (PARIS-IR), and the highresolution Bruker 125HR FTS are part of these campaigns. Here, these datasets are used to compare multiple trace gas species to the space-borne ACE-FTS v3.5 retrievals between 2006.…”

“…For the first time, the stability of the ACE-FTS dataset is examined over an 8-year time period. For these comparisons, we will use the same method and criteria for the viewing geometry as Batchelor et al (2010) and Fu et al (2011), which have been shown to improve the comparison between ground-and satellite-based instruments in the Arctic. Also, the interannual variability of the eight trace gases is discussed and changes in the trace gas columns near Eureka are investigated between 2006 and 2013.…”