Simultaneous atmospheric measurements using two Fourier transform infrared spectrometers at the Polar Environment Atmospheric Research Laboratory during spring 2006, and comparisons with the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer

Abstract

The 2006 Canadian Arctic ACE (Atmospheric Chemistry Experiment) Validation Campaign collected measurements at the Polar Environment Atmospheric Research Laboratory (PEARL, 80.05 degree N, 86.42 degree W, 610 m above sea level) at Eureka, Canada from 17 February to 31 March 2006. Two of the ten instruments involved in the campaign, both Fourier transform spectrometers (FTSs), were operated simultaneously, recording atmospheric solar absorption spectra. The first instrument was an ABB Bomem DA8 high-resolution infrared FTS. The second instrument was the Portable Atmospheric Research Interferometric Spectrometer for the Infrared (PARIS-IR), the ground-based version of the satellite-borne FTS on the ACE satellite (ACE-FTS). From the measurements collected by these two ground-based instruments, total column densities of seven stratospheric trace gases (O sub(3), HNO sub(3), NO sub(2), HCl, HF, NO, and ClONO sub(2) were retrieved using the optimal estimation method and these results were compared. Since the two instruments sampled the same portions of atmosphere by synchronizing observations during the campaign, the biases in retrieved columns from the two spectrometers represent the instrumental differences. These differences were consistent with those seen in previous FTS intercomparison studies. Partial column results from the ground-based spectrometers were also compared with partial columns derived from ACE-FTS version 2.2 (including updates for O sub(3), HDO and N sub(2)O sub(5) profiles and the differences found were consistent with the other validation comparison studies for the ACE-FTS version 2.2 data products. Column densities of O sub(3), HCl, ClONO sub(2), and HNO sub(3) from the three FTSs were normalized with respect to HF and used to probe the time evolution of the chemical constituents in the atmosphere over Eureka during spring 2006.