Updated validation of ACE and OSIRIS ozone and NO2 measurements in the Arctic using ground-based instruments at Eureka, Canada

This paper presents long-term intercomparisons (2003-2017) between ozone and NO2 measured by the Optical Spectrograph and Infra-Red Imager System (OSIRIS) and the Atmospheric Chemistry Experiment (ACE) satellite instruments, and by ground-based instruments at the Polar Environment Atmospheric Research Laboratory (PEARL), near Eureka, Nunavut, Canada (80 degrees N, 86 degrees W). The ground-based instruments include four zenith-sky differential optical absorption spectroscopy (DOAS) instruments, two Fourier transform infrared (FTIR) spectrometers, and a Brewer spectrophotometer. Comparisons of 14-52 km ozone partial columns show good agreement between OSIRIS v5.10 and ACE-FTS v3.5/3.6 data (1.2%), while ACE-MAESTRO v3.13 ozone is smaller than the other two datasets by 6.7% and 5.9%, respectively. Satellite profiles were extended to the surface using ozonesonde data, and the resulting columns agree with the ground-based datasets with mean relative differences of 0.1-12.0%. For NO2, 12-40 km partial columns from ACE-FTS v3.5/3.6 and 12-32 km partial columns from OSIRIS v6.0 (scaled to 40 km) agree with ground-based partial columns with mean relative differences of 0.7-33.2%. Dynamical coincidence criteria improved the ACE to ground-based FTIR ozone comparisons, while little to no improvements were seen for other instruments, and for NO2. A +/- 1 degrees latitude criterion modestly improved the spring and fall NO2 comparisons. The results of this study are consistent with previous validation exercises. In addition, there are no significant drifts between the satellite datasets, or between the satellites and the ground-based measurements, indicating that the OSIRIS and ACE instruments continue to perform well. (C) 2019 The Authors. Published by Elsevier Ltd.