Abstract

Abstract. The first three Canadian Arctic ACE validation campaigns were held during polar sunrise at Eureka, Nunavut, Canada (80° N, 86° W) from 2004 to 2006 in support of validation of the ACE (Atmospheric Chemistry Experiment) satellite mission. Three or four zenith-sky viewing UV-visible spectrometers have taken part in each of the three campaigns. The differential slant column densities and vertical column densities of ozone and NO2 from these instruments have been compared following the methods of the UV-visible Working Group of the NDACC (Network for Detection of Atmospheric Composition Change). The instruments are found to partially agree within the required accuracies for both species, although both the vertical and slant column densities are more scattered than required. This might be expected given the spatial and temporal variability of the Arctic stratosphere in spring. The vertical column densities are also compared to integrated total columns from ozonesondes and integrated partial columns from the ACE-FTS (ACE-Fourier Transform Spectrometer) and ACE-MAESTRO (ACE-Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation) instruments on board ACE. For both species, the columns from the ground-based instruments and the ozonesondes are found to generally agree within their combined error bars. The ACE-FTS ozone partial columns and the ground-based total columns agree within 4.5%, averaged over the three campaigns. The ACE-MAESTRO ozone partial columns are generally smaller than those of the ground-based instruments, by an average of 9.9%, and are smaller than the ACE-FTS columns by an average of 14.4%. The ACE-FTS NO2 partial columns are an average of 13.4% smaller than the total columns from the ground-based instruments, as expected. The ACE-MAESTRO NO2 partial columns are larger than the total columns of the ground-based instruments by an average of 2.5% and are larger than the partial columns of the ACE-FTS by an average of 15.5%.

Highlights

  • The first three Canadian Arctic ACE (Atmospheric Chemistry Experiment) validation campaigns were held during polar sunrise at the Polar Environmental Atmospheric Research Laboratory (PEARL), 15 km from Eureka, Nunavut (80◦ N, 86◦ W) from 2004 to 2006

  • The Canadian Arctic ACE validation campaigns were not NDACC intercomparison campaigns, they did meet the requirements of an instrument intercomparison: the measurement site was reasonably free from tropospheric pollution, measurements were made for at least ten days, measurements were taken over the course of the entire day, and the measurements were coincident in time

  • The ozone and NO2 differential slant column densities (DSCDs) and vertical column densities (VCDs) from four UV-visible zenith-sky instruments have been compared following the techniques adopted by the UV-visible Working Group of the NDACC

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Summary

Introduction

The first three Canadian Arctic ACE (Atmospheric Chemistry Experiment) validation campaigns (the “Eureka campaigns”) were held during polar sunrise at the Polar Environmental Atmospheric Research Laboratory (PEARL), 15 km from Eureka, Nunavut (80◦ N, 86◦ W) from 2004 to 2006. Detailed comparisons of the differential slant column densities (DSCDs) and vertical column densities (VCDs) of ozone and NO2 measured by these four instruments have been performed and are discussed . These groundbased measurements are compared to partial columns measured by the ACE-FTS (ACE-Fourier Transform Spectrometer) and ACE-MAESTRO instruments onboard the ACE satellite. In order to maintain the uniformity of measurements made throughout the NDACC, intercomparison campaigns between UVvisible instruments are periodically held. The Canadian Arctic ACE validation campaigns were not NDACC intercomparison campaigns, they did meet the requirements of an instrument intercomparison: the measurement site was reasonably free from tropospheric pollution, measurements were made for at least ten days, measurements were taken over the course of the entire day, and the measurements were coincident in time

Description of the campaigns
Instruments
Differential optical absorption spectroscopy
Derivation of vertical column densities
Comparison methods
Differential slant column density comparisons
Relation to the previous MANTRA 2004 comparison
Comparison of methods
Comparisons between ground-based instruments
Comparisons with satellite instruments
Summary of satellite comparisons
Consideration of meteorological conditions
Findings
Conclusions
Full Text
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