Intercomparison of ground-based ozone and NO₂ measurements during the MANTRA 2004 campaign

The MANTRA (Middle Atmosphere Nitrogen TRend Assessment) 2004 campaign took place in Vanscoy, Saskatchewan, Canada (52 N, 107 W) from 3 August to 15 Septem- ber, 2004. In support of the main balloon launch, a suite of five zenith-sky and direct- Sun-viewing UV-visible ground-based spectrometers was deployed, primarily measur- 5 ing ozone and NO2 total columns. Three Fourier transform spectrometers (FTSs) that were part of the balloon payload also performed ground-based measurements of sev- eral species, including ozone. Ground-based measurements of ozone and NO2 di er- ential slant column densities from the zenith-viewing UV-visible instruments are pre- sented herein. They are found to partially agree within NDACC (Network for the Detec- 10 tion of Atmospheric Composition Change) standards for instruments certified for pro- cess studies and satellite validation. Vertical column densities of ozone from the zenith- sky UV-visible instruments, the FTSs, a Brewer spectrophotometer, and ozonesondes are compared, and found to agree within the combined error estimates of the instru- ments (15%). NO2 vertical column densities from two of the UV-visible instruments are 15