Comparison of OSIRIS stratospheric NO2 and O3 measurements with ground-based Fourier transform spectrometer measurements at the Toronto Atmospheric Observatory

Abstract

Stratospheric NO2 and O3 retrieved from measurements of limb-scattered sunlight made by the Optical Spectrograph and InfraRed Imager System (OSIRIS) are compared with like observations made by a ground-based infrared Fourier Transform Spectrometer at the Toronto Atmospheric Observatory (TAO-FTS). Two different versions of OSIRIS NO2 are compared (DOAS version 3.0 and MART version 2.0) with partial column concentrations retrieved from the TAO-FTS. Two OSIRIS O3 versions are also compared (Triplet version 3.0 and MART version 2.0) with O3 retrieved from the TAO-FTS. To accommodate the most coincidences, comparisons are based on monthly mean stratospheric partial columns covering 16–50 km. All coincident monthly means display high correlations: 0.82–0.97. The monthly mean NO2 at TAO compared with the monthly mean NO2 from OSIRIS shows an average difference of less than ~3% with standard deviations up to 6%. The OSIRIS NO2 observations show a multiplicative bias of ~0.8–0.9 and a systematic difference of 5–10% greater then those of the TAO-FTS. O3 differences are less than 5%, on average, with standard deviations ranging from 2% to 2.8%. There is a pronounced multiplicative bias of OSIRIS compared with the TAO-FTS ranging from 0.55 to 0.73. The systematic O3 differences are less than 5% larger for OSIRIS. These small differences meet the standards outlined in the Integrated Global Observing Strategy and confirm the quality of the OSIRIS data for studying stratospheric ozone and nitrogen chemistry.PACS{ 92.60.hd, 92.60.Ry, 92.70.Cp, 93.30.Hf