Validation of NO2 and NO from the Atmospheric Chemistry Experiment (ACE)
Vertical profiles of NO2 and NO have been obtained from solar occultation\nmeasurements by the Atmospheric Chemistry Experiment (ACE), using\nan infrared Fourier Transform Spectrometer (ACE-FTS) and (for NO2)\nan ultraviolet-visible-near-infrared spectrometer, MAESTRO (Measurement\nof Aerosol Extinction in the Stratosphere and Troposphere Retrieved\nby Occultation). In this paper, the quality of the ACE-FTS version\n2.2 NO2 and NO and the MAESTRO version 1.2 NO2 data are assessed\nusing other solar occultation measurements (HALOE, SAGE II, SAGE\nIII, POAM III, SCIAMACHY), stellar occultation measurements (GOMOS),\nlimb measurements (MIPAS, OSIRIS), nadir measurements (SCIAMACHY),\nballoon-borne measurements (SPIRALE, SAOZ) and ground-based measurements\n(UV-VIS, FTIR). Time differences between the comparison measurements\nwere reduced using either a tight coincidence criterion, or where\npossible, chemical box models. ACE-FTS NO2 and NO and the MAESTRO\nNO2 are generally consistent with the correlative data. The ACE-FTS\nand MAESTRO NO2 volume mixing ratio (VMR) profiles agree with the\nprofiles from other satellite data sets to within about 20% between\n25 and 40 km, with the exception of MIPAS ESA (for ACE-FTS) and SAGE\nII (for ACE-FTS (sunrise) and MAESTRO) and suggest a negative bias\nbetween 23 and 40 km of about 10%. MAESTRO reports larger VMR values\nthan the ACE-FTS. In comparisons with HALOE, ACE-FTS NO VMRs typically\n(on average) agree to +/- 8% from 22 to 64 km and to +10% from\n93 to 105 km, with maxima of 21% and 36%, respectively. Partial\ncolumn comparisons for NO2 show that there is quite good agreement\nbetween the ACE instruments and the FTIRs, with a mean difference\nof +7.3% for ACE-FTS and +12.8% for MAESTRO.