Validation of NO 2 and NO from the Atmospheric Chemistry Experiment (ACE)

Abstract

Vertical profiles of NO 2 and NO have beenobtained from solar occultation measurements by theAtmospheric Chemistry Experiment (ACE), using aninfrared Fourier Transform Spectrometer (ACE-FTS)and (for NO 2) anultraviolet-visible-near-infrared spectrometer,MAESTRO (Measurement of Aerosol Extinction in theStratosphere and Troposphere Retrieved byOccultation). In this paper, the quality of theACE-FTS version 2.2 NO 2 and NO and theMAESTRO version 1.2 NO 2 data are assessedusing other solar occultation measurements (HALOE,SAGE II, SAGE III, POAM III, SCIAMACHY), stellaroccultation measurements (GOMOS), limb measurements(MIPAS, OSIRIS), nadir measurements (SCIAMACHY),balloon-borne measurements (SPIRALE, SAOZ) andground-based measurements (UV-VIS, FTIR). Timedifferences between the comparison measurements werereduced using either a tight coincidence criterion,or where possible, chemical box models. ACE-FTSNO 2 and NO and the MAESTRO NO 2 are generally consistent with the correlativedata. The ACE-FTS and MAESTRO NO 2 volumemixing ratio (VMR) profiles agree with the profilesfrom other satellite data sets to within about 20%between 25 and 40 km, with the exception of MIPASESA (for ACE-FTS) and SAGE II (for ACE-FTS (sunrise)and MAESTRO) and suggest a negative bias between 23and 40 km of about 10%. MAESTRO reports larger VMRvalues than the ACE-FTS. In comparisons with HALOE,ACE-FTS NO VMRs typically (on average) agree to±8% from 22 to 64 km and to +10% from 93 to105 km, with maxima of 21% and 36%,respectively. Partial column comparisons forNO 2 show that there is quite goodagreement between the ACE instruments and the FTIRs,with a mean difference of +7.3% for ACE-FTS and+12.8% for MAESTRO.