Validation of stratospheric and mesospheric ozone observed by SMILES from International Space Station

[摘要] We observed ozone (O₃) in the verticalregion between 250 and 0.0005 hPa (~ 12–96 km) usingthe Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on theJapanese Experiment Module (JEM) of the International Space Station (ISS)between 12 October 2009 and 21 April 2010. The new 4 Ksuperconducting heterodyne receiver technology of SMILES allowed us toobtain a one order of magnitude better signal-to-noise ratio for theO₃ line observation compared to past spaceborne microwaveinstruments. The non-sun-synchronous orbit of the ISS allowed us to observeO₃ at various local times.We assessed the quality of the vertical profiles of O₃in the 100–0.001 hPa (~ 16–90 km) region for theSMILES NICT Level 2 product version 2.1.5. The evaluation is based on fourcomponents: error analysis; internal comparisons of observations targetingthree different instrumental setups for the same O₃625.371 GHz transition; internal comparisons of two differentretrieval algorithms; and external comparisons for various local times withozonesonde, satellite and balloon observations (ENVISAT/MIPAS,SCISAT/ACE-FTS, Odin/OSIRIS, Odin/SMR, Aura/MLS, TELIS).SMILES O₃data have an estimated absolute accuracy of better than 0.3 ppmv(3%) with a vertical resolution of 3–4 km over the 60 to8 hPa range. The random error for a single measurement is betterthan the estimated systematic error, being less than 1, 2, and7%, in the 40–1, 80–0.1, and100–0.004 hPa pressure regions, respectively.SMILES O₃abundance was 10–20% lower than all other satellite measurements at8–0.1 hPa due to an error arising from uncertainties of the tangentpoint informationand the gain calibration for the intensity of thespectrum.SMILES O₃ from observation frequency Band-B had better accuracy than that from Band-A.A two month period is required toaccumulate measurements covering 24 h in local time of O₃ profile.However such a dataset can also contain variation due to dynamical, seasonal, and latitudinaleffects.

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