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

Abstract

We observed the diurnal variation of ozone (O₃) in the vertical region between 250 and 0.0005 hPa (~12–96 km) using the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) on the Japanese Experiment Module (JEM) of the International Space Station (ISS) between 12 October 2009 and 21 April 2010. The new 4 K superconducting heterodyne receiver technology of SMILES allowed us to obtain a one order of magnitude better signal-to-noise ratio for the O₃ line observation compared to past spaceborne microwave instruments. We assessed the quality of the vertical profiles of O₃ in the 100–0.001 hP (~16–90 km) region for the SMILES NICT Level 2 product version 2.1.5. The evaluation is based on four components; error analysis; internal comparisons of observations targeting three different instrumental setups for the same O₃ 625.371 GHz transition; internal comparisons of two different retrieval algorithms; and external comparisons for various local times with ozonesonde, satellite and balloon observations (ENVISAT/MIPAS, SCISAT/ACE-FTS, Odin/OSIRIS, Odin/SMR, Aura/MLS, TELIS). SMILES O₃ data have an estimated absolute accuracy of better than 0.3 ppmv (3%) with a vertical resolution of 3–4 km over the 60 to 8 hPa range. The random error for a single measurement is better than the estimated systematic error, being less than 1, 2, and 7%, in the 40–1, 80–0.1, and 100–0.004 hPa pressure region, respectively. SMILES O₃ abundance was 10–20% lower than all other satellite measurements at 8–0.1 hPa due to an error arising from uncertainties of the tangent point information and the calibration problem for the intensity of the spectrum. The non sun-synchronous orbit of the ISS allowed us to observe O₃ at various local times. A two month period is required to accumulate measurements covering 24 h in local time. However such a dataset can also contain variation due to dynamical, seasonal, and latitudinal effects

Observation of horizontal winds in the middle-atmosphere between 30° S and 55° N during the northern winter 2009–2010

“…It observed the Earth's limb, scanning from −7 to 100 km in 53 s, providing 1600 spectral radiance profiles per day. Using Superconductor-InsulatorSuperconductor (SIS) detectors cooled at 4 K, it provided high quality spectra allowing constituent profiles of many species such as ozone (O 3 ) and hydrogen chloride (HCl) to be derived (Kasai et al, 2006;Takahashi et al, 2010;Khosravi et al, 2012;Kasai et al, 2013). SMILES observed spectral lines from the atmospheric limb in three frequency bands, named A (624.3-625.5 GHz), B (625.1-626.3 GHz) and C (649.1-650.3 GHz) but only two are measured simultaneously.…”

“…The actual mean precision of the winds derived from O 3 is likely between 12-15 m s −1 . Above 70 km (0.05 hPa), ozone has strong diurnal and latitudinal variations (Kasai et al, 2013) which induce large variations of the O 3 line intensity of more than an order of magnitude, and therefore, of the wind retrieval precision.…”

Performance Assessment of Balloon-Borne Trace Gas Sounding with the Terahertz Channel of TELIS

“…The corresponding data processing algorithms were described in [82]. Although the operation period of the SMILES instrument was shorter than expected due to the failure of the submillimeter local oscillator, the retrieval products of ozone and chlorine species have been validated against other ozonesonde, satellite, and balloon observations [32,90]. During the TELIS/MIPAS-B 2010 flight, SMILES was still active and its ozone observations are available for our comparisons.…”

“…During the TELIS/MIPAS-B 2010 flight, SMILES was still active and its ozone observations are available for our comparisons. The error analysis in [32] shows that in the stratosphere, the retrieval error is dominated by systematic effects (∼ 3-8%), with a vertical resolution of 3-6 km.…”

“…After a test flight in 2008 in Teresina, Brazil, the TELIS instrument participated in three scientific campaigns on 11 March 2009, 24 January 2010, and 31 March 2011, respectively. The balloon was launched from Kiruna, Sweden and landed after about 12-14 h. These three winter flights are particularly important for validating coincident spaceborne observations, for instance TELIS for SMILES/JEM and MLS/Aura [25,32], and MIPAS-B for MIPAS/Envisat [33]. The latest joint balloon campaign took place on 7 September 2014 over Ontario, Canada.…”