Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) - Middle Atmospheric Observations from the International Space Station Masato Shiotani Kyoto University, Kyoto, Japan) and SMILES Mission Team JEM/SMILES Mission The Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) was developed to be aboard the Japanese Experiment Module (JEM) on the International Space Station (ISS). It is a cooperative project of the Japan Aerospace Exploration Agency (JAXA) and the National Institute of Information and Communications Technology (NICT). The key concept of the SMILES is its high-sensitivity measurement of minor species in the middle atmosphere by a receiver using superconductor-insulator-superconductor (SIS) mixers which are cooled to 4.5 K by a mechanical cryocooler (Photo 1). SMILES was successfully launched by the H-IIB rocket with the H-II Transfer Vehicle (HTV; Photo 2) on September 11, 2009, was attached to JEM on September 25, and started atmospheric observations on October 12 (Photo 3). Unfortunately, SMILES observations had been suspended since April 21, 2010 due to the failure of a critical component in the submillimeter local oscillator. Furthermore, the cooler stopped its operation due to the failure of the JEM thermal control system on June 5, Finally, JAXA officially announced its termination of the normal operation on Jan 19, 2011, though the data processing is still continuing. The mission objectives are as follows: i) To demonstrate a 4-K mechanical cooler and superconducting mixers in the environment of outer space for submillimeter limb-emission sounding in the frequency bands of GHz and GHz and ii) To measure atmospheric minor constituents in the middle atmosphere globally (O 3, HCl, ClO, HO 2, HOCl, BrO, O 3 isotopes, HNO 3, CH 3 CN, etc.) in order to get a better understanding of factors and processes controlling the stratospheric ozone amounts and those related to climate change. Comparisons with other data sources Here we compare the SMILES level 2 products version 2.0 with coincident observations from other data sources (such as ACE-FTS, Aura/MLS, Odin/SMR, MIPAS, TIMED/SABER and CCM results from SD-WACCM) for O 3 (Figure 2), HCl (Figure 3), and ClO (Figures 4 and 5). The SMILES O 3 shows an excellent agreement with respect to MLS. However, it has negative bias to ACE and positive bias to WACCM above 50 km. The SMILES HCl matches well with WACCM, though MLS and ACE-FTS above 40 km has a positive bias. The almost constant values above 50 km suggest that SMILES would be better. The SMILES ClO is in good agreement with MLS and WACCM within 10% difference at around 25 to 40 km, but it shows positive bias to WACCM above 40 km. Diurnal variations As SMILES observations cover different local times, we can investigate diurnal cycles for minor species. Figure 6 is for ClO, and Figure 7 is for BrO. P1.22 Aura/MLSJEM/SMILES WACCM ClO [ppb] MLS ClO [ppb] SMILES ClO [ppb] WACCM ClO [ppb] MLS ClO [ppb] SMILES ClO [ppb] WACCM ClO [ppb] Summary Though the observation period is limited for a half year, SMILES provided high-sensitivity measurements of the middle atmosphere minor constituents. The SMILES data are in good agreement with other satellite observations. It is also noteworthy that the SMILES and SD-WACCM outputs indicate mutual consistency with each other, suggesting reasonable performance for these two. One important message is about the upper limit of HCl amounts around the stratopause level; SMILES observations show the mixing ratios around ppb (Figure 8). Based on these observations, day and night time distributions for Cl related species, for example, can be estimated (Figure 9). These results demonstrate SMILES abilities to observe the middle atmospheric minor. Acknowledgements: We appreciate the Aura/MLS, SciSat-1/ACE-FTS, Odin/SMR, MIPAS, and TIMED/SABER mission teams and D. Kinnison (NCAR) for SD-WACCM to provide the data which we used for comparisons. HTV SMILES Measurements SMILES measurements are characterized as follows: i) High sensitivity in detecting atmospheric limb emission of the submillimeter wave range (Band- A ： GHz, Band-B ： GHz, Band-C ： GHz; Figure 1), ii) Vertical profiling (about 3km resolution) from ISS with latitudinal coverage of 65N to 38S; 53 sec for one sequence, about 100 points per one orbit, and about 1600 points per day, and iii) Observing the atmosphere at different local times because of the non-sun-synchronous ISS orbit. O3O3 H 37 Cl HOCl O 3(v1,3) O 3(v2) 18 OOO HNO 3 O3O3 HOCl BrO CH 3 CN O3O3 H 35 Cl O 3(v2) HO 2 O 17 OO 18 OOO O 3(v1,3) O 3(v2) ClO 17 OOO HO 2 O 3(v1,3+v2) 18 OOO HNO 3 BrO O 3(v1,3+v2) 17 OOO Brightness Temp. 20 km 30 km 40 km Figure 1 An example of spectra during the day-time for the three bands at 20, 30, and 40 km. Observed spectra are in thin lines and fitted ones are in thick lines. Band A Band C Band B Photo 1 (left) Mechanical cooler Photo 2 (center) H-II Transfer Vehicle Photo 3 (right) SMILES on JEM To see high sensitivity of SMILES clearly, we have plotted scatter diagrams between SD-WACCM and MLS, and SD- WACCM and SMILES (Figure 5). The agreement with SD-WACCM is better for SMILES than for MLS, and variability of SMILES is much smaller than MLS. Thus, we may also conclude that SD-WACCM performs very well. Figure 5 Scatter plots between SD-WACCM and MLS, and SD-WACCM and SMILES (upper) at 22 km for ClO in day-time and (lower) at 43 km for ClO in night-time. Figure 4 Comparisons of ClO in profiles. SD-WACCM Figure 3 Comparisons of HCl in profiles and in latitude-height sections. Figure 2 Comparisons of O 3 in profiles and in latitude-height sections. Figure 7 Diurnal cycle in BrO at 40 km, and at 13:00. Figure 6 Diurnal cycle in ClO at 10S-10N and at 37 km. SMILES Figure 8 (left) HCl trend around the stratopause level; SMILES observation overlaid on Froidevaux et al. (2006; updated) Figure 9 (right) Day and night vertical distributions for Cl related species