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Akiyoshi H.,Japan National Institute of Environmental Studies | Nakamura T.,Japan National Institute of Environmental Studies | Nakamura T.,Hokkaido University | Nakamura T.,Japan National Institute of Polar Research | And 4 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2016

Stratospheric sudden warming (SSW) is a dramatic phenomenon of the winter stratosphere in which the distribution of chemical constituents, associated chemical tendency, and transport of chemical constituents differ significantly inside and outside of the polar vortex. In this study, the chemical constituent distributions in the major SSW of 2009/2010 were simulated by the Model for Interdisciplinary Research on Climate 3.2-Chemistry-Climate Model (CCM) nudged toward the European Center for Medium-Range Weather Forecasts-Interim Re-Analysis data. The results were compared with Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) and Microwave Limb Sounder (MLS) observations. In addition, ozone tendency due to ozone transport and chemical ozone loss in the high-latitude lower stratosphere before and after the SSW was analyzed for the period from 1 January 2010 to 11 February 2010. The evolution and distribution of ozone and HCl inside/outside the polar vortex associated with the vortex shift to the midlatitudes in January are quite similar between SMILES and MLS. Those of ClO are also similar, considering the difference in the local time for the measurement. Analyses of the nudged CCM run indicate that inside the polar vortex at 50 hPa, the ozone concentration increased moderately owing to partial cancelation between the large negative ozone tendency due to chemical ozone destruction and large positive ozone tendency due to horizontal ozone influx from outside of the vortex as well as downward advection. In the region of a high ozone concentration with the same area as that of the polar vortex at 50 hPa, the large increase in ozone was primarily due to a downward advection of ozone. SMILES and MLS observations, nudged CCM simulations, and ozone tendency analyses revealed a highly longitudinal dependent ozone tendency at high latitudes during the SSW ©2016. American Geophysical Union. All Rights Reserved.

Khosravi M.,Chalmers University of Technology | Baron P.,Japan National Institute of Information and Communications Technology | Urban J.,Chalmers University of Technology | Froidevaux L.,Jet Propulsion Laboratory | And 16 more authors.
Atmospheric Chemistry and Physics | Year: 2013

The diurnal variation of HOCl and the related species ClO, HO2 and HCl measured by satellites has been compared with the results of a one-dimensional photochemical model. The study compares the data from various limb-viewing instruments with model simulations from the middle stratosphere to the lower mesosphere. Data from three sub-millimetre instruments and two infrared spectrometers are used, namely from the Sub-Millimetre Radiometer (SMR) on board Odin, the Microwave Limb Sounder (MLS) on board Aura, the Superconducting Submillimeter-wave Limb-Emission Sounder (SMILES) on the International Space Station, the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on board ENVISAT, and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) on board SCISAT. Inter-comparison of the measurements from instruments on sun-synchronous satellites (SMR, MLS, MIPAS) and measurements from solar occultation instruments (ACE-FTS) is challenging since the measurements correspond to different solar zenith angles (or local times). However, using a model which covers all solar zenith angles and data from the SMILES instrument which measured at all local times over a period of several months provides the possibility to verify the model and to indirectly compare the diurnally variable species. The satellite data were averaged for latitudes of 20 S to 20 N for the SMILES observation period from November 2009 to April 2010 and were compared at three altitudes: 35, 45 and 55 km. Besides presenting the SMILES data, the study also shows a first comparison of the latest MLS data (version 3.3) of HOCl, ClO, and HO2 with other satellite observations, as well as a first evaluation of HO2 observations made by Odin/SMR. The MISU-1D model has been carefully initialised and run for conditions and locations of the observations. The diurnal cycle features for the species investigated here are generally well reproduced by the model. The satellite observations and the model agree well in terms of absolute mixing ratios. The differences between the day and night values of the model are in good agreement with the observations although the amplitude of the HO2 diurnal variation is 10-20% lower in the model than in the observations. In particular, the data offered the opportunity to study the reaction ClO+HO2 → HOCl+O2 in the lower mesosphere at 55 km. At this altitude the HOCl night-time variation depends only on this reaction. The result of this analysis points towards a value of the rate constant within the range of the JPL 2006 recommendation and the upper uncertainty limit of the JPL 2011 recommendation at 55 km.

Aoyama M.,Nanzan University | Nakatani T.,University of Tsukuba | Saito S.,NTT Data | Suzuki M.,TIS | And 3 more authors.
Proceedings - Asia-Pacific Software Engineering Conference, APSEC | Year: 2010

Requirements engineering has been extensively developed as a discipline. Many statistics on the software development indicate requirements process is the most influential to both success and failure of software development. However, practitioners are still difficult to learn and apply requirements engineering. As a guideline for practitioners to learn and apply requirements engineering, we developed REBOK (Requirements Engineering Body Of Knowledge). In the development, we found there is no common model of BOKs in software engineering. This article proposes the model and architecture of the body of knowledge of REBOK and its proof of the concept. © 2010 IEEE.

Imai K.,Japan Aerospace Exploration Agency | Fujiwara M.,Hokkaido University | Inai Y.,Kyoto University | Manago N.,Chiba University | And 8 more authors.
Journal of Geophysical Research: Atmospheres | Year: 2013

We compared ozone profiles measured by the Superconducting Submillimeter-Wave Limb-Emission Sounder (SMILES) with those taken at worldwide ozonesonde stations. To assess the quality of the SMILES version 2.3 ozone data for 16-30 km, 601 ozonesonde profiles were compared with the coincident SMILES ozone profiles. The agreement between SMILES and ozonesonde measurements was generally good within 5%-7% for 18-30 km at middle and high latitudes but degraded below 18 km. At low latitudes, however, the SMILES ozone data showed larger values (∼6%-15% for 20-26 km) than those at middle and high latitudes. To explain this bias, we explored some possible issues in the ozonesonde measurement system. One possibility is due to a pressure bias in radiosonde measurements with a pressure sensor, but it would be within a few percent. We also examined an issue of the ozonesonde's response time. The response time was estimated from ozonesonde measurements with ascending and descending profiles showing clear difference, by using the time lag correction method to minimize the difference between them. Our estimation shows 28 s on average which is a similar value derived by prelaunch preparation. By applying this correction to the original profiles, we found a negative bias of the ascending ozonesonde measurement more than 7% at 20 km in the equatorial latitude where the vertical gradient of ozone is steep. The corrected ozonesonde profiles showed better agreement with the SMILES data. We suggest that the response time of ozonesondes could create a negative bias, particularly in the lower stratosphere at equatorial latitudes. Key Points SMILES ozone profiles are compared with worldwide ozonesondes This study presents the quality of the SMILES ozone product Suggest a possible bias of ozonesonde measurements ©2013. American Geophysical Union. All Rights Reserved.

Ozeki H.,Toho University | Mizobuchi S.,Japan Aerospace Exploration Agency | Tamaki K.,Toho University | Kikuchi K.-I.,Japan National Institute of Information and Communications Technology | And 4 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2011

On-orbit performance of the radio spectrometer of SMILES is discussed. We focused on the telemetry data of photodiode current, laser diode current, and laser diode operating temperature. The data showed degradation trend as the mission went on. This is due to a wear-out phenomenon of commercially available laser diode, which is used as the light source of the radio spectrometer. Since the laser diodes have a certain lifetime, both screening procedure and operating condition for them must be properly defined and implemented for ensuring a good performance of the spectrometer throughout designed mission life. For these purposes, we conducted several kinds of qualification tests including an accelerated life time test during design phase, and expected life time of the laser diode was derived on the basis of these test results. In this paper, the results from the qualification tests at ground and the actual performance on orbit with the telemetry and mission data will be presented. © 2011 SPIE.

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