Kazuo Shibasaki

Comparison of ILAS and MkIV profiles of atmospheric trace gases measured above Alaska in May 1997

[1]xa0Vertical profiles of the gases O3, HNO3, NO2, N2O, H2O, and CH4, measured above Fairbanks, Alaska, during a May 1997 balloon flight of the JPL MkIV interferometer are compared with version 5.20 profiles measured by the ILAS instrument on board the ADEOS satellite. Both the ILAS and MkIV instruments employ the solar occultation technique, and for many of these gases, use the same absorption bands in their analyses. The results show good agreement for nearly all of these gases, after taking into account the slight differences in the potential vorticities of the sampled air masses and considering the error bars on the measurements.

Sensitivity studies on sulfur dioxide measurements with satellite-borne solar backscattered ultraviolet spectrometer

The Ozone and Pollution measuring Ultraviolet Spectrometer (OPUS) is scheduled to launch on board the GCOM A1 satellite, to measure ozone, sulfur dioxide (SO2), nitrogen dioxide (NO2) and other chemical species including aerosols. OPUS measures the backscattered ultraviolet radiance with the wavelength step of 0.5 nm in ultraviolet-near infrared regions. This wavelength step is coarse compared with that of GOME, but it was found that this difference do not substantially affect the uncertainty in SO2 estimation. Simulation study using the radiative transfer code of MODTRAN reveals that the wavelength range of 310 - 320 nm was found to be sensitive for SO2 detection in case of solar backscattered radiation measurements from space. We will present the estimation method of total column SO2 amount from the backscattered radiance observed with OPUS, using the fine structure of SO2 absorption spectrum.

Specifications of GCOM-A1/ODUS

UV spectrometers onboard satellites have provided trend data of total O3 for more than two decades. These data have shown the validity of satellite measurements. However, for next-generation observation and to monitor the recent O3 depletion accurately, a high-fidelity spectrometer with high signal to noise ratio (SNR) is essential. For this purpose, the Ozone Dynamics UV Spectrometer (ODUS) has been designed to have higher spectral and spatial resolutions and wide spectral range. It will be launched on the Global Change Observation Mission (GCOM)-A1 satellite in 2006. ODUS covers back- scattered light from 306 to 420 nm with 0.5 nm spectral and 20 km spatial resolutions using a Fastie-Ebert type polychromator and a one-dimensional UV Si-CMOS array detector. The array detector is designed and manufactured specially for ODUS. It has different size pixels and 234 on-chip CMOS amplifiers, which are tuned for each spectral radiance level. ODUS is a nadir-look mapping spectrometer with a mechanical scatter, which can acquire global data in one day. It is expected to provide information about total O3, SO2, NO2, BrO, OClO, H2CO, surface albedo, and aerosol.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Requirement definition study for GCOM-A1/ODUS instrument

This paper defines scientific requirements for the Ozone Dynamics Ultraviolet Spectrometer (ODUS). ODUS is a cross- track scanning spectrometer like Total Ozone Mapping Spectrometer (TOMS) developed by NASA. This instrument is planned to be flown on the Global Change Observation Mission (GCOM)-A1 satellite. ODUS measures solar ultraviolet radiation backscattered from the Earths atmosphere. This study examines the necessity and feasibility of retrieval algorithms for total ozone, volcanic sulphur dioxide (SO2), nitrogen dioxide (NO2) and several other constituents related to ozone chemistry and summarizes requirement definitions for specifications of the ODUS instrument. Finally, we review the conformance of the development policy for retrieval algorithms with the current specifications of the ODUS instrument.

Scientific objectives of GCOM-A1/ODUS

The Ozone Dynamics Ultraviolet Spectrometer (ODUS) is one of core sensors onboard Global Change Observation Mission (GCOM)- Al satellite. The ODUS is a Fastie-Ebert type polychromator which measures the solar ultraviolet radiation of 306 nm to 420 nm wavelength region scattered from the Earths atmosphere and surface. The measuring spectral region contains many absorption features by atmospheric minor constituents such as ozone (O3), sulfur dioxide (SO2), nitrogen dioxide (NO2), and so on. The primary objective of ODUS is to monitor the global total ozone field with an accuracy of 5% before calibration and 2% after calibration. It will map the global total ozone field, except of the latitudinal zone larger than 80 degrees, in one day with better spatial resolution of 20 km by 20 km at nadir than TOMS of 40 km by 40 km. The better spatial resolution will help studying the dynamically related phenomena, such as development of biomass burnings, spreading of urban pollution and of volcanic aerosols, in more detail. In this paper scientific objectives of GCOM A1/ODUS will be discussed and presented.

Trade-off studies on ODUS spectrograph design

ODUS (Ozone Dynamics Ultraviolet Spectrometer) on the GCOM (Global Change Observation Mission)-A1 mission will measure the ozone, SO2, NO2 and other trace constituents both in the stratosphere and in the troposphere through the backscatter ultraviolet (BUV) technique from 306 nm to 420 nm. In the present paper, the design concepts of the ODUS were clarified and a trade-off study among various spectrometer types was done. Since GCOM-A1 will have a non-sun-synchronous orbit, the thermal condition during a recurrent cycle will be more variable than that of a sun-synchronous orbit. Therefore, misalignment caused by thermal stress distortion was expected to be the most critical matter. As a result, a simple conventional Ebert type spectrometer was employed. However astigmatism is a matter of serious concern for the Ebert type spectrometer, because it leads to a significant loss of the input photon flux caused by the image extension of the entrance slit in the direction of detector height. The optimal slit height was determined by the trade-off study between high throughput and the image distortion due to astigmatism. As a detector, a linear photodiode array was employed for ODUS. As the detector is custom made, the shape and the arrangement of each photodiode pixel can be modified by changing the mask design. We optimized the detector height for each photodiode pixel to maximize the SN ratio by calculating the instrument function. According to the above process, the detector was newly fabricated with a dramatic change of the mask design. The new detector was combined with the previously fabricated laboratory model spectrometer. We successfully obtained atmospheric scatter data on the ground with a signal to noise ratio of 350 at the wavelength of around 400 nm.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Overview of GCOM-A1/ODUS program

Global Change Observation Mission (GCOM) is a new generation of earth observation program by NASDA. GCOM aims to derive trends in climate system by long term and systematic measurements of atmosphere, ocean, and land. GCOM-A1 is one of the first generation of GCOM satellites to be launched in 2006, which was formerly called ADEOS-3A. GCOM-A1 will carry atmospheric instruments; two Japanese, Ozone Dynamics Ultraviolet Spectrometer (ODUS), and Solar Occultation Fourier transform spectrometer from Inclined Satellite (SOFIS), and one foreign atmospheric instrument and a GPS occultation instrument.

Plan for the development of retrieval algorithm and ground segment of JEM/SMILES

Superconducting sub-millimeter-wave limb-emission sounder (SMILES) using 4K Superconductor-Insulator-Superconductor (SIS) detector for ISS/JEM is under development. Spectrum of 600 GHz regions will be acquired using acousto-optics spectrometer (AOS). The high sensitivity of SMILES will enable us to measure O3, ClO without enhancement, BrO, Hcl, HO2, HNO3 from 10 to 60 km. This paper describes a current plan of data retrieval algorithms (L0, L1, L2 and L3), ground data system, data validation and data distribution.

Conceptual design of the Ozone Dynamics Ultraviolet Spectrometer (ODUS) on the Global Change Observation Mission (GCOM)-A1 satellite

The Ozone Dynamics Ultraviolet Spectrometer (ODUS) is a satellite-borne, nadir-looking ultraviolet spectrometer for measuring total ozone amount. It will be launched in 2006 onboard Japanese earth observation satellite GCOM-A1 (GCOM : Global Change Observation Mission). The ODUS instrument measures continuous spectrum from 306 to 420nm with 0.5nm spectral step and 20km spatial resolution, using an Ebert-type polychromator and an one-dimensional silicon CMOS array detector, which will improve the accuracy of the retrieved total ozone amount. This paper presents an overview of the ODUS instrument and performance.

Atmospheric composition measurement from the Ozone Dynamics UV Spectrometer (ODUS)

Atmospheric composition measurements from satellites are essential for monitoring the earth’s environment. The Ozone Dynamics UV Spectrometer (ODUS) will be launched on the Global Change Observation Mission (GCOM) -A1 satellite in 2006. ODUS covers from 306 to 420 nm back scattered light with 0.5 nm spectral and 20 km spatial resolution using a Fastie-Ebert type polychromator and a one-dimensional UV Si-CMOS array detector. It is a nadir-looking mapping spectrometer with a mechanical scanner, which can acquire global data in one day. It is expected to provide information about total O3, SO2, NO2, BrO, OCIO, HCHO, surface albedo, and aerosol type. Total 03 is inferred from look-up tables calculated with the radiative transfer on multiple solar back scattering. Other constituents are derived in such a way that the deviation of the measured and calculated radiance is minimized. We use the STAR (System for Transfer of Atmospheric Radiation) code for radiative transfer calculation. In recent years, tropospheric O3 measurement has become important for biomass burning and urban air pollution monitoring. The sensitivity of various O3 vertical profiles on the ODUS spectra is studied and tropospheric O3 retrieval algorithm will be presented.