KEYWORDS: Signal to noise ratio, Sensors, Signal processing, Satellites, Digital signal processing, Design and modelling, Image processing, Process control, Spectroscopy, Quantum efficiency
Regarding crop production, which is the basis for food security, improving yields, using fewer materials through the appropriate use of nitrogen fertilizers and pesticides, and protecting the environment have become important global issues. This is part of the Green Food System Strategy announced by Japan's Ministry of Agriculture, Forestry, and Fisheries (MAFF) in May 2021. In this context, we plan to launch a miniature satellite with a hyperspectral sensor to observe Canopy Nitrogen Content (CNC) and Solar-Induced Fluorescence (SIF) in the mid-to the late 2020s. A miniature hyper spectrometer with a wide spectral range of 400 nm to 1700 nm and a narrow spectral resolution of 2nm to 10 nm, with a relatively medium Ground Sampling Distance (GSD) of 70m and Signal-to-Noise Ratio (SNR) of approximately 130 is currently under consideration. System optimization, such as the trade-off between the GSD and SNR under mass and envelope constraints, and the introduction of cutting-edge technologies, such as visible-enhanced InGaAs detectors, are both critical to the realization of specific mission objectives. A feasibility study and preliminary payload design are presented in this thesis.
New level 2 products v2.0 of JEM/SMILES are scheduled to be released in Sep., 2011. This will be the first publicreleased
version. In pre-released product v1.3, positive bias of retrieved temperature in the stratosphere was the largest
issue since temperature is basic parameter which characterizes the atmospheric structure. The new product use latest L1B
007 which includes gain nonlinearity effect of receivers, bias of temperature in upper stratosphere is suppressed. In
addition, we stopped temperature retrieval above 40km and refer MLS temperature product with applying migrating tidal
model. HCl profiles in mesosphere become constant, which supports this temperature processing.
The Superconducting submillimeter-wave limb-emission sounder (SMILES) employs superconducting detectors
mechanically cooled down to ~4K, and it is extremely sensitive (Tsys < 400K), for the weak emission from trace species
of stratosphere and mesosphere, such as O3, HCl, HNO3, ClO, HO2, and BrO. SMILES was launched onboard HTV
spacecraft by using H-IIB launcher and started atmospheric observation in autumn of 2009. Using 2 bands among 3
bands in the 625 and 650 GHz submillimeter region, SMILES has been observing precise spectra with ~1K noise. Level-
2 (L2) data processing is on going at ISAS/JAXA in semi-real time basis. O3, HCl, HNO3 and ClO have strong emission
signal in the SMILES frequency coverage and we already found that SMILES L2 data is comparable or even better than
the existing best satellite observation of the atmosphere. HO2 and BrO have been retrieved with single scan data
successfully and the results are under verification. Since SMILES observation is much better than any previous
observation, validation of SMILES L2 data will be challenging. This paper describes L2 processing at ISAS/JAXA and
early results of SMILES.
Air-OPUS is a hyper spectral imaging spectrograph, with 0.34 nm spectral step, 190-455 nm spectral coverage, and 330 spatial channels covering 15 degrees field of view (FOV). It is designed as an airborne instrument for the demonstration of spaceborne-OPUS. After two-demonstration campaign using the Gulfstream-II aircraft, the performances of AIR-OPUS, such as spectral resolution, signal-to-noise ration (SNR) have been evaluated. It is concluded that the performances have agreed with designed value. This paper describes design, the performance, and the first results of Air-OPUS. Concept of next generation Air-OPUS, with wider FOV and visible/near-IR spectral coverage, will be also briefly presented.
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.
An FTS instrument is proposed for a part of active and passive sensor combination of the EarthCARE mission, jointly proposed to the 2nd ESA earth explorer selection. The FTS will be a compact 4-ports dual pendulum design with 0.5 cm-1 spectral resolution to cover 400-2000 cm-1 region. The IFOV is 10 by 10 km square to coincide with other passive instruments, and the observation is contiguous which is required for the EarthCARE.
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.
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.
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.
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 Earth's 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.
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 Earth's 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.
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.
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.
The Ozone Dynamics Ultraviolet Spectrometer (ODUS) is a satellite-borne, nadir-looking ultraviolet spectrometer for measuring total ozone amount. It will be launched in 2005 onboard Japanese earth observation satellite GCOM-A1. The ODUS instrument measures continuous spectrum from 306 to 420 nm with 0.5 nm spectral resolution and 20 km spatial resolution, using an Ebert-type polychromator and a one-dimensional silicon CMOS array detector, which will improve the accuracy of the retrieved total ozone amount. We have completed the conceptual design of system, and manufactured and tested the laboratory model of the detector and the optical assembly. We have succeeded in developing a detector with sufficient sensitivity and a polychromator with little stray light. We have also confirmed the optical performance and evaluated the detailed wavelength structure of the instrument function. This paper presents an overview of the ODUS instrument, the summary of the evaluation results of the laboratory models.
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