Hiroshi Suto

Japan Aerospace Exploration Agency, Chōfu, Tokyo, Japan

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Publications (84)62.61 Total impact

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    ABSTRACT: A dataset containing more than six years (February 2009 to present) of radiance-spectra for carbon dioxide (CO2) and methane (CH4) observations has been acquired by the Greenhouse gases Observing SATellite (GOSAT), nicknamed "Ibuki", Thermal And Near infrared Sensor for carbon Observation Fourier-Transform Spectrometer (TANSO-FTS). This manuscript provides updates on the performance of the satellite and TANSO-FTS sensor and describes important changes to the data product, which has recently been made available to users. With these changes the typical accuracy of retrieved column-averaged dry air mole fractions of CO2 and CH4 (XCO2 and XCH4) are 2 ppm or 0.5 % and 13 ppb or 0.7 %, respectively. Three major anomalies of the satellite system affecting TANSO-FTS are reported: a failure of one of the two solar paddles in May 2014, a switch to the secondary pointing system in January 2015 and most recently, a cryo-cooler shutdown and restart in August 2015. The Level 1A (L1A) (raw interferogram) and the Level 1B (L1B) (radiance spectra) of version V201.201 (V201) described here have long-term uniform quality and provide consistent retrieval accuracy even after the satellite system anomalies. In addition, we discuss the unique observation abilities of GOSAT, made possible by an agile pointing mechanism, which allows for optimization of global sampling patterns.
    Preview · Article · Jan 2016
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    ABSTRACT: The GHG-CCI project is one of several projects of the European Space Agency's (ESA) Climate Change Initiative (CCI). The goal of the CCI is to generate and deliver data sets of various satellite-derived Essential Climate Variables (ECVs) in line with GCOS (Global Climate Observing System) requirements. The “ECV Greenhouse Gases” (ECV GHG) is the global distribution of important climate relevant gases – atmospheric CO2 and CH4 – with a quality sufficient to obtain information on regional CO2 and CH4 sources and sinks. Two satellite instruments deliver the main input data for GHG-CCI: SCIAMACHY/ENVISAT and TANSO-FTS/GOSAT. The first order priority goal of GHG-CCI is the further development of retrieval algorithms for near-surface-sensitive column-averaged dry air mole fractions of CO2 and CH4, denoted XCO2 and XCH4, to meet the demanding user requirements. GHG-CCI focuses on four core data products: XCO2 from SCIAMACHY and TANSO and XCH4 from the same two sensors. For each of the four core data products at least two candidate retrieval algorithms have been independently further developed and the corresponding data products have been quality-assessed and inter-compared. This activity is referred to as “Round Robin” (RR) activity within the CCI. The main goal of the RR was to identify for each of the four core products which algorithms should be used to generate the Climate Research Data Package (CRDP). The CRDP will essentially be the first version of the ECV GHG. This manuscript gives an overview of the GHG-CCI RR and related activities. This comprises the establishment of the user requirements, the improvement of the candidate retrieval algorithms and comparisons with ground-based observations and models. The manuscript summarizes the final RR algorithm selection decision and its justification. Comparison with ground-based Total Carbon Column Observing Network (TCCON) data indicates that the “breakthrough” single measurement precision requirement has been met for SCIAMACHY and TANSO XCO2 (< 3 ppm) and TANSO XCH4 (< 17 ppb). The achieved relative accuracy for XCH4 is 3–15 ppb for SCIAMACHY and 2–8 ppb for TANSO depending on algorithm and time period. Meeting the 0.5 ppm systematic error requirement for XCO2 remains a challenge: approximately 1 ppm has been achieved at the validation sites but also larger differences have been found in regions remote from TCCON. More research is needed to identify the causes for the observed differences. In this context GHG-CCI suggests taking advantage of the ensemble of existing data products, for example, via the EnseMble Median Algorithm (EMMA).
    Full-text · Article · Jun 2015 · Remote Sensing of Environment
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    ABSTRACT: A compact automated FTS using direct solar light provide accurate and precise column CO2 and CH4 at the desert playa, where surface albedo is high and the number of validation sites is limited.
    No preview · Article · Feb 2015
  • A. Kuze · T. Imai · H. Suto
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    ABSTRACT: A compact grating imaging spectrometer with sub-nanometer resolution achieved by limiting spectral coverage is presented. Its applications include monitoring gross primary production of forests and farms, cloud top height, and air quality of mega cities.
    No preview · Article · Feb 2015
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    ABSTRACT: Consistent and accurate long-term data sets of global atmospheric concentrations of carbon dioxide (CO2) are required for carbon cycle and climate related research. However, global data sets based on satellite observations may suffer from inconsistencies originating from the use of products derived from different satellites as needed to cover a long enough time period. One reason for inconsistencies can be the use of different retrieval algorithms. We address this potential issue by applying the same algorithm, the Bremen Optimal Estimation DOAS (BESD) algorithm, to different satellite instruments, SCIAMACHY onboard ENVISAT (March 2002–April 2012) and TANSO-FTS onboard GOSAT (launched in January 2009), to retrieve XCO2, the column-averaged dry-air mole fraction of CO2. BESD has been initially developed for SCIAMACHY XCO2 retrievals. Here, we present the first detailed assessment of the new GOSAT BESD XCO2 product. GOSAT BESD XCO2 is a product generated and delivered to the MACC project for assimilation into ECMWF's Integrated Forecasting System (IFS). We describe the modifications of the BESD algorithm needed in order to retrieve XCO2 from GOSAT and present detailed comparisons with ground-based observations of XCO2 from the Total Carbon Column Observing Network (TCCON). We discuss detailed comparison results between all three XCO2 data sets (SCIAMACHY, GOSAT and TCCON). The comparison results demonstrate the good consistency between the SCIAMACHY and the GOSAT XCO2. For example, we found a mean difference for daily averages of −0.60 ± 1.56 ppm (mean difference ± standard deviation) for GOSAT-SCIAMACHY (linear correlation coefficient r = 0.82), −0.34 ± 1.37 ppm (r = 0.86) for GOSAT-TCCON and 0.10 ± 1.79 ppm (r = 0.75) for SCIAMACHY-TCCON. The remaining differences between GOSAT and SCIAMACHY are likely due to non-perfect collocation (±2 h, 10° × 10° around TCCON sites), i.e., the observed air masses are not exactly identical, but likely also due to a still non-perfect BESD retrieval algorithm, which will be continuously improved in the future. Our overarching goal is to generate a satellite-derived XCO2 data set appropriate for climate and carbon cycle research covering the longest possible time period. We therefore also plan to extend the existing SCIAMACHY and GOSAT data set discussed here by using also data from other missions (e.g., OCO-2, GOSAT-2, CarbonSat) in the future.
    No preview · Article · Feb 2015
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    ABSTRACT: This work describes the radiometric calibration of the short-wave infrared (SWIR) bands of two instruments aboard the Greenhouse gases Observing SATellite (GOSAT), the Thermal And Near infrared Sensor for carbon Observations Fourier Transform Spectrometer (TANSO-FTS) and the Cloud and Aerosol Imager (TANSO-CAI). Four vicarious calibration campaigns (VCCs) have been performed annually since June 2009 at Railroad Valley, NV, USA, to estimate changes in the radiometric response of both sensors. While the 2009 campaign $( hbox{VCC}^{2009})$ indicated significant initial degradation in the sensors compared to the prelaunch values, the results presented here show that the stability of the sensors has improved with time. The largest changes were seen in the 0.76 $muhbox{m}$ oxygen A-band for TANSO-FTS and in the 0.380 and 0.674 $muhbox{m}$ bands for TANSO-CAI. This paper describes techniques used to optimize the vicarious calibration of the GOSAT SWIR sensors. We discuss error reductions, relative to previous work, achieved by using higher quality and more comprehensive in situ measurements and proper selection of reference remote sensing products from the Moderate Resolution Imaging Spectroradiometer used in radiative transfer calculations to model top-of-the-atmosphere radiances. In addition, we present new estimates of TANSO-FTS radiometric degradation factors derived by combining the new vicarious calibration results with the time-dependent model provided by Yoshida (2012), which is based on analysis of on-board solar diffuser data. We conclude that this combined model provides a robust correction for TANSO-FTS Level 1B spectra. A detailed error budget for TANSO-FTS vicarious calibration is also provided.
    No preview · Article · Jul 2014 · IEEE Transactions on Geoscience and Remote Sensing
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    ABSTRACT: The Fourier-transform spectrometer on board the Japanese GOSAT (Greenhouse gases Observing SATellite) satellite offers an excellent opportunity to study the impact of instrument resolution on retrieval accuracy of CO_2 and CH_4. This is relevant to further improve retrieval accuracy and to optimize the cost–benefit ratio of future satellite missions for the remote sensing of greenhouse gases. To address this question, we degrade GOSAT measurements with a spectral resolution of ≈ 0.24 cm^(−1) step by step to a resolution of 1.5 cm^(−1). We examine the results by comparing relative differences at various resolutions, by referring the results to reference values from the Total Carbon Column Observing Network (TCCON), and by calculating and inverting synthetic spectra for which the true CO_2 and CH_4 columns are known. The main impacts of degrading the spectral resolution are reproduced for all approaches based on GOSAT measurements; pure forward model errors identified with simulated measurements are much smaller. For GOSAT spectra, the most notable effect on CO_2 retrieval accuracy is the increase of the standard deviation of retrieval errors from 0.7 to 1.0% when the spectral resolution is reduced by a factor of six. The retrieval biases against atmospheric water abundance and air mass become stronger with decreasing resolution. The error scatter increase for CH_4 columns is less pronounced. The selective degradation of single spectral windows demonstrates that the retrieval accuracy of CO_2 and CH_4 is dominated by the spectral range where the absorption lines of the target molecule are located. For both GOSAT and synthetic measurements, retrieval accuracy decreases with lower spectral resolution for a given signal-to-noise ratio, suggesting increasing interference errors.
    No preview · Article · Apr 2014 · Atmospheric Measurement Techniques
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    ABSTRACT: The thermal infrared (TIR) band of Thermal and Near-Infrared Sensor for carbon Observations Fourier Transform Spectrometer (TANSO-FTS) on the Greenhouse gases Observing SATellite (GOSAT) measures a wide range of scene temperatures using a single detector band with broad spectral coverage. This work describes the vicarious radiometric calibration over a large footprint (10.5 km) and high temperature surface using well-calibrated ground-based and airborne FTS sensors. The vicarious calibration campaign of GOSAT was conducted at Railroad Valley, NV in June 2011. During the campaign, the Scanning High-resolution Interferometer Sounder (S-HIS) mounted on the high-altitude NASA ER-2 aircraft observed upwelling radiation and the ground-based Surface-Atmospheric Emitted Radiance Interferometer (S-AERI) observed infrared thermal emission from the atmosphere and the surface at the same location and time as the GOSAT TANSO-FTS. We validated TANSO-FTS TIR radiance with S-HIS radiance using double difference method, which reduces the effect of differences in the observation geometry. In this paper, we estimated the TANSO-FTS Instantaneous Field of View average temperature and emissivity by the coincident S-AERI and S-HIS observed radiance. The double difference between TANSO-FTS and S-HIS result in a difference of 0.5 K at atmospheric window channels (800 ~ 900 cm-1) and CO2 warm brightness temperature channels (700 ~ 750 cm-1), 0.1 K at ozone channels (980 ~ 1080 cm-1), and more than 2 K at CO2 cool brightness temperature channels (650 ~ 700 cm-1). The main reason of remaining errors is attributed to a calibration error in the TANSO-FTS Level 1B product version under evaluation.
    No preview · Article · Jan 2014 · IEEE Transactions on Geoscience and Remote Sensing
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    ABSTRACT: The Fourier-transform spectrometer on board the Japanese GOSAT satellite offers an excellent opportunity to study the impact of instrument resolution on retrieval accuracy of CO2 and CH4. This is relevant to further improve retrieval accuracy and to optimize the cost-benefit ratio of future satellite missions for the remote sensing of greenhouse gases. To address this question, we degrade GOSAT measurements with a spectral resolution of ≈ 0.24 cm-1 step-by-step to a resolution of 1.5 cm-1. We examine the results by comparing relative differences at various resolutions, by referring the results to reference values from the Total Carbon Column Observing Network (TCCON), and by calculating and inverting synthetic spectra for which the true CO2 and CH4 columns are known. The main impacts of degrading the spectral resolution turn out to be consistent for the first two approaches; pure forward model errors identified with simulated measurements are much smaller. For GOSAT spectra, the most notable effect on CO2 retrieval accuracy is the increase of the standard deviation of retrieval errors from 0.7% to 1.0% when the spectral resolution is reduced by a factor of six. The retrieval biases against atmospheric water abundance and airmass become stronger with decreasing resolution. The error scatter increase for CH4 columns is less pronounced. The selective degradation of single spectral windows demonstrates that the retrieval accuracy of CO2 and CH4 is dominated by the spectral range where the absorption lines of the target molecule are located. For both GOSAT and synthetic measurements, retrieval accuracy decreases with lower spectral resolution, suggesting increasing interference errors.
    Full-text · Article · Dec 2013 · Atmospheric Measurement Techniques
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    ABSTRACT: Fourier transform spectrometer (FTS) has many advantages, especially for greenhouse gases and air pollution detection in the atmosphere, because a single instrument can provide wide spectral coverage and high spectral resolution with highly stabilized instrumental line function for all wavenumbers. Several channels are usually required to derive the column amount or vertical profile of a target species. Near infrared (NIR) and shortwave infrared (SWIR) spectral regions are very attractive for remote sensing applications. The GHG and CO of precursors of air pollution have absorption lines in the SWIR region, and the sensitivity against change in the amounts in the boundary layer is high enough to measure mole fractions near the Earth surface. One disadvantage of conventional space-based FTS is the spatial density of effective observation. To improve the effective numbers of observations, an imaging FTS coupled with a two-dimensional (2D)-camera was considered. At first, a mercury cadmium telluride (MCT)-based imaging FTS was considered. However, an MCT-based system requires a calibration source (black body and deep-space view) and a highly accurate and super-low temperature control system for the MCT detector. As a result, size, weight, and power consumption are increased and the cost of the instrument becomes too high. To reduce the size, weight, power consumption, and cost, a commercial 2D indium gallium arsenide (InGaAs) camera can be used to detect SWIR light. To demonstrate a small imaging SWIR-FTS (IS-FTS), an imaging FTS coupled with a commercial 2D InGaAs camera was developed. In the demonstration, the CH4 gas cell was equipped with an IS-FTS for the absorber to make the spectra in the SWIR region. The spectra of CH4 of the IS-FTS demonstration model were then compared with those of traditional FTS. The spectral agreement between the traditional and IS-FTS instruments was very good.
    No preview · Article · Oct 2013 · Proceedings of SPIE - The International Society for Optical Engineering
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    ABSTRACT: Microvibrations onboard greenhouse gases observing satellite (GOSAT) cause scan speed variations in the TANSO Fourier transform spectrometer. The associated periodic sampling errors generate ghost features in O<sub>2</sub> A-band spectra, where surface pressure and aerosol properties are retrieved to determine the optical path through the atmosphere. A correction algorithm has been developed to re-compute the interferograms at equally spaced sampling intervals. The key is to determine iteratively the amplitude and phase of sinusoidal perturbations with predetermined frequencies to minimize the magnitude of the out-of-band ghosts artifacts after correction of the sampling grid. This correction algorithm drastically reduces errors in retrieved surface pressure and improves agreement with ground-based observations.
    No preview · Article · Jul 2013 · Applied Optics
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    ABSTRACT: TANSO-FTS onboard GOSAT has acquired mainly CO2 and CH4 absorption spectra globally since 2009. The GOSAT level 1 algorithms which have been improved since GOSAT launch are described.
    No preview · Conference Paper · Jun 2013
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    ABSTRACT: TANSO-FTS on GOSAT is the first space-borne FTS to cover wide spectra from 0.76 to 15& mu;m measuring both solar-reflection and thermal emission. In addition to atmospheric constituents, it provides aerosol, chlorophyll fluorescence, and surface pressure.
    No preview · Conference Paper · Jun 2013
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    ABSTRACT: Spectroscopic measurements of sunlight backscattered by the Earth's surface is a technique widely used for remote sensing of atmospheric constituent concentrations from space. Thereby, remote sensing of greenhouse gases poses particularly challenging accuracy requirements for instrumentation and retrieval algorithms which, in general, suffer from various error sources. Here, we investigate a method that helps disentangle sources of error for observations of sunlight backscattered from the glint spot on the ocean surface. The method exploits the backscattering characteristics of the ocean surface which is bright for glint geometry but dark for off-glint angles. This property allows for identifying a set of clean scenes where light scattering due to particles in the atmosphere is negligible such that uncertain knowledge of the lightpath can be excluded as a source of error. We apply the method to more than 3 yr of ocean-glint measurements by the Thermal And Near infrared Sensor for carbon Observation (TANSO) - Fourier Transform Spectrometer (FTS) onboard the Greenhouse Gases Observing Satellite (GOSAT) which aims at measuring carbon dioxide (CO2) and methane (CH4) concentrations. The proposed method is able to clearly monitor recent improvements in the instrument calibration of the oxygen (O2) A-band channel and suggests some residual uncertainty in our knowledge about the instrument. We further assess the consistency of CO2 retrievals from several absorption bands between 6400 cm-1 (1565 nm) and 4800 cm-1 (2100 nm) and find that the absorption bands commonly used for monitoring of CO2 dry air mole fractions from GOSAT allow for consistency better than 1.5 ppm. Usage of other bands reveals significant inconsistency among retrieved CO2 concentrations pointing at inconsistency of spectroscopic parameters.
    Full-text · Article · May 2013 · Atmospheric Measurement Techniques
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    ABSTRACT: To monitor the global column concentration of carbon dioxide (CO2) and methane (CH4) from space, the Greenhouse gases Observing SATellite (GOSAT) was launched on January 23, 2009, and has started the operational observation. During four years operational periods, the radiometric, geometric and spectroscopic characterizations of TANSO have been continuously conducted with updating the Level-1 processing algorithm. The latest version of v150 was applied the analog circuit non-linear response correction of band-1 and the correction procedure for improper scan-interval. Newly applied correction methods were supported to derive the accurate XCO2 and XCH4 from Level-2 processing. In parallel, the re-processed products of Level-1 by v150 were conducted for the last 3 years observation data. The evaluated Level-2 data based on v150 suggested us that these products still have following features; the bias offset on M-gain products against H-gain products, the bias difference between land and ocean products, the higher Chi2 for band-2 data caused by scan-interval correction and the biases on brightness temperature at 15-um region against AIRS or IASI products. The main cause of these features is imperfect calibration of TANSO-FTS instruments. In addition, the non-linear mechanism on analog circuit for band1 was identified through the ground-based experiment. The second source of non-linear response excites the artificial signals on absorption lines. Also, the polarization parameters, emissivity of black body and obscuration ratio for TIR will be updated. To improve the spectral quality, we will plan to apply the correction procedure and updated calibration parameters on upcoming Level-1 products. In this presentation, the detail of processing algorithm and parameters derived four years operation will be presented.
    No preview · Article · Apr 2013
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    ABSTRACT: GOSAT which was launched on 23rd of January, 2009 has been operated over four years and an area for improvements such as the observation specifications and hardware methods as well as the measurement accuracy. Therefore we have studied the mission of the GOSAT follow-on, that is GOSAT-2 to leverage greenhouse gases observation from space for the science as well as the practical use such as the effort against global warming by the improvements of the observation performances. At first, we defined the requirements for the concentration measurement accuracies, the estimation error of the net flux and so on which should be accomplished in the next generation based on the GOSAT observation results. Secondly, the specifications of the mission instruments have been studied to satisfy the mission requirements and were defined. To confirm the possibilities of the defined specifications, we have carried out trial manufacture and considerations and redefined the specifications of the mission instruments. The principal improvement point is the increase of the number of the useful data. A large part of GOSAT data have been contaminated with the clouds and only a few percent of the measured data are used. To increase the useful data, we considered the following some kinds of methods. 1. Reduction of the IFOV size; It is possible to reduce the influence of the clouds if the IFOV size becomes small. But it is hard to compensate the reduction of the SNR, so we will give up the reduction of the IFOV size. 2. Adoption of multi FOV;GOSAT has only one FOV and we have considered to increase the number of the FOV to increase the number of the data by the adoption of the multi photo diodes detector. But the optical cross talk which is generated by the multipath reflection between cover glass and photo diodes is too large and exceeded our requirement. So we gave up the adoption of the multi FOVs. 3. Adoption of an intelligent pointing; We are considering to detect the clouds in the FOV of the FTS on orbit and to drive the line of sight to the area where there is no clouds. We are now studying the method to detect the clouds and drive the pointing mirror. 4. Increase of the SNR; In the high-latitude region, the luminance of the solar ray reflection is low, so the SNR is low and it's difficult to observe the high-latitude region of the northern hemisphere in winter. It is possible to extend the observation area to the high-latitude region if the SNR is increased. The increase of the SNR will be realized by the expansion of the aperture size and the adoption of the over sampling. We are now conducting the trial manufacture of the large size corner cube which is used in the Fourier Transform Spectrometer mechanism. In the presentation, I will introduce the mission requirement to GOSAT-2 and the results of the trial manufacture as well as the specifications of the mission instruments which are redefined.
    No preview · Article · Apr 2013
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    ABSTRACT: The Carbon Monitoring Satellite (CarbonSat) is one of two candidate Earth Explorer Opportunity Missions, scheduled for launch in 2018. Its goal is to monitor tropospheric CO2 and CH4 by measuring reflected Sun light in the infrared (four separate observation windows between 0.7 and 2.0 μm). Since the Fourier-transform spectrometer on board the Japanese GOSAT satellite observes at a very similar range as the planned CarbonSat spectrometer, GOSAT spectra offer an excellent opportunity to study the impact of instrument settings on retrieval accuracy. The main topic of this study is the impact of spectral resolution on retrieval accuracy of CO2 and CH4, i.e., does a lowered resolution make spectroscopic errors more obvious? This question is relevant for the CarbonSat mission because the instrument line shape will probably be about five times broader than for GOSAT, but it is also of general interest for the remote sensing of CO2 and CH4. Two different approaches are used to reduce the spectral resolution of the native GOSAT spectra. The columns of CO2 and CH4 that are retrieved from the spectra are then compared to collocated observations from six different observation sites of the Total Carbon Column Observing Network (TCCON). The two instrument settings with a similar spectral resolution but different degradation approach give a similar increase in scatter and decrease of correlation. For the CO2 retrieval accuracy, the only notable effect of lowering the spectral resolution from GOSAT to CarbonSat resolution is the increase of the standard deviation of retrieval errors from 0.7% to 1.0%. Other quality criteria (convergence, inter-stational bias) do not change. For CH4 columns, the standard deviation hardly increases (from 0.9% to 1.0%). Reducing the spectral resolution does not further increase the strength nor the significance of retrieval biases with respect to water abundance, albedo, or solar zenith angle. The selective degradation of single windows demonstrates that the retrieval accuracy of CO2 and CH4 is dominated by the spectral range where the absorption bands of the target molecule are situated.
    No preview · Article · Apr 2013
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    ABSTRACT: Pressing open questions about the carbon cycle can be addressed with precise measurements of the three most abundant CO2 isotopologues 16O12C16O, 16O13C16O, and O16C12O18. Such measurements can, e.g., help to further constrain oceanic and biospheric net fluxes or to differentiate between the gross biospheric fluxes photosynthesis and respiration. The 2041-2047nm (about 4885-4900cm-1) spectral region contains separated absorption lines of the three most abundant CO2 isotopologues. Their spectral properties make this spectral region well suited for the use of a light path proxy method for the retrieval of δC13 and δO18 (the ratio of heavier to lighter isotopologues relative to a standard). An optimal estimation based light path proxy retrieval for δC13 and δO18 has been set up, applicable to GOSAT (Greenhouse gases Observing Satellite) and ground-based FTS (Fourier transform spectrometer) measurements. Initial results show that it is possible to retrieve δC13 and δO18 from ground-based FTS instruments with a precision of 0.6-1.6‰ and from GOSAT with a precision of about 30‰. Comparison of the achievable precision with the expected atmospheric signals shows that ground-based FTS remote sensing measurements have the potential to gain valuable information on δC13 and δO18 if averaging a sufficient number of measurements. It seems unlikely that this applies also to GOSAT because of the lower precision and a conceptual larger sensitivity to scattering related errors in satellite viewing geometry.
    No preview · Article · Nov 2012 · Journal of Quantitative Spectroscopy and Radiative Transfer
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    ABSTRACT: To observe the global column concentration of carbon dioxide (CO2) and methane (CH4) from space, the Greenhouse gases Observing SATellite (GOSAT) was launched on January 23, 2009, and has started the operational observation. Thermal and Near Infrared Sensor for Carbon Observation- Fourier Transform Spectrometer (TANSO-FTS) has been continuously measuring CO2 and CH4 distributions globally, and the retrieved column CO2 and CH4 data have been distributed to the public. Over three-years operational periods, the useful scientific data sets and interesting articles for carbon source/sink evaluation were produced and published, and these results have been supporting to well understanding of carbon cycle. Currently, the importance of space-based carbon observation has been approved and desired the continuous observation in toward. Through the TANSO-FTS operation with the radiometric, geometric and spectroscopic characterizations, we learned how to improve the accuracy of XCO2 and XCH4 based on short-wavelength FTS. The correction procedures for micro-vibration from companion components, non-linear response of analogue and digitizing circuit are key role on the current on-board operating TANSO-FTS. On instrumental aspects, the robustness and improvements will be required on the future mission. To elucidate the carbon cycle more precisely, our experiences have to be summarized and applied in the future missions. In this presentation, the detail of lessons and learned from TANSO-FTS operation will be presented.
    No preview · Article · Oct 2012 · Proceedings of SPIE - The International Society for Optical Engineering
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    ABSTRACT: The Thermal And Near infrared Sensor for carbon Observation Fourier-Transform Spectrometer (TANSO-FTS) onboard the Greenhouse gases Observing SATellite (GOSAT) (nicknamed "Ibuki") has been providing global space-borne observations of carbon dioxide (CO2) and methane (CH4) since 2009. In this paper, we first describe the version V150.151 operational Level 1 algorithms that produce radiance spectra from the acquired interferograms. Second, we will describe the on-orbit characteristics and calibration of TANSO-FTS. Overall function and performance such as signal to noise ratio and spectral resolution are within design objectives. Correction methods of small on-orbit degradations and anomalies, which have been found since launch, are described. Lastly, calibration of TANSO Cloud and Aerosol Imager (TANSO-CAI) are summarized.
    No preview · Article · Oct 2012 · Atmospheric Measurement Techniques