Prof. Ryoichi Imasu Profile

Prof. Ryoichi Imasu

Professor/Sr. Researcher at Univ. of Tokyo

SPIE Involvement:

Conference Program Committee | Author

Publications (34)

Proceedings Article | 16 December 2021 Paper

Relationship between the concentration of fine particulate matter and aerosol optical depth in the Middle Urals

A. Luzhetskaya, E. Nagovitsyna, E. Omelkova, V. Poddubny, A. Shchelkanov, V. Gadelshin, Y. Matsumi, R. Imasu

Proceedings Volume 11916, 119164A (2021) https://doi.org/10.1117/12.2603473

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Proceedings Article | 12 November 2020 Paper

Atmospheric methane retrieval from TANSO-FTS/GOSAT-2 thermal IR spectra using FIRE-ARMS software

Ilya Zadvornykh, Konstantin Gribanov, Vyacheslav Zakharov, Ryoichi Imasu

Proceedings Volume 11560, 115604Y (2020) https://doi.org/10.1117/12.2575622

KEYWORDS: Methane, Satellites, Short wave infrared radiation, Thermography, Atmospheric monitoring, Infrared radiation, Gases, Atmospheric modeling, Earth's atmosphere, Sensors

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Proceedings Article | 18 December 2019 Paper

The feasibility of 13CO2 retrieval from IASI/METOP spectra

Ilya Zadvornykh, Konstantin Gribanov, Vyacheslav Zakharov, Ryoichi Imasu

Proceedings Volume 11208, 112085F (2019) https://doi.org/10.1117/12.2540923

KEYWORDS: Earth's atmosphere, Atmospheric modeling, Carbon, Carbon dioxide, Molecules, Climatology, Atmospheric physics

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Proceedings Article | 13 December 2018 Paper

Retrieving the 13CO2/12CO2 isotopic ratio from high resolution ground-based FTIR measurement in Tsukuba

N. Rokotyan, R. Imasu, I. Morino, K. Gribanov, V. Zakharov

Proceedings Volume 10833, 108330N (2018) https://doi.org/10.1117/12.2504590

KEYWORDS: Carbon monoxide, FT-IR spectroscopy, Remote sensing, Atmospheric sensing, Spectroscopy, Carbon, Transmittance, Earth's atmosphere, Atmospheric monitoring, Atmospheric modeling

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Proceedings Article | 13 December 2018 Paper

Methane vertical profiles retrieval from IASI/METOP and TANSO-FTS/GOSAT data

Ilya Zadvornykh, Konstantin Gribanov, Vyacheslav Zakharov, Ryoichi Imasu

Proceedings Volume 10833, 108336A (2018) https://doi.org/10.1117/12.2504648

KEYWORDS: Short wave infrared radiation, Methane, Infrared radiation, Satellites, Thermography, Spectrometers, Sensors, Fourier transforms, Inverse problems, Remote sensing

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SPIE Journal Paper | 31 October 2018

Development of the empirical orthogonal functions-based algorithm for the retrievals of atmospheric CO₂ total column amount from space-borne observations of reflected sunlight

Andrey Bril, Shamil Maksyutov, Sergey Oshchepkov, Yukio Yoshida, Ryoichi Imasu, Chisa Iwasaki, Anatoli Chaikovsky, Anton Fedarenka

JARS, Vol. 12, Issue 04, 046012, (October 2018) https://doi.org/10.1117/12.10.1117/1.JRS.12.046012

KEYWORDS: Algorithm development, Satellites, Carbon monoxide, Data processing, Atmospheric optics, Earth observing sensors, Detection and tracking algorithms, Clouds, Aerosols, Carbon dioxide

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Proceedings Article | 30 November 2017 Paper

The joint methane profiles retrieval approach from GOSAT TIR and SWIR spectra

Ilya Zadvornykh, Konstantin Gribanov, Vyacheslav Zakharov, Ryoichi Imasu

Proceedings Volume 10466, 104664G (2017) https://doi.org/10.1117/12.2288700

KEYWORDS: Methane, Short wave infrared radiation, Atmospheric modeling, Satellites, Spectroscopy, Gases, Infrared radiation, Solar radiation models, Thermography, Infrared spectroscopy

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Proceedings Article | 30 November 2017 Paper

Regarding retrievals of methane in the atmosphere from IASI/Metop spectra and their comparison with ground-based FTIR measurements data

M. Yu. Khamatnurova, K. Gribanov, V. Zakharov, N. Rokotyan, R. Imasu

Proceedings Volume 10466, 104666Y (2017) https://doi.org/10.1117/12.2288687

KEYWORDS: Atmospheric sensing, FT-IR spectroscopy, Methane, Satellites, Remote sensing, Inverse problems, Spectroscopy

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Proceedings Article | 30 November 2017 Paper

Bottlenecks in the remote sensing of the 13CO2/12CO2 isotopic ratio from GOSAT measurements

N. Rokotyan, R. Imasu, K. Gribanov, V. Zakharov

Proceedings Volume 10466, 104661Q (2017) https://doi.org/10.1117/12.2287960

KEYWORDS: Remote sensing, Carbon dioxide, Climate change

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SPIE Journal Paper | 12 September 2017

Ground-based measurement of column-averaged mixing ratios of methane and carbon dioxide in the Sichuan Basin of China by a desktop optical spectrum analyzer

Xiu-Chun Qin, Tomoki Nakayama, Yutaka Matsumi, Masahiro Kawasaki, Akiko Ono, Sachiko Hayashida, Ryoichi Imasu, Li-Ping Lei, Isao Murata, Takahiro Kuroki, Masafumi Ohashi

JARS, Vol. 12, Issue 01, 012002, (September 2017) https://doi.org/10.1117/12.10.1117/1.JRS.12.012002

KEYWORDS: Methane, Carbon monoxide, Satellites, Spectrum analysis, Absorption, Calibration, Atmospheric optics, Global Positioning System, Climate change, Near infrared

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Proceedings Article | 29 November 2016 Paper

The development of algorithms for atmospheric methane distribution retrieval from IASI/METOP spectra and their validation with MACC/ECMWF reanalysis data

M. Yu. Khamtnurova, K. Gribanov, V. Zakharov, R. Imasu

Proceedings Volume 10035, 1003577 (2016) https://doi.org/10.1117/12.2249468

KEYWORDS: Algorithm development, Atmospheric sensing, Methane, Satellites, Scattering, Atmospheric modeling, Humidity, Atmospheric monitoring, Atmospheric optics, Matrices

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Proceedings Article | 29 November 2016 Paper

GOSAT TIR and SWIR spectra analysis for CO2 and CH4 profiles retrieval

Ilya Zadvornykh, Konstantin Gribanov, Ryoichi Imasu

Proceedings Volume 10035, 100350P (2016) https://doi.org/10.1117/12.2249494

KEYWORDS: Short wave infrared radiation, Radiative transfer, Methane, Atmospheric modeling, Gases, Satellites, Spectroscopy, Atmospheric physics, Thermal modeling, Thermography

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Proceedings Article | 28 November 2012 Paper

Characterization and validation of CO2 and CH4 products derived from the GOSAT thermal infrared band

Tomoaki Tanaka, Kei Shiomi, Shuji Kawakami, Naoko Saitoh, Ryoichi Imasu, Makoto Inoue, Isamu Morino, Osamu Uchino, Colm Sweeney, Pieter Tans

Proceedings Volume 8528, 852810 (2012) https://doi.org/10.1117/12.979663

KEYWORDS: Carbon dioxide, Gases, Infrared radiation, Thermography, Atmospheric monitoring, Infrared sensors, Analytical research, Atmospheric sensing, Satellites, Methane

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Proceedings Article | 13 November 2010 Paper

Retrieval of minor constituents from thermal infrared spectra observed by GOSAT TANSO-FTS sensor

Ryoichi Imasu, Yoji Hayashi, Akiko Inagoya, Naoko Saitoh, Kei Shiomi

Proceedings Volume 7857, 785708 (2010) https://doi.org/10.1117/12.870684

KEYWORDS: Carbon dioxide, Sensors, Calibration, Infrared radiation, Thermography, Ozone, Infrared sensors, Satellites, Temperature metrology, Black bodies

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Proceedings Article | 23 September 2009 Paper

Upper-atmospheric CO2 concentration retrieved from thermal infrared spectra observed using GOSAT TANSO-FTS (TIR) sensor

Ryoichi Imasu, Naoko Saitoh, Kei Shiomi, Hiroshi Suto, Akihiko Kuze, Masakatsu Nakajima

Proceedings Volume 7474, 74740K (2009) https://doi.org/10.1117/12.830387

KEYWORDS: Sensors, Carbon dioxide, Calibration, Black bodies, Infrared radiation, Thermography, Spectroscopy, Infrared sensors, Interferometry, Phase interferometry

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Proceedings Article | 11 December 2008 Paper

Radiometric calibration accuracy of GOSAT-TANSO-FTS (TIR) relating to CO2 retrieval error

Ryoichi Imasu, Naoko Saitoh, Yosuke Niwa, Hiroshi Suto, Akihiko Kuze, Kei Shiomi, Masakatsu Nakajima

Proceedings Volume 7149, 71490B (2008) https://doi.org/10.1117/12.806145

KEYWORDS: Interferometry, Calibration, Sensors, Phase interferometry, Black bodies, Carbon dioxide, Thermography, Fourier transforms, Mirrors, Signal detection

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Proceedings Article | 17 October 2007 Paper

Retrieval performance of GOSAT thermal infrared FTS sensor for measuring CO2 concentrations

Ryoichi Imasu, Naoko Saitoh, Yosuke Niwa

Proceedings Volume 6744, 67440F (2007) https://doi.org/10.1117/12.737796

KEYWORDS: Carbon monoxide, Sensors, Infrared radiation, Thermography, Infrared sensors, Atmospheric modeling, Data modeling, Carbon dioxide, Satellites, Short wave infrared radiation

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Proceedings Article | 22 December 2006 Paper

Assessment of uncertainty in CO2 concentrations retrieved from thermal infrared spectra of GOSAT satellite

N. Saitoh, Y. Ota, S. Taguchi, R. Imasu

Proceedings Volume 6405, 640508 (2006) https://doi.org/10.1117/12.693803

KEYWORDS: Carbon monoxide, Satellites, Computer simulations, Infrared radiation, Temperature metrology, Gases, Carbon dioxide, Sensors, Troposphere, Thermography

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Proceedings Article | 13 December 2006 Paper

CO2 retrieval performance of TANSO-FTS (TIR) sensor aboard greenhouse gases observing satellite (GOSAT)

Ryoichi Imasu, Naoko Saitoh, Yoshifumi Ota, Shoichi Taguchi

Proceedings Volume 6580, 65800Z (2006) https://doi.org/10.1117/12.724963

KEYWORDS: Carbon dioxide, Sensors, Satellites, Infrared radiation, Thermography, Data modeling, Infrared sensors, Error analysis, Carbon monoxide, Gases

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Proceedings Article | 12 December 2006 Paper

Method and results of retrieval of HDO/H2O in atmosphere from IMG/ADEOS and FTIR data

A. Yu. Toptygin, K. Gribanov, V. Zakharov, Y. Kasai, A. Kagawa, Y. Murayama, R. Imasu, G. Schmidt, G. Hoffmann, J. Jouzel

Proceedings Volume 6580, 65800X (2006) https://doi.org/10.1117/12.724949

KEYWORDS: FT-IR spectroscopy, Atmospheric modeling, Transmittance, Solar radiation models, Error analysis, Spectral resolution, Spectroscopy, Atmospheric monitoring, Atmospheric sensing, Knowledge management

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Here we present a Principal Components (PCs) method of retrieval of the HDO/H₂O vertical profile using atmospheric radiances observed from space by sensor like IMG as well as atmospheric transmittance spectra observed by ground based FTIR. The method is based on the expansion of the retrieved profile on eigenvectors of covariance matrix of model profiles extracted from the isotopic Atmospheric General Circulation Model (AGCM). A priori information of covariance matrix compensates partially the lack of information containing in weighting functions for HDO in lower atmospheric layer (0-1 km) and layers above 10 km. Error estimation of the retrieval scheme was made using closed model computations with synthetic spectra ofIMG and known sets of T, H₂0, HDO profiles and its value is within 8% - 70% for vertical profile and not greater than l8% for columnar value of HDO/H20 ratio. The method was applied to IMG/ADEOS spectra measured over the ocean in clear sky conditions. Latitudinal distributions ofHDO/H20 profile and columnar HDO/H₂0 ratio are retrieved over Pacific Ocean for the time interval from winter of 1996 to summer of 1997. The retrieved HDO/H₂0 from IMG/ADEOS data and simulated with isotopic AGCM are in a good agreement. FTIR is Poker Flat high resolution ground based Fourier transform spectrometer for up-looking observation of atmosphere in the spectral range from 750-4300 cm^-1 with resolution 0.0019 cm^-1 and high signal to noise ratio. The spectrometer is located at the Poker Flat Research Range (Altitude 0.61km; latitude 65.11N; longitude 147.42W) of the Geophysical Institute at the University of Alaska Fairbanks. Poker Flat FTS is operating from 1999, observation modes are atmospheric emission and solar radiation absorption. The measured atmospheric traiismittances are supported by sonde observations of T and water vapour profiles. The HDO/H₂0 PCs retrieval method was also adapted for using the high spectral resolution atmospheric transmittances observed by FTIR. Linear regression of PCs of the HDO/H₂0 profiles was obtained in this case. Error estimation of the retrieval scheme was made using closed model computations with synthetic spectra ofthe FTIR and known sets of T, H₂0, HDO profiles and its value is within 6% - 67% for vertical profile but not greater than lO% for columnar value of HDO/H₂0 ratio. As an example, HDO/H₂0 vertical profiles were retrieved using a few samples of FTIR spectra observed at the Poker Flat Research Range from 2000 to 2004 and compared with isotope AGCM outputs for Alaska's atmosphere.