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Your search keyword '"KASABA, Yasumasa"' showing total 17 results
Start Over Author "KASABA, Yasumasa" Publisher american geophysical union
17 results on '"KASABA, Yasumasa"'

1. Variations in Vertical CO/CO2 Profiles in the Martian Mesosphere and Lower Thermosphere Measured by the ExoMars TGO/NOMAD: Implications of Variations in Eddy Diffusion Coefficient

Author

Yoshida, Nao, Nakagawa, Hiromu, Aoki, Shohei, Erwin, Justin, Vandaele, Ann Carine, Daerden, Frank, Thomas, Ian, Trompet, Loïc, Koyama, Shungo, Terada, Naoki, Neary, Lori, Murata, Isao, Villanueva, Geronimo, Liuzzi, Giuliano, Lopez‐Valverde, Miguel Angel, Brines, Adrian, Modak, Ashimananda, Kasaba, Yasumasa, Ristic, Bojan, Bellucci, Giancarlo, López‐Moreno, José Juan, Patel, Manish, Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, UK Space Agency, and Agenzia Spaziale Italiana

Subjects
Geophysics, Retrieval, Atmospheric composition, General Earth and Planetary Sciences, Mars, Eddy diffusion coefficient, Spectroscopy, Mesosphere
Abstract

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited., Using the Nadir and Occultation for MArs Discovery instrument aboard Trace Gas Orbiter, we derived the CO/CO2 profiles between 75 and 105 km altitude with the equivalent width technique. The derived CO/CO2 profiles showed significant seasonal variations in the southern hemisphere with decreases near perihelion and increases near aphelion. The estimation of the CO/CO2 profiles with a one-dimensional photochemical model shows that an altitude-dependent eddy diffusion coefficient better reproduces the observed profiles than a vertically uniform one. Our estimation suggests that the eddy diffusion coefficient in Ls = 240–270 is uniformly larger by a factor of ∼2 than that in Ls = 90–120 in the southern hemisphere, while they are comparable in the northern hemisphere. This fact demonstrates that the eddy diffusion coefficient is variable with season and latitude. © 2022. The Authors., The NOMAD experiment is led by the Royal Belgian Institute for Space Aeronomy (IASB-BIRA), assisted by Co-PI teams from Spain (IAA-CSIC), Italy (INAF-IAPS), and the United Kingdom (Open University). This project acknowledges funding by the Belgian Science Policy Office (BELSPO), with the financial and contractual coordination by the ESA Prodex Office (PEA 4000103401, 4000121493), by Spanish Ministry of Science and Innovation (MCIU) and by European funds under Grants PGC2018-101836-B-I00 and ESP2017-87143-R (MINECO/FEDER), as well as by UK Space Agency through Grants ST/V002295/1, ST/V005332/1, and ST/S00145x/1 and Italian Space Agency through Grant 2018-2-HH.0. This work was supported by the Belgian Fonds de la Recherche Scientifique–FNRS under Grant No. 30442502 (ET_HOME). The IAA/CSIC team acknowledges financial support from the State Agency for Research of the Spanish MCIU through the “Center of Excellence Severo Ochoa” award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709). US investigators were supported by the National Aeronautics and Space Administration. Canadian investigators were supported by the Canadian Space Agency. Y. N. is supported by The international Joint Graduate Program in Earth and Environmental Sciences, Tohoku University (GP-EES), and the Japanese Society for the Promotion of Science (JP21J13710). This work was supported by JSPS KAKENHI Grant Nos. 20H04605 and 19K03943.

Published
2022

2. Variations in Vertical CO/CO2 Profiles in the Martian Mesosphere and Lower Thermosphere Measured by the ExoMars TGO/NOMAD: Implications of Variations in Eddy Diffusion Coefficient

Author

Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, UK Space Agency, Agenzia Spaziale Italiana, Yoshida, Nao, Nakagawa, Hiromu, Aoki, Shohei, Erwin, Justin T., Vandaele, Ann Carine, Daerden, Frank, Thomas, Ian R., Trompet, Loïc., Koyama, Shungo, Terada, Naoki, Neary, Lori, Murata, Isao, Villanueva, Geronimo L., Liuzzi, Giuliano, López-Valverde, M. A., Brines, Adrian, Modak, Ashimananda, Kasaba, Yasumasa, Ristic, Bojan, Bellucci, Giancarlo, López-Moreno, José Juan, Patel, Manish R., Ministerio de Ciencia e Innovación (España), European Commission, Belgian Science Policy Office, UK Space Agency, Agenzia Spaziale Italiana, Yoshida, Nao, Nakagawa, Hiromu, Aoki, Shohei, Erwin, Justin T., Vandaele, Ann Carine, Daerden, Frank, Thomas, Ian R., Trompet, Loïc., Koyama, Shungo, Terada, Naoki, Neary, Lori, Murata, Isao, Villanueva, Geronimo L., Liuzzi, Giuliano, López-Valverde, M. A., Brines, Adrian, Modak, Ashimananda, Kasaba, Yasumasa, Ristic, Bojan, Bellucci, Giancarlo, López-Moreno, José Juan, and Patel, Manish R.

Abstract

Using the Nadir and Occultation for MArs Discovery instrument aboard Trace Gas Orbiter, we derived the CO/CO2 profiles between 75 and 105 km altitude with the equivalent width technique. The derived CO/CO2 profiles showed significant seasonal variations in the southern hemisphere with decreases near perihelion and increases near aphelion. The estimation of the CO/CO2 profiles with a one-dimensional photochemical model shows that an altitude-dependent eddy diffusion coefficient better reproduces the observed profiles than a vertically uniform one. Our estimation suggests that the eddy diffusion coefficient in Ls = 240–270 is uniformly larger by a factor of ∼2 than that in Ls = 90–120 in the southern hemisphere, while they are comparable in the northern hemisphere. This fact demonstrates that the eddy diffusion coefficient is variable with season and latitude. © 2022. The Authors.

Published
2022

3. Azimuthal Variation in the Io Plasma Torus Observed by the Hisaki Satellite From 2013 to 2016

Author

Steffl, A., Bagenal, F., Delamere, P., Yoneda, M., Tsuchiya, Fuminori, Arakawa, Ryo, Misawa, Hiroaki, Kagitani, Masato, Koga, Ryoichi, Suzuki, Fumiharu, Hikida, Reina, Yoshioka, Kazuo, Kimura, Tomoki, Kasaba, Yasumasa, Murakami, Go, Yoshikawa, Ichiro, and Yamazaki, Atsushi

Subjects
Physics, Azimuth, Geophysics, Space and Planetary Science, Satellite, Torus, Astrophysics, Plasma, Variation (astronomy)
Abstract

著者人数: 17名, Accepted: 2019-04-15, 資料番号: SA1190016000

Published
2019

4. Energetic Electron Precipitation Associated With Pulsating Aurora Observed by VLF Radio Propagation During the Recovery Phase of a Substorm on 27 March 2017

Author

Connors, Martin, Shoji, M., Tsuchiya, Fuminori, Hirai, Asuka, Obara, Takahiro, Misawa, Hiroaki, Kurita, Satoshi, Miyoshi, Yoshizumi, Shiokawa, Kazuo, Ozaki, Mitsunori, Kasahara, Yoshiya, Kumamoto, Atsushi, Kasaba, Yasumasa, Matsuoka, Ayako, and Shinohara, Iku

Subjects
Physics, 010504 meteorology & atmospheric sciences, Electron precipitation, Geophysics, 010502 geochemistry & geophysics, 01 natural sciences, Radio propagation, symbols.namesake, Van Allen radiation belt, Substorm, symbols, General Earth and Planetary Sciences, 0105 earth and related environmental sciences, Recovery phase
Abstract

著者人数: 15名, Accepted: 2018-10-22, 資料番号: SA1180264000

Published
2018

8. Weakening of Jupiter's Main Auroral Emission during January 2014

Author

Badman, Sarah V., Bonfond, B., Gray, R. L., Melin, H., Nichols, J. D., Steffl, A. J., Fujimoto, Masaki, Kasaba, Yasumasa, Kasahara, Satoshi, Kimura, Tomoki, Tao, Chihiro, Tsuchiya, Fuminori, Yamazaki, Atsushi, Yoneda, Mizuki, Yoshikawa, Ichiro, and Yoshioka, Kazuo

Abstract

著者人数: 16名, Accepted: 2016-01-22, 資料番号: SA1150287000

Published
2016

11. Universal time control of AKR: Earth is a spin-modulated variable radio source

Author

Morioka, Akira, Miyoshi, Yoshizumi, Kurita, Satoshi, Kasaba, Yasumasa, Angelopoulos, Vassilis, Misawa, Hiroaki, Kojima, Hirotsugu, and McFadden, James P.

Subjects
Astrophysics::High Energy Astrophysical Phenomena, Physics::Space Physics, Astrophysics::Earth and Planetary Astrophysics, UT control, spin modulation, Variable radio source, AKR frequency variation
Abstract

Auroral kilometric radiation (AKR) is known to be transient emissions generated by rapidly accelerated electrons together with sudden auroral activation in the polar magnetosphere. In contrast, the characteristics and relationship with the auroral acceleration of rather continuous AKR emissions are not well understood. We examine the emission using long-term data and report that the continuous AKR emission frequency changes with universal time (UT) as the Earth rotates, indicating that the Earth is a spin-modulated variable radio source. The observed UT variation of AKR frequency means that the acceleration altitude changes periodically with planetary rotation. The observations indicate that the diurnal wobble of the tilted geomagnetic field in the solar wind flow alters the magnetosphere-ionosphere (M-I) coupling state in the polar magnetosphere, giving rise to periodic variation of auroral particle acceleration altitude. These observations of planetary radio wave properties provide insight into the physics of planetary particle acceleration.

Published
2013

12. Statistical Studies of Plasma Waves and Backstreaming Electrons in the Terrestrial Electron Foreshock Observed by GEOTAIL

Author

笠羽, 康正, 松本, 紘, 大村, 善治, Anderson, R. R., 向井, 利典, 齋藤, 義文, 山本, 達人, 國分, 征, Kasaba, Yasumasa, Matsumoto, Hiroshi, Omura, Yoshiharu, Mukai, Toshifumi, Saito, Yoshifumi, Yamamoto, Tatsundo, Kokubun, Susumu, 笠羽, 康正, 松本, 紘, 大村, 善治, Anderson, R. R., 向井, 利典, 齋藤, 義文, 山本, 達人, 國分, 征, Kasaba, Yasumasa, Matsumoto, Hiroshi, Omura, Yoshiharu, Mukai, Toshifumi, Saito, Yoshifumi, Yamamoto, Tatsundo, and Kokubun, Susumu

Abstract

Accepted: 1999-09-01

Published
2015

13. Storm-Time Convection Electric Field in the Near-Earth Plasma Sheet

Author

堀, 智昭, Lui, A. T. Y., 大谷, 晋一, C:son Brandt, P., Mauk, B. H., McEntire, R. W., 前澤, 冽, 向井, 利典, 笠羽, 康正, 早川, 基, Hori, Tomoaki, Ohtani, Shinichi, Maezawa, Kiyoshi, Mukai, Toshifumi, Kasaba, Yasumasa, Hayakawa, Hajime, 堀, 智昭, Lui, A. T. Y., 大谷, 晋一, C:son Brandt, P., Mauk, B. H., McEntire, R. W., 前澤, 冽, 向井, 利典, 笠羽, 康正, 早川, 基, Hori, Tomoaki, Ohtani, Shinichi, Maezawa, Kiyoshi, Mukai, Toshifumi, Kasaba, Yasumasa, and Hayakawa, Hajime

Abstract

Accepted: 2005-02-04

Published
2015

17. Universal time control of AKR: Earth is a spin-modulated variable radio source

Author

90785495, 10215254, Morioka, Akira, Miyoshi, Yoshizumi, Kurita, Satoshi, Kasaba, Yasumasa, Angelopoulos, Vassilis, Misawa, Hiroaki, Kojima, Hirotsugu, McFadden, James P., 90785495, 10215254, Morioka, Akira, Miyoshi, Yoshizumi, Kurita, Satoshi, Kasaba, Yasumasa, Angelopoulos, Vassilis, Misawa, Hiroaki, Kojima, Hirotsugu, and McFadden, James P.

Abstract

Auroral kilometric radiation (AKR) is known to be transient emissions generated by rapidly accelerated electrons together with sudden auroral activation in the polar magnetosphere. In contrast, the characteristics and relationship with the auroral acceleration of rather continuous AKR emissions are not well understood. We examine the emission using long-term data and report that the continuous AKR emission frequency changes with universal time (UT) as the Earth rotates, indicating that the Earth is a spin-modulated variable radio source. The observed UT variation of AKR frequency means that the acceleration altitude changes periodically with planetary rotation. The observations indicate that the diurnal wobble of the tilted geomagnetic field in the solar wind flow alters the magnetosphere-ionosphere (M-I) coupling state in the polar magnetosphere, giving rise to periodic variation of auroral particle acceleration altitude. These observations of planetary radio wave properties provide insight into the physics of planetary particle acceleration.

Published
2013

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