Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Be for the detectability of solar proton eventsSchaar, K.*; Spiegl, T.*; Langematz, U.*; Sato, Tatsuhiko; Mekhaldi, F.*; Kunze, M.*; Miyake, Fusa*; Yoden, Shigeo*
Journal of Geophysical Research; Atmospheres, 129(11), p.e2023JD040463_1 - e2023JD040463_28, 2024/06
Times Cited Count：1 Percentile：41.97(Meteorology & Atmospheric Sciences)Usui, Yoshiya*; Ueshima, Makoto*; Hase, Hideaki*; Ichihara, Hiroshi*; Aizawa, Koki*; Koyama, Takao*; Sakanaka, Shinya*; Ogawa, Tsutomu*; Yamaya, Yusuke*; Nishitani, Tadashi*; et al.
Journal of Geophysical Research; Solid Earth, 129(5), p.e2023JB028522_1 - e2023JB028522_22, 2024/05
Times Cited Count：2 Percentile：69.68(Geochemistry & Geophysics)We elucidated the crustal heterogeneities beneath a strain concentration area on the back-arc side of the northeastern Japan Arc based on electrical resistivity. By deploying magnetotelluric surveys, we revealed the three-dimensional electrical resistivity structure in the crust, suggesting the coexistence of two types of strain-concentration mechanisms in the strain-concentration area. The shallow conductive layers and lower-crustal conductors appear to act as low-elastic-modulus and low-viscosity areas, respectively, and are responsible for the strain concentration. We found a spatial correlation between the edges of the lower-crustal conductors and the epicenters of large intraplate earthquakes. Weak shear zones in the conductive lower crust may cause stress loading on faults in the brittle upper crust, resulting in large earthquakes. We also identified vertical conductors ranging from the lower crust to Quaternary volcanoes, which may indicate fluid paths to these volcanoes.
Wada, Yuki*; Kamogawa, Masashi*; Kubo, Mamoru*; Enoto, Teruaki*; Hayashi, Shugo*; Sawano, Tatsuya*; Yonetoku, Daisuke*; Tsuchiya, Harufumi
Journal of Geophysical Research; Atmospheres, 128(21), p.e2023JD039354_1 - e2023JD039354_20, 2023/11
Times Cited Count：1 Percentile：13.75(Meteorology & Atmospheric Sciences)Abeykoon, S.*; Howard, C.*; Dominijanni, S.*; Eberhard, L.*; Kurnosov, A.*; Frost, D. J.*; Boffa Ballaran, T.*; Terasaki, Hidenori*; Sakamaki, Tatsuya*; Suzuki, Akio*; et al.
Journal of Geophysical Research; Solid Earth, 128(9), p.e2023JB026710_1 - e2023JB026710_17, 2023/09
Times Cited Count：2 Percentile：32.37(Geochemistry & Geophysics)Small amounts of iron sulphide minerals are found in most rocks from the Earth's mantle and as inclusions trapped in natural diamonds. Hydrogen may dissolve into iron sulphide minerals under high pressures and temperature, but is most likely lost once pressure and temperature are removed. In this study, we determined deuterium contents in iron sulphide, held under high pressure and temperature conditions, using neutron diffraction measurements with 6-ram multi-anvil press at PLANET, J-PARC. Deuterium contents in iron sulphide were measured at high-P, up to 11.4 GPa and high-T to 1300 K in in situ neutron diffraction experiments. The total deuterium content increases with both P and T. The results are used to estimate hydrogen contents of iron sulphide minerals in the deep continental lithospheric mantle, which are found to be in the range 1700-2700 ppm. This corresponds to approximately 2-3 ppm of hydrogen in the bulk mantle.
Wada, Yuki*; Wu, T.*; Wang, D.*; Enoto, Teruaki*; Nakazawa, Kazuhiro*; Morimoto, Takeshi*; Nakamura, Yoshitaka*; Shinoda, Taro*; Tsuchiya, Harufumi
Journal of Geophysical Research; Atmospheres, 128(15), p.e2023JD038606_1 - e2023JD038606_9, 2023/08
Times Cited Count：3 Percentile：40.74(Meteorology & Atmospheric Sciences)Be produced by the strongest solar proton event during the holoceneSpiegl, T. C.*; Yoden, Shigeo*; Langematz, U.*; Sato, Tatsuhiko; Chhin, R.*; Noda, Satoshi*; Miyake, Fusa*; Kusano, Kanya*; Schaar, K.*; Kunze, M.*
Journal of Geophysical Research; Atmospheres, 127(13), p.e2021JD035658_1 - e2021JD035658_21, 2022/07
Times Cited Count：6 Percentile：45.37(Meteorology & Atmospheric Sciences)The abundance of cosmogenic isotopes in natural archives carries important information about the complex pathways from their source in the upper atmosphere to their deposition via atmospheric transport processes. Here, we use a new modelling framework to (a) estimate the Be production yield for the 774 CE/775 event, (b) evaluate the performance of our model framework by comparing the model results to four ice core records and (c) investigate the atmospheric pathways with a state-of-the-art climate model in detail. The results give new constraints regarding the seasonal timing of the event, underpin the role of the background conditions in the stratosphere, and highlight regional variations in the cosmogenic surface flux.
Nakajima, Toru; Kawakami, Tetsuo*; Iwano, Hideki*; Danhara, Toru*; Sakai, Harutaka*
Journal of Geophysical Research; Solid Earth, 127(5), p.e2021JB023630_1 - e2021JB023630_33, 2022/05
Times Cited Count：3 Percentile：30.02(Geochemistry & Geophysics)The thermochronological methods were applied to the Higher Himalayan Crystalline (HHC) nappe and the underlying Lesser Himalayan sediments (LHS) to elucidate the denudation process of the middle- and upper-crust of eastern Nepal over the geological time scale. The thermochronological inverse analysis was undertaken for new results of fission-track (FT) age and FT length data of zircon and apatite in order to reconstruct the time-temperature (
) paths in the temperature range of 60-350 degree. Eight paths obtained along the across-strike section showed that the cooling process of the HHC nappe was characterized by following three aspects: (1) gradual cooling followed by rapid cooling and subsequent gradual cooling, (2) northward-younging of the timing of the rapid cooling, (3) gradual cooling followed by ca. 2 Myr rapid cooling in the frontmost part of the HHC nappe. The observed FT ages and paths were then compared with those predicted by forward thermokinematic modeling. The results of the thermokinematic modeling for the Flat-Ramp-Flat MHT model, in which the HHC and the underlying LHS are denudated accompanied with the movement of the Main Himalayan Thrust (MHT), well reproduced the observed paths and FT ages in eastern Nepal. This suggests that the observed FT ages and paths reflect a denudation process driven by the movement of the MHT showing the flat-ramp-flat geometry, and that the denudation rate and its spatial distribution have roughly been constant in eastern Nepal since ca. 9 Ma.
Hisadomi, Shohei*; Nakazawa, Kazuhiro*; Wada, Yuki*; Tsuji, Yuna*; Enoto, Teruaki*; Shinoda, Taro*; Morimoto, Takeshi*; Nakamura, Yoshitaka*; Yuasa, Takayuki*; Tsuchiya, Harufumi
Journal of Geophysical Research; Atmospheres, 126(18), p.e2021JD034543_1 - e2021JD034543_12, 2021/09
Times Cited Count：20 Percentile：77.40(Meteorology & Atmospheric Sciences)Kajino, Mizuo*; Adachi, Koji*; Igarashi, Yasuhito*; Satou, Yukihiko; Sawada, Morihiro*; Sekiyama, Tsuyoshi*; Zaizen, Yuji*; Saya, Akane*; Tsuruta, Haruo*; Moriguchi, Yuichi*
Journal of Geophysical Research; Atmospheres, 126(1), p.e2020JD033460_1 - e2020JD033460_23, 2021/01
Times Cited Count：15 Percentile：66.64(Meteorology & Atmospheric Sciences)Wada, Yuki*; Enoto, Teruaki*; Nakazawa, Kazuhiro*; Yuasa, Takayuki*; Furuta, Yoshihiro; Odaka, Hirokazu*; Makishima, Kazuo*; Tsuchiya, Harufumi
Journal of Geophysical Research; Atmospheres, 125(20), p.e2020JD033194_1 - e2020JD033194_15, 2020/10
Times Cited Count：4 Percentile：10.92(Meteorology & Atmospheric Sciences)Wada, Yuki*; Enoto, Teruaki*; Nakazawa, Kazuhiro*; Odaka, Hirokazu*; Furuta, Yoshihiro; Tsuchiya, Harufumi
Journal of Geophysical Research; Atmospheres, 125(20), p.e2020JD033193_1 - e2020JD033193_17, 2020/10
Times Cited Count：5 Percentile：15.21(Meteorology & Atmospheric Sciences)Wada, Yuki*; Enoto, Teruaki*; Nakamura, Yoshitaka*; Morimoto, Takeshi*; Sato, Mitsuteru*; Ushio, Tomoo*; Nakazawa, Kazuhiro*; Yuasa, Takayuki*; Yonetoku, Daisuke*; Sawano, Tatsuya*; et al.
Journal of Geophysical Research; Atmospheres, 125(4), p.e2019JD031730_1 - e2019JD031730_11, 2020/02
Times Cited Count：28 Percentile：78.32(Meteorology & Atmospheric Sciences)Usui, Yoichi*; Yamazaki, Toshitsugu*; Oka, Toshitaka; Kumagai Yuho*
Journal of Geophysical Research; Solid Earth, 124(11), p.10672 - 10686, 2019/11
Times Cited Count：6 Percentile：27.80(Geochemistry & Geophysics)We report the discovery of inverse AMS fabrics from pelagic clay recovered by a 
12 m long piston core from the western North Pacific. Rock magnetic data and ferromagnetic resonance spectroscopy indicated that magnetofossils account for most of the mean susceptibility regardless of normal or inverse AMS, suggesting that the inverse AMS fabrics due to magnetofossils may be widespread in pelagic clay.
Uchiyama, Yusuke*; Odani, Sachika*; Kashima, Motohiko*; Kamidaira, Yuki; Mitarai, Satoshi*
Journal of Geophysical Research; Oceans (Internet), 123(12), p.9245 - 9265, 2018/12
Times Cited Count：20 Percentile：69.43(Oceanography)no abstracts in English
Akiyoshi, Hideharu*; Kadowaki, Masanao; Nakamura, Haruna*; Sugita, Takafumi*; Hirooka, Toshihiko*; Harada, Yayoi*; Mizuno, Akira*
Journal of Geophysical Research; Atmospheres, 123(22), p.12523 - 12542, 2018/11
Times Cited Count：1 Percentile：2.33(Meteorology & Atmospheric Sciences)A reduction of the total ozone over the southern tip of South America lasting 3 weeks occurred in November 2009. Analyses of the ERA-Interim reanalysis data and the total ozone observed by the Ozone Monitoring Instrument indicate that the total ozone reduction event was caused by a migration of the polar vortex toward the South American continent at the time of the vortex breakup. The vortex migration is associated with an enhanced wave flux from the troposphere at 120-150
W and 50-60S to the west of the South American continent to the stratosphere over the southern part of the continent, which led to a large negative geopotential height anomaly in the lower stratosphere. In November, a blocking event was diagnosed from the 500-hPa geopotential height over the west of the South American continent. These results suggest a relation between the long-lasting reduction of the total ozone over the southern tip of South America and the blocking phenomenon in the troposphere of the Southern Hemisphere through wave propagation from the blocking region in 2009. Analysis of the total ozone anomaly for 50-60S and 65-75W over the southern tip of South America in November for 1979-2015 indicates that the negative ozone anomaly in November 2009 was one of the largest anomalies in this 37-year period and was associated with the large negative geopotential height anomaly in the lower stratosphere. Analyses of dynamical fields were also conducted for other years with large geopotential height anomalies.
Cs from the Fukushima Daiichi Nuclear Power Plant accident; Simulations based on identical input dataSato, Yosuke*; Takigawa, Masayuki*; Sekiyama, Tsuyoshi*; Kajino, Mizuo*; Terada, Hiroaki; Nagai, Haruyasu; Kondo, Hiroaki*; Uchida, Junya*; Goto, Daisuke*; Qu
lo, D.*; et al.
Journal of Geophysical Research; Atmospheres, 123(20), p.11748 - 11765, 2018/10
Times Cited Count：48 Percentile：84.77(Meteorology & Atmospheric Sciences)A model intercomparison of the atmospheric dispersion of Cs emitted following the Fukushima Daiichi Nuclear Power Plant accident was conducted by 12 models to understand the behavior of Cs in the atmosphere. The same meteorological data, horizontal grid resolution, and an emission inventory were applied to all the models to focus on the model variability originating from the processes included in each model. The multi-model ensemble captured 40% of the observed Cs events, and the figure-of-merit in space for the total deposition of Cs exceeded 80. Our analyses indicated that the meteorological data were most critical for reproducing the Cs events. The results also revealed that the differences among the models were originated from the deposition and diffusion processes when the meteorological field was simulated well. However, the models with strong diffusion tended to overestimate the Cs concentrations.
Cs plumes from the Fukushima Daiichi Nuclear Power Plant; Evaluation of the model intercomparison data of the Science Council of JapanKitayama, Kyo*; Morino, Yu*; Takigawa, Masayuki*; Nakajima, Teruyuki*; Hayami, Hiroshi*; Nagai, Haruyasu; Terada, Hiroaki; Saito, Kazuo*; Shimbori, Toshiki*; Kajino, Mizuo*; et al.
Journal of Geophysical Research; Atmospheres, 123(14), p.7754 - 7770, 2018/07
Times Cited Count：27 Percentile：66.99(Meteorology & Atmospheric Sciences)We compared seven atmospheric transport model results for Cs released during the Fukushima Daiichi Nuclear Power Plant accident. All the results had been submitted for a model intercomparison project of the Science Council of Japan in 2014. We assessed model performance by comparing model results with observed hourly atmospheric concentrations of Cs, focusing on nine plumes over the Tohoku and Kanto regions. The results showed that model performance for Cs concentrations was highly variable among models and plumes. We also assessed model performance for accumulated Cs deposition. Simulated areas of high deposition were consistent with the plume pathways, though the models that best simulated Cs concentrations were different from those that best simulated deposition. The ensemble mean of all models consistently reproduced Cs concentrations and deposition well, suggesting that use of a multimodel ensemble results in more effective and consistent model performance.
Kamidaira, Yuki; Uchiyama, Yusuke*; Kawamura, Hideyuki; Kobayashi, Takuya; Furuno, Akiko
Journal of Geophysical Research; Oceans (Internet), 123(4), p.2808 - 2828, 2018/04
Times Cited Count：25 Percentile：75.93(Oceanography)We developed a submesoscale eddy-resolving oceanic dispersal modeling system consisting of a double nested oceanic downscaling model and an offline oceanic radionuclides dispersion model to investigate influences of submesoscale coherent structures (SCSs) and associated ageostrophic secondary circulations (ASCs) on the three-dimensional (3D) dispersal and initial dilution of the dissolved radioactive Cs accidentally released from the Fukushima Daiichi Nuclear Power Plant (FNPP1) occurred since March 2011. The extensive model-data comparison demonstrates that the elaborated innermost high-resolution model at a lateral grid resolution of 1 km successfully reproduces transient mesoscale oceanic structures, the Kuroshio path and stratification, and spatiotemporal variations of 3D Cs concentrations. These SCSs and ASCs occurred primarily due to shear instability with baroclinic instability as the secondary mechanism, according to energy conversion and spectral analyses. The vertical Cs flux analysis was performed with decomposition of the variables into the mean, mesoscale, and submesoscale components using frequency and wavenumber filters. The vertical Cs flux analysis explained that 84% of the FNPP1-derived Cs was transported downward below the mixed layer by eddies, with the major contributions from ASCs induced by submesoscale eddies.
Sueoka, Shigeru; Ikeda, Yasutaka*; Kano, Kenichi*; Tsutsumi, Hiroyuki*; Tagami, Takahiro*; Kohn, B. P.*; Hasebe, Noriko*; Tamura, Akihiro*; Arai, Shoji*; Shibata, Kenji*
Journal of Geophysical Research; Solid Earth, 122(8), p.6787 - 6810, 2017/08
no abstracts in English
Sueoka, Shigeru; Shimada, Koji; Ishimaru, Tsuneari; Niwa, Masakazu; Yasue, Kenichi; Umeda, Koji*; Danhara, Toru*; Iwano, Hideki*
Journal of Geophysical Research; Solid Earth, 122(3), p.1848 - 1859, 2017/03
no abstracts in English
