Articles | Volume 33, issue 8
https://doi.org/10.5194/angeo-33-941-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/angeo-33-941-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
A case study on generation mechanisms of a sporadic sodium layer above Tromsø (69.6° N) during a night of high auroral activity
T. Takahashi
CORRESPONDING AUTHOR
Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
Center for Space Science and Radio Engineering, The University of Electro-communications, Chofu, Tokyo
S. Nozawa
Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
T. T. Tsuda
Department of Communication Engineering and Informatics, The University of Electro-communications, Chofu, Tokyo
National Institute of Polar Research, Tachikawa, Tokyo, Japan
Y. Ogawa
National Institute of Polar Research, Tachikawa, Tokyo, Japan
Graduate University for Advanced Studies, Tokyo, Japan
N. Saito
RIKEN Center for Advanced Photonics, RIKEN, Wako, Saitama, Japan
T. Hidemori
Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
T. D. Kawahara
Faculty of Engineering, Shinshu University, Nagano, Nagano, Japan
C. Hall
Tromsø Geophysical Observatory, The Arctic University of Tromsø, Tromsø, Norway
H. Fujiwara
Faculty of Science and Technology, Seikei University, Musashino, Tokyo, Japan
N. Matuura
Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
A. Brekke
Faculty of Science, The Arctic University of Tromsø, Tromsø, Norway
M. Tsutsumi
National Institute of Polar Research, Tachikawa, Tokyo, Japan
Graduate University for Advanced Studies, Tokyo, Japan
S. Wada
RIKEN Center for Advanced Photonics, RIKEN, Wako, Saitama, Japan
T. Kawabata
Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
S. Oyama
Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
R. Fujii
Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan
Related authors
Viswanathan Lakshmi Narayanan, Satonori Nozawa, Shin-Ichiro Oyama, Ingrid Mann, Kazuo Shiokawa, Yuichi Otsuka, Norihito Saito, Satoshi Wada, Takuya D. Kawahara, and Toru Takahashi
Atmos. Chem. Phys., 21, 2343–2361, https://doi.org/10.5194/acp-21-2343-2021, https://doi.org/10.5194/acp-21-2343-2021, 2021
Short summary
Short summary
In the past, additional sodium peaks occurring above the main sodium layer of the upper mesosphere were discussed. Here, formation of an additional sodium peak below the main sodium layer peak is discussed in detail. The event coincided with passage of multiple mesospheric bores, which are step-like disturbances occurring in the upper mesosphere. Hence, this work highlights the importance of such mesospheric bores in causing significant changes to the minor species concentration in a short time.
T. Takahashi, S. Nozawa, M. Tsutsumi, C. Hall, S. Suzuki, T. T. Tsuda, T. D. Kawahara, N. Saito, S. Oyama, S. Wada, T. Kawabata, H. Fujiwara, A. Brekke, A. Manson, C. Meek, and R. Fujii
Ann. Geophys., 32, 1195–1205, https://doi.org/10.5194/angeo-32-1195-2014, https://doi.org/10.5194/angeo-32-1195-2014, 2014
Sota Nanjo, Masatoshi Yamauchi, Magnar Gullikstad Johnsen, Yoshihiro Yokoyama, Urban Brändström, Yasunobu Ogawa, Anna Naemi Willer, and Keisuke Hosokawa
EGUsphere, https://doi.org/10.5194/egusphere-2024-3277, https://doi.org/10.5194/egusphere-2024-3277, 2024
Short summary
Short summary
Our research explored the "shock aurora," caused by the impact of solar wind particles on Earth's magnetic field. On February 26, 2023, we observed this rare event on the nightside, where such observations are difficult. Ground-based cameras revealed new structural features, including undulating and jumping patterns. These results provide fresh insights into the complex interactions between the solar wind and Earth's magnetosphere, enhancing our understanding of space weather effects.
Arthur Gauthier, Claudia Borries, Alexander Kozlovsky, Diego Janches, Peter Brown, Denis Vida, Christoph Jacobi, Damian Murphy, Masaki Tsutsumi, Njål Gulbrandsen, Satonori Nozawa, Mark Lester, Johan Kero, Nicholas Mitchell, Tracy Moffat-Griffin, and Gunter Stober
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2024-13, https://doi.org/10.5194/angeo-2024-13, 2024
Revised manuscript under review for ANGEO
Short summary
Short summary
This study focuses on the TIMED Doppler Interferometer (TIDI)-Meteor Radar(MR) comparison of zonal and meridional winds and their dependence on local time and latitude. The correlation calculation between TIDI winds measurements and MR winds shows good agreement. A TIDI-MR seasonal comparison and the altitude-latitude dependence for winds is performed. TIDI reproduce the mean circulation well when compared with the MRs and might be useful as a lower boundary for general circulation models.
Tinna L. Gunnarsdottir, Ingrid Mann, Wuhu Feng, Devin R. Huyghebaert, Ingemar Haeggstroem, Yasunobu Ogawa, Norihito Saito, Satonori Nozawa, and Takuya D. Kawahara
Ann. Geophys., 42, 213–228, https://doi.org/10.5194/angeo-42-213-2024, https://doi.org/10.5194/angeo-42-213-2024, 2024
Short summary
Short summary
Several tons of meteoric particles burn up in our atmosphere each day. This deposits a great deal of material that binds with other atmospheric particles and forms so-called meteoric smoke particles. These particles are assumed to influence radar measurements. Here, we have compared radar measurements with simulations of a radar spectrum with and without dust particles and found that dust influences the radar spectrum in the altitude range of 75–85 km.
Yoshimasa Tanaka, Yasunobu Ogawa, Akira Kadokura, Takehiko Aso, Björn Gustavsson, Urban Brändström, Tima Sergienko, Genta Ueno, and Satoko Saita
Ann. Geophys., 42, 179–190, https://doi.org/10.5194/angeo-42-179-2024, https://doi.org/10.5194/angeo-42-179-2024, 2024
Short summary
Short summary
We present via simulation how useful monochromatic images taken by a multi-point imager network are for auroral research in the EISCAT_3D project. We apply the generalized-aurora computed tomography (G-ACT) to modeled multiple auroral images and ionospheric electron density data. It is demonstrated that G-ACT provides better reconstruction results than the normal ACT and can interpolate ionospheric electron density at a much higher spatial resolution than observed by the EISCAT_3D radar.
Gunter Stober, Sharon L. Vadas, Erich Becker, Alan Liu, Alexander Kozlovsky, Diego Janches, Zishun Qiao, Witali Krochin, Guochun Shi, Wen Yi, Jie Zeng, Peter Brown, Denis Vida, Neil Hindley, Christoph Jacobi, Damian Murphy, Ricardo Buriti, Vania Andrioli, Paulo Batista, John Marino, Scott Palo, Denise Thorsen, Masaki Tsutsumi, Njål Gulbrandsen, Satonori Nozawa, Mark Lester, Kathrin Baumgarten, Johan Kero, Evgenia Belova, Nicholas Mitchell, Tracy Moffat-Griffin, and Na Li
Atmos. Chem. Phys., 24, 4851–4873, https://doi.org/10.5194/acp-24-4851-2024, https://doi.org/10.5194/acp-24-4851-2024, 2024
Short summary
Short summary
On 15 January 2022, the Hunga Tonga-Hunga Ha‘apai volcano exploded in a vigorous eruption, causing many atmospheric phenomena reaching from the surface up to space. In this study, we investigate how the mesospheric winds were affected by the volcanogenic gravity waves and estimated their propagation direction and speed. The interplay between model and observations permits us to gain new insights into the vertical coupling through atmospheric gravity waves.
Mizuki Fukizawa, Yoshimasa Tanaka, Yasunobu Ogawa, Keisuke Hosokawa, Tero Raita, and Kirsti Kauristie
Ann. Geophys., 41, 511–528, https://doi.org/10.5194/angeo-41-511-2023, https://doi.org/10.5194/angeo-41-511-2023, 2023
Short summary
Short summary
We use computed tomography to reconstruct the three-dimensional distributions of the Hall and Pedersen conductivities of pulsating auroras, a key research target for understanding the magnetosphere–ionosphere coupling process. It is suggested that the high-energy electron precipitation associated with pulsating auroras may have a greater impact on the closure of field-aligned currents in the ionosphere than has been previously reported.
Florian Günzkofer, Dimitry Pokhotelov, Gunter Stober, Ingrid Mann, Sharon L. Vadas, Erich Becker, Anders Tjulin, Alexander Kozlovsky, Masaki Tsutsumi, Njål Gulbrandsen, Satonori Nozawa, Mark Lester, Evgenia Belova, Johan Kero, Nicholas J. Mitchell, and Claudia Borries
Ann. Geophys., 41, 409–428, https://doi.org/10.5194/angeo-41-409-2023, https://doi.org/10.5194/angeo-41-409-2023, 2023
Short summary
Short summary
Gravity waves (GWs) are waves in Earth's atmosphere and can be observed as cloud ripples. Under certain conditions, these waves can propagate up into the ionosphere. Here, they can cause ripples in the ionosphere plasma, observable as oscillations of the plasma density. Therefore, GWs contribute to the ionospheric variability, making them relevant for space weather prediction. Additionally, the behavior of these waves allows us to draw conclusions about the atmosphere at these altitudes.
Nobuo Matuura, Ryoichi Fujii, and Satonori Nozawa
Hist. Geo Space. Sci., 14, 61–69, https://doi.org/10.5194/hgss-14-61-2023, https://doi.org/10.5194/hgss-14-61-2023, 2023
Short summary
Short summary
This paper describes the details of the Japan's participation in the EISCAT Radar Scientific Association as the 7th associate country approved in 1995, emphasizing strong collaboration with Norwegian scientists and the EISCAT Radar Scientific Association towards the realization of the Svalbard second antenna. Also described is a brief summary of Japanese EISCAT-related scientific achievement, comprehensive scientific collaborations so far between Japan and Europe, and hopes for EISCAT_3D.
Gunter Stober, Alan Liu, Alexander Kozlovsky, Zishun Qiao, Witali Krochin, Guochun Shi, Johan Kero, Masaki Tsutsumi, Njål Gulbrandsen, Satonori Nozawa, Mark Lester, Kathrin Baumgarten, Evgenia Belova, and Nicholas Mitchell
Ann. Geophys., 41, 197–208, https://doi.org/10.5194/angeo-41-197-2023, https://doi.org/10.5194/angeo-41-197-2023, 2023
Short summary
Short summary
The Hunga Tonga–Hunga Ha‘apai volcanic eruption was one of the most vigorous volcanic explosions in the last centuries. The eruption launched many atmospheric waves traveling around the Earth. In this study, we identify these volcanic waves at the edge of space in the mesosphere/lower-thermosphere, leveraging wind observations conducted with multi-static meteor radars in northern Europe and with the Chilean Observation Network De Meteor Radars (CONDOR).
Yuan Xia, Jing Jiao, Satonori Nozawa, Xuewu Cheng, Jihong Wang, Chunhua Shi, Lifang Du, Yajuan Li, Haoran Zheng, Faquan Li, and Guotao Yang
Atmos. Chem. Phys., 22, 13817–13831, https://doi.org/10.5194/acp-22-13817-2022, https://doi.org/10.5194/acp-22-13817-2022, 2022
Short summary
Short summary
The layer of sodium atoms is generally located above 80 km. This study reports the significant enhancements of the sodium layer below 75 km where sodium atoms are short-lived. The neutral chemical reactions were suggested as making a critical contribution. The reported results provide clear observational evidence for the role of planetary waves in the variation of metal layers, and have implications for the response of the metal layers to perturbations in the lower atmosphere.
Gunter Stober, Alan Liu, Alexander Kozlovsky, Zishun Qiao, Ales Kuchar, Christoph Jacobi, Chris Meek, Diego Janches, Guiping Liu, Masaki Tsutsumi, Njål Gulbrandsen, Satonori Nozawa, Mark Lester, Evgenia Belova, Johan Kero, and Nicholas Mitchell
Atmos. Meas. Tech., 15, 5769–5792, https://doi.org/10.5194/amt-15-5769-2022, https://doi.org/10.5194/amt-15-5769-2022, 2022
Short summary
Short summary
Precise and accurate measurements of vertical winds at the mesosphere and lower thermosphere are rare. Although meteor radars have been used for decades to observe horizontal winds, their ability to derive reliable vertical wind measurements was always questioned. In this article, we provide mathematical concepts to retrieve mathematically and physically consistent solutions, which are compared to the state-of-the-art non-hydrostatic model UA-ICON.
Mizuki Fukizawa, Takeshi Sakanoi, Yoshimasa Tanaka, Yasunobu Ogawa, Keisuke Hosokawa, Björn Gustavsson, Kirsti Kauristie, Alexander Kozlovsky, Tero Raita, Urban Brändström, and Tima Sergienko
Ann. Geophys., 40, 475–484, https://doi.org/10.5194/angeo-40-475-2022, https://doi.org/10.5194/angeo-40-475-2022, 2022
Short summary
Short summary
The pulsating auroral generation mechanism has been investigated by observing precipitating electrons using rockets or satellites. However, it is difficult for such observations to distinguish temporal changes from spatial ones. In this study, we reconstructed the horizontal 2-D distribution of precipitating electrons using only auroral images. The 3-D aurora structure was also reconstructed. We found that there were both spatial and temporal changes in the precipitating electron energy.
Fasil Tesema, Noora Partamies, Daniel K. Whiter, and Yasunobu Ogawa
Ann. Geophys., 40, 1–10, https://doi.org/10.5194/angeo-40-1-2022, https://doi.org/10.5194/angeo-40-1-2022, 2022
Short summary
Short summary
In this study, we present the comparison between an auroral model and EISCAT radar electron densities during pulsating aurorae. We test whether an overpassing satellite measurement of the average energy spectrum is a reasonable estimate for pulsating aurora electron precipitation. When patchy pulsating aurora is dominant in the morning sector, the overpass-averaged spectrum is found to be a reasonable estimate – but not when there is a mix of pulsating aurora types in the post-midnight sector.
Gunter Stober, Alexander Kozlovsky, Alan Liu, Zishun Qiao, Masaki Tsutsumi, Chris Hall, Satonori Nozawa, Mark Lester, Evgenia Belova, Johan Kero, Patrick J. Espy, Robert E. Hibbins, and Nicholas Mitchell
Atmos. Meas. Tech., 14, 6509–6532, https://doi.org/10.5194/amt-14-6509-2021, https://doi.org/10.5194/amt-14-6509-2021, 2021
Short summary
Short summary
Wind observations at the edge to space, 70–110 km altitude, are challenging. Meteor radars have become a widely used instrument to obtain mean wind profiles above an instrument for these heights. We describe an advanced mathematical concept and present a tomographic analysis using several meteor radars located in Finland, Sweden and Norway, as well as Chile, to derive the three-dimensional flow field. We show an example of a gravity wave decelerating the mean flow.
Pekka T. Verronen, Antti Kero, Noora Partamies, Monika E. Szeląg, Shin-Ichiro Oyama, Yoshizumi Miyoshi, and Esa Turunen
Ann. Geophys., 39, 883–897, https://doi.org/10.5194/angeo-39-883-2021, https://doi.org/10.5194/angeo-39-883-2021, 2021
Short summary
Short summary
This paper is the first to simulate and analyse the pulsating aurorae impact on middle atmosphere on monthly/seasonal timescales. We find that pulsating aurorae have the potential to make a considerable contribution to the total energetic particle forcing and increase the impact on upper stratospheric odd nitrogen and ozone in the polar regions. Thus, it should be considered in atmospheric and climate simulations.
Joel P. Younger, Iain M. Reid, Chris L. Adami, Chris M. Hall, and Masaki Tsutsumi
Atmos. Meas. Tech., 14, 5015–5027, https://doi.org/10.5194/amt-14-5015-2021, https://doi.org/10.5194/amt-14-5015-2021, 2021
Short summary
Short summary
A radar in Svalbard usually used to study meteor trails was used to observe a thin icy layer in the upper atmosphere. New methods used the layer to measure wind speed over short periods of time and found that the layer is most reflective within 6.8 ± 3.3° of vertical. Analysis of meteor trail radar echo durations found that the layer may shorten meteor trail echoes, but more data are needed. This study shows new uses for data collected by meteor radars for other purposes.
Viswanathan Lakshmi Narayanan, Satonori Nozawa, Shin-Ichiro Oyama, Ingrid Mann, Kazuo Shiokawa, Yuichi Otsuka, Norihito Saito, Satoshi Wada, Takuya D. Kawahara, and Toru Takahashi
Atmos. Chem. Phys., 21, 2343–2361, https://doi.org/10.5194/acp-21-2343-2021, https://doi.org/10.5194/acp-21-2343-2021, 2021
Short summary
Short summary
In the past, additional sodium peaks occurring above the main sodium layer of the upper mesosphere were discussed. Here, formation of an additional sodium peak below the main sodium layer peak is discussed in detail. The event coincided with passage of multiple mesospheric bores, which are step-like disturbances occurring in the upper mesosphere. Hence, this work highlights the importance of such mesospheric bores in causing significant changes to the minor species concentration in a short time.
Asgeir Brekke
Hist. Geo Space. Sci., 12, 1–9, https://doi.org/10.5194/hgss-12-1-2021, https://doi.org/10.5194/hgss-12-1-2021, 2021
Short summary
Short summary
A historical review of the establishment of the Haldde Observatory in Bossekop, Kaafjord, Finnmark, in northern Norway is presented together with some of the scientific outcomes of the efforts and the aftermath of this enterprise that led to the establishment of the University of Tromsø in 1968 and finally the inauguration of the Haldde Observatory as a historic site by the European Physical Society in 2018.
Philippe Baron, Satoshi Ochiai, Eric Dupuy, Richard Larsson, Huixin Liu, Naohiro Manago, Donal Murtagh, Shin-ichiro Oyama, Hideo Sagawa, Akinori Saito, Takatoshi Sakazaki, Masato Shiotani, and Makoto Suzuki
Atmos. Meas. Tech., 13, 219–237, https://doi.org/10.5194/amt-13-219-2020, https://doi.org/10.5194/amt-13-219-2020, 2020
Short summary
Short summary
Submillimeter-Wave Limb-Emission Sounder 2 (SMILES-2) is a satellite mission proposed in Japan to probe the middle and upper atmosphere (20–160 km). The key products are wind, temperature and density. If selected, this mission could provide new insights into vertical coupling in the atmosphere and could help improve weather and climate models. We conducted simulation studies to assess the measurement performances in the altitude range 60–110 km, with a special focus on the geomagnetic effects.
Wen Yi, Xianghui Xue, Iain M. Reid, Damian J. Murphy, Chris M. Hall, Masaki Tsutsumi, Baiqi Ning, Guozhu Li, Robert A. Vincent, Jinsong Chen, Jianfei Wu, Tingdi Chen, and Xiankang Dou
Atmos. Chem. Phys., 19, 7567–7581, https://doi.org/10.5194/acp-19-7567-2019, https://doi.org/10.5194/acp-19-7567-2019, 2019
Short summary
Short summary
The seasonal variations in the mesopause densities, especially with regard to its global structure, are still unclear. In this study, we report the climatology of the mesopause density estimated using multiyear observations from nine meteor radars from Arctic to Antarctic latitudes. The results reveal a significant AO and SAO in mesopause density, an asymmetry between the two polar regions and evidence of intraseasonal oscillations (ISOs), perhaps associated with the ISOs of the troposphere.
Takuo T. Tsuda, Yuta Hozumi, Kento Kawaura, Keisuke Hosokawa, Hidehiko Suzuki, and Takuji Nakamura
Atmos. Meas. Tech., 11, 6163–6168, https://doi.org/10.5194/amt-11-6163-2018, https://doi.org/10.5194/amt-11-6163-2018, 2018
Short summary
Short summary
Polar mesospheric clouds (PMCs) or noctilucent clouds (NLCs) are the highest clouds in the Earth's atmosphere. In this paper, we introduce new PMC observations by the Japanese Geostationary Earth Orbit (GEO) meteorological satellite Himawari-8, which was launched in October 2014.
Nickolay Ivchenko, Nicola M. Schlatter, Hanna Dahlgren, Yasunobu Ogawa, Yuka Sato, and Ingemar Häggström
Ann. Geophys., 35, 1143–1149, https://doi.org/10.5194/angeo-35-1143-2017, https://doi.org/10.5194/angeo-35-1143-2017, 2017
Short summary
Short summary
Photo-electrons and secondary electrons from particle precipitation enhance the incoherent scatter plasma line to levels sufficient for detection. A plasma line gives an accurate measure of the electron density and can be used to estimate electron temperature. The occurrence of plasma line enhancements in the EISCAT Svalbard Radar data was investigated. During summer daytime hours the plasma line is detectable in up to 90 % of the data. In winter time the occurrence is a few percent.
Chris M. Hall
Nonlin. Processes Geophys., 23, 215–222, https://doi.org/10.5194/npg-23-215-2016, https://doi.org/10.5194/npg-23-215-2016, 2016
Short summary
Short summary
The relative ionospheric opacity meter ("riometer") is a traditional instrument for measuring the degree to which cosmic noise is absorbed by the ionosphere and therefore how energetic the particles – electrons, protons etc. – are that cause the ionisation. We identify the same signatures in the "hour-to-days" timescale variability as reported in solar and geomagnetic disturbances. The result demonstrates the relationship between riometer data and the underlying physics for different timescales.
Silje Eriksen Holmen, Chris M. Hall, and Masaki Tsutsumi
Atmos. Chem. Phys., 16, 7853–7866, https://doi.org/10.5194/acp-16-7853-2016, https://doi.org/10.5194/acp-16-7853-2016, 2016
Short summary
Short summary
Atmospheric temperatures at 90 km height above Tromsø, Norway, from 2003 to 2014 have been determined using meteor radar. Periodic oscillations ranging from ~ 9 days to a year were found in the dataset, which were related to the large-scale circulation in the middle atmosphere and with wave activity. A trend analysis was performed, revealing an overall weak cooling trend from 2003 to 2014, which is in line with other recent studies on mesopause region (~ 90 km) temperature trends.
Chris M. Hall, Silje E. Holmen, Chris E. Meek, Alan H. Manson, and Satonori Nozawa
Atmos. Chem. Phys., 16, 2299–2308, https://doi.org/10.5194/acp-16-2299-2016, https://doi.org/10.5194/acp-16-2299-2016, 2016
Short summary
Short summary
Turbulent energy dissipation rates are calculated using MF-radar signals from 70 and 52° N for the period 2001–2014 inclusive, and they are used to estimate turbopause altitudes. A positive trend in turbopause altitude is identified for 70° N in summer, but not in winter and not at 52° N. The turbopause altitude change between 2001 and 2014 can be used to hypothesize a corresponding change in atomic oxygen concentration.
T. Ishida, Y. Ogawa, A. Kadokura, K. Hosokawa, and Y. Otsuka
Ann. Geophys., 33, 525–530, https://doi.org/10.5194/angeo-33-525-2015, https://doi.org/10.5194/angeo-33-525-2015, 2015
Short summary
Short summary
We studied the localized plasma density enhancements called blobs, which are often produced in the high-latitude ionosphere by the transportation process of plasma or particle precipitations. This subject is important because such structures affect radio wave propagation and can cause scintillation of GNSS signals in the deformation process. This paper is the first report of direct observations of blob deformation during a substorm.
C. M. Hall
Nonlin. Processes Geophys., 21, 1051–1058, https://doi.org/10.5194/npg-21-1051-2014, https://doi.org/10.5194/npg-21-1051-2014, 2014
T. Takahashi, S. Nozawa, M. Tsutsumi, C. Hall, S. Suzuki, T. T. Tsuda, T. D. Kawahara, N. Saito, S. Oyama, S. Wada, T. Kawabata, H. Fujiwara, A. Brekke, A. Manson, C. Meek, and R. Fujii
Ann. Geophys., 32, 1195–1205, https://doi.org/10.5194/angeo-32-1195-2014, https://doi.org/10.5194/angeo-32-1195-2014, 2014
H. Fujiwara, S. Nozawa, Y. Ogawa, R. Kataoka, Y. Miyoshi, H. Jin, and H. Shinagawa
Ann. Geophys., 32, 831–839, https://doi.org/10.5194/angeo-32-831-2014, https://doi.org/10.5194/angeo-32-831-2014, 2014
H. Suzuki, T. Nakamura, M. K. Ejiri, T. Ogawa, M. Tsutsumi, M. Abo, T. D. Kawahara, Y. Tomikawa, A. S. Yukimatu, and N. Sato
Ann. Geophys., 31, 1793–1803, https://doi.org/10.5194/angeo-31-1793-2013, https://doi.org/10.5194/angeo-31-1793-2013, 2013