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Frontier Letters

A Frontier letter is a letter on frontier research which is invited by the Editor-in-Chief. 

  1. Each International Geomagnetic Reference Field (IGRF) model released under the auspices of the International Association of Geomagnetism and Aeronomy comprises a secular variation component that describes the ...

    Authors: Alexandre Fournier, Julien Aubert, Vincent Lesur and Erwan Thébault

    Citation: Earth, Planets and Space 2021 73:190

    Content type: Frontier Letter

    Published on:

  2. Discovering such structures as the third radiation belt (or “storage ring”) has been a major observational achievement of the NASA Radiation Belt Storm Probes program (renamed the “Van Allen Probes” mission in...

    Authors: Daniel N. Baker

    Citation: Earth, Planets and Space 2021 73:189

    Content type: Frontier Letter

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  3. Although solar activity may significantly impact the global environment and socioeconomic systems, the mechanisms for solar eruptions and the subsequent processes have not yet been fully understood. Thus, mode...

    Authors: Kanya Kusano, Kiyoshi Ichimoto, Mamoru Ishii, Yoshizumi Miyoshi, Shigeo Yoden, Hideharu Akiyoshi, Ayumi Asai, Yusuke Ebihara, Hitoshi Fujiwara, Tada-Nori Goto, Yoichiro Hanaoka, Hisashi Hayakawa, Keisuke Hosokawa, Hideyuki Hotta, Kornyanat Hozumi, Shinsuke Imada…

    Citation: Earth, Planets and Space 2021 73:159

    Content type: Frontier Letter

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  4. Nonlinear processes associated with the generation process of whistler-mode chorus emissions are summarized. The nonlinear dynamics of energetic electrons interacting with a coherent whistler-mode wave and the...

    Authors: Yoshiharu Omura

    Citation: Earth, Planets and Space 2021 73:95

    Content type: Frontier Letter

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    The Correction to this article has been published in Earth, Planets and Space 2021 73:121

  5. National Research Institute for Earth Science and Disaster Resilience (NIED) integrated the land observation networks established since the 1995 Kobe earthquake with the seafloor observation networks establish...

    Authors: Shin Aoi, Youichi Asano, Takashi Kunugi, Takeshi Kimura, Kenji Uehira, Narumi Takahashi, Hideki Ueda, Katsuhiko Shiomi, Takumi Matsumoto and Hiroyuki Fujiwara

    Citation: Earth, Planets and Space 2020 72:126

    Content type: Frontier letter

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  6. Interferograms pertaining to large earthquakes typically reveal the occurrence of elastic deformations caused by the earthquake along with several complex surface displacements. In this study, we identified di...

    Authors: Satoshi Fujiwara, Takayuki Nakano and Yu Morishita

    Citation: Earth, Planets and Space 2020 72:119

    Content type: Frontier letter

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  10. Here, I review modern history of geodesy and geodynamics in Japan, highlighting a few episodes during the last two centuries. The review starts with the first measurement of the meridional arc length in Japan ...

    Authors: Kosuke Heki

    Citation: Earth, Planets and Space 2020 72:38

    Content type: Frontier letter

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  11. Observations by six Super Dual Auroral Radar Network (SuperDARN) polar cap radars, three in the northern hemisphere and three in the southern hemispheres, are considered to assess F region echo occurrence rate...

    Authors: Alexander V. Koustov, Sydney Ullrich, Pavlo V. Ponomarenko, Nozomu Nishitani, Federica M. Marcucci and William A. Bristow

    Citation: Earth, Planets and Space 2019 71:112

    Content type: Frontier letter

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  12. The Hokkaido Eastern Iburi Earthquake (M = 6.7) occurred on Sep. 6, 2018 in the southern part of Central Hokkaido, Japan. Since Paleogene, this region has experienced the dextral oblique transpression between the...

    Authors: Takaya Iwasaki, Noriko Tsumura, Tanio Ito, Kazunori Arita, Matsubara Makoto, Hiroshi Sato, Eiji Kurashimo, Naoshi Hirata, Susumu Abe, Katsuya Noda, Akira Fujiwara, Shinsuke Kikuchi and Kazuko Suzuki

    Citation: Earth, Planets and Space 2019 71:103

    Content type: Frontier letter

    Published on:

    The Correction to this article has been published in Earth, Planets and Space 2020 72:39

  13. The 2014–2015 eruption of the Nakadake first crater at Aso Volcano in southwestern Japan was characterized by continuous ash emissions and intermittent strombolian eruptions. In this paper, we present the dist...

    Authors: Yasuo Miyabuchi and Chihoko Hara

    Citation: Earth, Planets and Space 2019 71:44

    Content type: Frontier letter

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  14. Results from the first VHF profiler research radar in Costa Rica, operating at a central radar frequency of 46.6 MHz, are presented. Emphasis has been on studies of scattering layers detected in the altitude r...

    Authors: Marcial Garbanzo-Salas and Wayne Hocking

    Citation: Earth, Planets and Space 2019 71:6

    Content type: Frontier letter

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  16. Investigations of superchrons are the key to understanding long-term changes of the geodynamo and the mantle’s controlling role. Granitic rocks could be good recorders of deep-time geomagnetic field behavior, ...

    Authors: Chie Kato, Masahiko Sato, Yuhji Yamamoto, Hideo Tsunakawa and Joseph L. Kirschvink

    Citation: Earth, Planets and Space 2018 70:176

    Content type: Frontier letter

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  17. High-latitude, small-scale plasma density irregularities are observed by the Advanced Land Observation Satellite 2, Phase Array type L-band Synthetic Aperture Radar-2 and the European Incoherent Scatter radar ...

    Authors: Hiroatsu Sato, Jun Su Kim, Norbert Jakowski and Ingemar Häggström

    Citation: Earth, Planets and Space 2018 70:163

    Content type: Frontier letter

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  19. A simple and rapid technique to effectively remove volcanic smoke (vapor-dominated white plume) from visible or thermal infrared images of active craters is proposed, in which multiple photographs taken in a f...

    Authors: Takeshi Hashimoto, Akihiko Terada and Ryo Tanaka

    Citation: Earth, Planets and Space 2018 70:109

    Content type: Frontier letter

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  20. The uppermost structures of incoming oceanic plates have been investigated by seismic exploration surveys, primarily based on two-dimensional profiles. However, their regional-scale lateral variations and shea...

    Authors: Takashi Tonegawa, Koichiro Obana, Gou Fujie and Shuichi Kodaira

    Citation: Earth, Planets and Space 2018 70:106

    Content type: Frontier letter

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  22. A hot and acid crater lake is located in the Nakadake crater, Aso volcano, Japan. The volume of water in the lake decreases with increasing activity, drying out prior to the magmatic eruptions. Salt-rich mater...

    Authors: Hiroshi Shinohara, Nobuo Geshi, Akihiko Yokoo, Takahiro Ohkura and Akihiko Terada

    Citation: Earth, Planets and Space 2018 70:46

    Content type: Frontier letter

    Published on:

  23. The first year (December 2015 to November 2016) of IR2 after Akatsuki’s successful insertion to an elongated elliptical orbit around Venus is reported with performance evaluation and results of data acquisitio...

    Authors: Takehiko Satoh, Takao M. Sato, Masato Nakamura, Yasumasa Kasaba, Munetaka Ueno, Makoto Suzuki, George L. Hashimoto, Takeshi Horinouchi, Takeshi Imamura, Atsushi Yamazaki, Takayuki Enomoto, Yuri Sakurai, Kosuke Takami, Kenta Sawai, Takashi Nakakushi, Takumi Abe…

    Citation: Earth, Planets and Space 2017 69:154

    Content type: Frontier Letter

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  24. We report on the large-scale evolution of dipolarization in the near-Earth plasma sheet during an intense (AL ~ −1000 nT) substorm on August 10, 2016, when multiple spacecraft at radial distances between 4 and...

    Authors: Rumi Nakamura, Tsugunobu Nagai, Joachim Birn, Victor A. Sergeev, Olivier Le Contel, Ali Varsani, Wolfgang Baumjohann, Takuma Nakamura, Sergey Apatenkov, Anton Artemyev, Robert E. Ergun, Stephen A. Fuselier, Daniel J. Gershman, Barbara J. Giles, Yuri V. Khotyaintsev, Per-Arne Lindqvist…

    Citation: Earth, Planets and Space 2017 69:129

    Content type: Frontier Letter

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  25. Jupiter’s moon Io, which orbits deep inside the magnetosphere, is the most geologically active object in the solar system. Kurdalagon Patera, a volcano on Io, erupted in 2015 and became a substantial source of...

    Authors: Ichiro Yoshikawa, Fumiharu Suzuki, Reina Hikida, Kazuo Yoshioka, Go Murakami, Fuminori Tsuchiya, Chihiro Tao, Atsushi Yamazaki, Tomoki Kimura, Hajime Kita, Hiromasa Nozawa and Masaki Fujimoto

    Citation: Earth, Planets and Space 2017 69:110

    Content type: Frontier Letter

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  26. A laser strainmeter with a 1500-m baseline was constructed at an underground site in Kamioka, Gifu Prefecture, Japan, and has been operating since August 2016. The laser interferometer measures the change in d...

    Authors: Akito Araya, Akiteru Takamori, Wataru Morii, Kouseki Miyo, Masatake Ohashi, Kazuhiro Hayama, Takashi Uchiyama, Shinji Miyoki and Yoshio Saito

    Citation: Earth, Planets and Space 2017 69:77

    Content type: Frontier letter

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  28. A simple and efficient finite-difference scheme is developed to calculate seismic wave propagation in a partial spherical shell model of a three-dimensionally (3-D) heterogeneous global Earth structure for mod...

    Authors: Hiroshi Takenaka, Masanao Komatsu, Genti Toyokuni, Takeshi Nakamura and Taro Okamoto

    Citation: Earth, Planets and Space 2017 69:67

    Content type: Frontier letter

    Published on:

  29. This study develops a three-dimensional viscoelastic model using the finite element method to understand the postseismic deformation that followed the 2011 Tohoku-Oki earthquake. The question of understanding ...

    Authors: Hisashi Suito

    Citation: Earth, Planets and Space 2017 69:21

    Content type: Frontier letter

    Published on:

    The Erratum to this article has been published in Earth, Planets and Space 2017 69:55