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  • Recommended articles
  • August 18, 2022

[Frontier Letter] Topside equatorial spread F-related field-aligned Poynting flux: observations and simulations

Equatorial spread F (ESF) occurs globally at low magnetic latitudes in the Earth’s nighttime ionosphere. ESF is well-known for its adverse effect on the propagation of radio waves affecting navigation, telecommunication, and scientific satellite systems. Due to scarce observations, the ESF’s electrodynamics has mainly been addressed theoretically. Rodríguez-Zuluaga et al. (2022) use satellite measurements and numerical simulations to report on ESF-related electromagnetic energy. The authors address the ESF energy’s magnitude… Read more

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  • October 28, 2021

[Frontier Letter] Wave–particle interaction effects in the Van Allen belts

When we gaze out on the distant universe, we see billions of galaxies and we also see hundreds of billions of stars in our own galaxy, the Milky Way. Whether we observe in the narrow wavelength band accessible to our human eyes, or we expand our vision to include radio, ultraviolet, x-ray, or gamma-ray domains, we see cosmic objects because they emit energetic photons. Such photons were mostly produced far… Read more

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  • October 26, 2021

[Frontier Letter] Physics-based secular variation candidate models for the IGRF

Fournier et al. (2021) report on physics-based secular variation forecasts for the international geomagnetic reference field (IGRF). Analysis of satellite data from 2000 onwards reveals that IGRF forecasts are worse at times of fast geomagnetic changes, which are due to processes occurring in the Earth’s fluid outer core. This calls for the implementation of  physics-based forecasting frameworks able to account for these fast changes. Fournier et al. (2021) discuss the… Read more

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  • October 26, 2021

[Frontier Letter] A quest for unrest in multiparameter observations at Whakaari/White Island volcano, NewZealand 2007–2018

Caudron et al. (2021) explores the seismic data associated with unrest and eruptions which occurred at Whakaari/White Island volcano in New Zealand for the last ~15 years. Using novel proxies taking advantage of continuous seismic records complemented by more traditional parameters (e.g., earthquakes, deformation), they gain insight into volcano-hydrothermal systems dynamics. Caudron et al. identifies various periods of unrest, shed light on the processes triggering them and overall appears promising for future… Read more

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  • August 16, 2021

[Frontier Letter] PSTEP: project for solar–terrestrial environment prediction

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, modern society supported by advanced information systems is at risk from severe space weather disturbances. Project for solar–terrestrial environment prediction (PSTEP) was launched to improve this situation through synergy between basic science research and operational forecast. The PSTEP is a nationwide research… Read more

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  • April 28, 2021

[Frontier Letter] Nonlinear wave growth theory of whistler-mode chorus and hiss emissions in the magnetosphere

Whistler-mode chorus and hiss waves controls dynamics of energetic electrons in the Earth’s magnetosphere. Omura (2021) describes nonlinear processes associated with the generation of chorus and hiss waves based on the theoretical developments in the past 15 years. The inhomogeneity factor due to the frequency variation and the gradient of the magnetic field plays a critical role in the generation process of rising-tone and falling-tone wave packets and associated electron… Read more

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  • April 22, 2021

[Frontier Letter] MOWLAS: NIED observation network for earthquake, tsunami and volcano

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 established since the 2011 Tohoku earthquake and tsunami as MOWLAS (Monitoring of Waves on Land and Seafloor) in November 2017. The purpose of MOWLAS is to provide comprehensive, accurate, and rapid observation and monitoring of earthquake, tsunami, and volcano events throughout Japan and its… Read more