Electromagnetic waves are a fundamental component of space plasma physics, enabling energy transport across different plasma regions and across scales. An important class of waves, observed throughout planetary plasma environments, are ultra-low frequency (ULF) waves (1 mHz to 1 Hz). These waves can be generated locally by instabilities or can be driven by changes in the solar wind conditions. In the inner magnetosphere, ULF waves are relevant for a range of plasma energies, from cold plasma to radiation belt populations.
ULF waves play an important role in accelerating and transporting electrons in planetary radiation belts and can modulate particle precipitation into the atmosphere. They can also serve as a diagnostic tool for local plasma characteristics as in the case of field line resonances and cyclotron waves. At Earth, enhanced ULF wave activity during magnetic storms can lead to harmful space weather effects. Understanding ULF wave physics is therefore crucial for space weather forecasting.
Major open questions in ULF wave physics include identifying the specific instability mechanism generating the waves, how the unstable plasma population is created, and when the waves are observed away from their source, what are the physical mechanisms responsible for their transmission. The large number of spacecraft operating in near-Earth space in the recent years, such as GOES, GEOTAIL, Cluster, THEMIS, the Van Allen Probes, MMS and Arase, combined with ground-based observatories such as the SuperMAG and the SuperDARN networks, now make it possible to study ULF wave activity from multiple vantage points. These missions also provide extended data sets enabling extensive statistical studies, to connect for example ULF wave activity with upstream solar wind conditions. These spacecraft further provide rich particle data which have yet to be fully digested for ULF wave physics. Complementing these multi-point observations, recent advances in numerical simulations bring new insight into wave generation and transmission.
While ULF waves are extensively studied at Earth, investigations at other solar system bodies are limited by the sparse data sets in these environments. Comparative studies of ULF waves in our solar system are warranted to evidence the differences and similarities of ULF wave properties in different planetary environments. The BepiColombo mission, with the upcoming Mercury flybys later this year, presents a great new opportunity to study ULF waves in the Hermean magnetosphere.
This Research Topic aims at gathering publications presenting recent advances in ULF wave physics in our solar system, including for example:
- detailed case studies of all types of ULF waves, such as Kelvin-Helmholtz waves, mirror modes, foreshock waves, field-line resonances, at Earth and other planets.
- statistical studies of ULF waves and their relationship with upstream conditions
- investigations of ULF wave transmission across different plasma regions, using for example multi-spacecraft data analysis and/or global simulations
- investigations of the impact of ULF waves on the surrounding plasma and their contribution to radiation belt dynamics
- comparative studies of ULF waves in different environments in our solar system
In addition to original research, we also invite reviews and perspectives addressing these topics.
Electromagnetic waves are a fundamental component of space plasma physics, enabling energy transport across different plasma regions and across scales. An important class of waves, observed throughout planetary plasma environments, are ultra-low frequency (ULF) waves (1 mHz to 1 Hz). These waves can be generated locally by instabilities or can be driven by changes in the solar wind conditions. In the inner magnetosphere, ULF waves are relevant for a range of plasma energies, from cold plasma to radiation belt populations.
ULF waves play an important role in accelerating and transporting electrons in planetary radiation belts and can modulate particle precipitation into the atmosphere. They can also serve as a diagnostic tool for local plasma characteristics as in the case of field line resonances and cyclotron waves. At Earth, enhanced ULF wave activity during magnetic storms can lead to harmful space weather effects. Understanding ULF wave physics is therefore crucial for space weather forecasting.
Major open questions in ULF wave physics include identifying the specific instability mechanism generating the waves, how the unstable plasma population is created, and when the waves are observed away from their source, what are the physical mechanisms responsible for their transmission. The large number of spacecraft operating in near-Earth space in the recent years, such as GOES, GEOTAIL, Cluster, THEMIS, the Van Allen Probes, MMS and Arase, combined with ground-based observatories such as the SuperMAG and the SuperDARN networks, now make it possible to study ULF wave activity from multiple vantage points. These missions also provide extended data sets enabling extensive statistical studies, to connect for example ULF wave activity with upstream solar wind conditions. These spacecraft further provide rich particle data which have yet to be fully digested for ULF wave physics. Complementing these multi-point observations, recent advances in numerical simulations bring new insight into wave generation and transmission.
While ULF waves are extensively studied at Earth, investigations at other solar system bodies are limited by the sparse data sets in these environments. Comparative studies of ULF waves in our solar system are warranted to evidence the differences and similarities of ULF wave properties in different planetary environments. The BepiColombo mission, with the upcoming Mercury flybys later this year, presents a great new opportunity to study ULF waves in the Hermean magnetosphere.
This Research Topic aims at gathering publications presenting recent advances in ULF wave physics in our solar system, including for example:
- detailed case studies of all types of ULF waves, such as Kelvin-Helmholtz waves, mirror modes, foreshock waves, field-line resonances, at Earth and other planets.
- statistical studies of ULF waves and their relationship with upstream conditions
- investigations of ULF wave transmission across different plasma regions, using for example multi-spacecraft data analysis and/or global simulations
- investigations of the impact of ULF waves on the surrounding plasma and their contribution to radiation belt dynamics
- comparative studies of ULF waves in different environments in our solar system
In addition to original research, we also invite reviews and perspectives addressing these topics.