Determining EMIC Wave Vector Properties Through Multi-Point Measurements: The Wave Curl Analysis

Area of Science:

• Space Physics
• Plasma Physics
• Magnetospheric Physics

Background:

• Electromagnetic ion cyclotron (EMIC) waves are significant drivers of particle loss in Earth's magnetosphere.
• Accurate knowledge of the wave vector (k) is essential for understanding EMIC wave propagation and wave-particle interactions.
• Previous methods for determining k have limitations, necessitating new observational techniques.

Purpose of the Study:

• To present and validate a novel observational technique for determining the wave vector (k) of EMIC waves.
• To leverage the unique multi-spacecraft capabilities of the Magnetospheric MultiScale (MMS) mission for wave analysis.
• To enable systematic studies of EMIC wave properties and their impact on magnetospheric dynamics.

Main Methods:

• Developed a wave curl analysis technique using the curl of the wave magnetic field to determine k.
• Applied the method to synthetic EMIC wave data with varying properties.
• Validated the technique using an observed EMIC wave event from MMS and compared results with WHAMP dispersion solutions and other multi-spacecraft methods.

Main Results:

• The wave curl analysis successfully determined the wave vector (k) for both synthetic and observed EMIC waves.
• Derived k values showed good agreement with WHAMP dispersion solutions and other observational techniques.
• The method demonstrated robustness when applied to wave intervals containing 3-4 wave periods across a wide frequency range.

Conclusions:

• The multi-spacecraft wave curl analysis provides a reliable method for directly determining EMIC wave vector properties.
• This technique enhances our ability to study EMIC wave propagation and wave-particle interactions in the magnetosphere.
• The MMS mission's instrumentation is well-suited for implementing this advanced wave analysis technique.