Canonical Electromagnetic Observables for Systematic Characterization of Electric and Magnetic Wave Field Data on board Spacecraft

TL;DR

This paper introduces Canonical Electromagnetic Observables (CEO), a covariant tensor-based data format for analyzing spacecraft electromagnetic wave data, providing physically meaningful measures like energy density and Poynting flux.

Contribution

The paper presents a new tensor-based characterization of electromagnetic wave data that offers a physically interpretable alternative to traditional data arrays on spacecraft.

Findings

Successfully applied to chorus emission data from Cluster-II spacecraft

Provides a set of physical observables including energy density and Poynting flux

Enhances analysis of electromagnetic wave phenomena in space environments

Abstract

We present a new characterization of partially coherent electric and magnetic wave vector fields.This characterization is based on the 36 auto/cross correlations of the 3+3 complex Cartesian components of the electric and magnetic wave fields and is particularly suited for analyzing electromagnetic wave data on board spacecraft. Data from spacecraft based electromagnetic wave instruments are usually processed as data arrays. These data arrays however do not have a physical interpretation in themselves; they are simply a convenient storage format. In contrast, the characterization proposed here contains exactly the same information but are in the form of manifestly covariant space-time tensors. We call this data format the Canonical Electromagnetic Observables (CEO) since they correspond to unique physical observables. Some of them are already known, such as energy density, Poynting flux, stress tensor, etc, while others should be relevant in future space research. As an example we use this formalism to analyze data from a chorus emission in the mid-latitude magnetosphere, as recorded by the STAFF-SA instrument on board the Cluster-II spacecraft.