A statistical study of EMIC waves observed by Cluster: 1. Wave properties

• Published in: Journal of geophysical research. Space physics Vol. 120; no. 7; pp. 5574 - 5592
• Main Authors: Allen, R. C., Zhang, J.-C., Kistler, L. M., Spence, H. E., Lin, R.-L., Klecker, B., Dunlop, M. W., André, M., Jordanova, V. K.
• Format: Journal Article
• Language: English
• Published: Washington Blackwell Publishing Ltd 01-07-2015
• Subjects: Activation; Cluster; Clusters; Cyclotrons; Ellipticity; EMIC waves; Equator; Ion cyclotron waves; Magnetosphere; Magnetospheres; Particle dynamics; Polar orbits; Propagation; Properties (attributes); Shabansky orbits; Statistical analysis; Studies; Wave generation; Wave power; Wave propagation
• ISSN: 2169-9380; 2169-9402; 2169-9402
• DOI: 10.1002/2015JA021333

Electromagnetic ion cyclotron (EMIC) waves are an important mechanism for particle energization and losses inside the magnetosphere. In order to better understand the effects of these waves on particle dynamics, detailed information about the occurrence rate, wave power, ellipticity, normal angle, energy propagation angle distributions, and local plasma parameters are required. Previous statistical studies have used in situ observations to investigate the distribution of these parameters in the magnetic local time versus L‐shell (MLT‐L) frame within a limited magnetic latitude (MLAT) range. In this study, we present a statistical analysis of EMIC wave properties using 10 years (2001–2010) of data from Cluster, totaling 25,431 min of wave activity. Due to the polar orbit of Cluster, we are able to investigate EMIC waves at all MLATs and MLTs. This allows us to further investigate the MLAT dependence of various wave properties inside different MLT sectors and further explore the effects of Shabansky orbits on EMIC wave generation and propagation. The statistical analysis is presented in two papers. This paper focuses on the wave occurrence distribution as well as the distribution of wave properties. The companion paper focuses on local plasma parameters during wave observations as well as wave generation proxies.
Key Points
A statistical study of EMIC waves is conducted over all MLATs and MLTs
Off‐equator peaks in wave occurrence are observed in the outer magnetosphere
Wave ellipticity, normal angle, propagation angle, and wave power are also investigated