Magnetosheath plasma stability and ULF wave occurrence as a function of location in the magnetosheath and upstream bow shock parameters

0444516 - ÚFA 2016 RIV US eng J - Journal Article
Souček, Jan - Escoubet, C. P. - Grison, Benjamin
Magnetosheath plasma stability and ULF wave occurrence as a function of location in the magnetosheath and upstream bow shock parameters.
Journal of Geophysical Research-Space Physics. Roč. 120, č. 4 (2015), s. 2838-2850. ISSN 2169-9380. E-ISSN 2169-9402
R&D Projects: GA ČR(CZ) GAP209/12/2394
Institutional support: RVO:68378289
Keywords : magnetosheath * mirror modes * plasma waves
Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics
Impact factor: 3.318, year: 2015
http://onlinelibrary.wiley.com/doi/10.1002/2015JA021087/full

We present the results of a statistical study of the distribution of mirror and Alfvén-ion cyclotron (AIC) waves in the magnetosheath together with plasma parameters important for the stability of ULF waves, specifically ion temperature anisotropy and ion beta. Magnetosheath crossings registered by Cluster spacecraft over the course of 2 years served as a basis for the statistics. For each observation we used bow shock, magnetopause, and magnetosheath flow models to identify the relative position of the spacecraft with respect to magnetosheath boundaries and local properties of the upstream shock crossing. A strong dependence of both plasma parameters and mirror/AIC wave occurrence on upstream ΘBn and MA is identified. We analyzed a joint dependence of the same parameters on ΘBn and fractional distance between shock and magnetopause, zenith angle, and length of the flow line. Finally, the occurrence of mirror and AIC modes was compared against the respective instability thresholds. We noted that AIC waves occurred nearly exclusively under mirror stable conditions. This is interpreted in terms of different characters of nonlinear saturation of the two modes.
Permanent Link: http://hdl.handle.net/11104/0247029