Statistical analysis of mirror mode waves in sheath regions driven by interplanetary coronal mass ejection

Loading...
Thumbnail Image
Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2018-05-24
Major/Subject
Mcode
Degree programme
Language
en
Pages
16
793-808
Series
Annales Geophysicae, Volume 36, issue 3
Abstract
We present a comprehensive statistical analysis of mirror mode waves and the properties of their plasma surroundings in sheath regions driven by interplanetary coronal mass ejection (ICME). We have constructed a semi-automated method to identify mirror modes from the magnetic field data. We analyze 91 ICME sheath regions from January 1997 to April 2015 using data from the Wind spacecraft. The results imply that similarly to planetary magnetosheaths, mirror modes are also common structures in ICME sheaths. However, they occur almost exclusively as dip-like structures and in mirror stable plasma. We observe mirror modes throughout the sheath, from the bow shock to the ICME leading edge, but their amplitudes are largest closest to the shock. We also find that the shock strength (measured by Alfvén Mach number) is the most important parameter in controlling the occurrence of mirror modes. Our findings suggest that in ICME sheaths the dominant source of free energy for mirror mode generation is the shock compression. We also suggest that mirror modes that are found deeper in the sheath are remnants from earlier times of the sheath evolution, generated also in the vicinity of the shock.
Description
| openaire: EC/H2020/4100103/EU//SolMAG
Keywords
Interplanetary physics (plasma waves and turbulence; solar wind plasma), space plasma physics (waves and instabilities)
Other note
Citation
Ala-Lahti , M M , Kilpua , E K J , DImmock , A P , Osmane , A , Pulkkinen , T & Souček , J 2018 , ' Statistical analysis of mirror mode waves in sheath regions driven by interplanetary coronal mass ejection ' , Annales Geophysicae , vol. 36 , no. 3 , pp. 793-808 . https://doi.org/10.5194/angeo-36-793-2018