The earth's quasi-parallel bow-shock: review of observations and perspectives for Cluster

Research output: Contribution to journalArticle

Abstract

Spacecraft crossings of the Earth's quasi-parallel bow shock under typical high Mach number conditions are characterized by the presence of large-amplitude, compressive, low-frequency magnetic pulsations. Thus, instead of the fairly abrupt jump from upstream to downstream states one associates with their quasi-perpendicular counterparts, quasi-parallel shocks are more aptly described in terms of an extended transition from upstream to downstream conditions. The complex, turbulent appearance of the quasi-parallel shock diverted much of the research efforts in the field towards the quasi-perpendicular regime until about 15 years ago. This paper reviews what we have learnt about the quasi-parallel shock transition zone from spacecraft observations at the Earth's bow shock in the last decade and a half. Field and particle measurements suggest a prominent role is played by short (not, vert, similar10 s) large-amplitude (|δB|/|B|>2, typically 3 or more) magnetic structures that evolve out of the upstream wave field and are convected towards the shock by the supersonic solar wind. As these structures grow in amplitude, they steepen, slow down in the shock rest frame and begin to merge with similar structures, leading to the downstream state. A number of questions about the nature of the quasi-parallel shock transition remain and the possible contribution Cluster may make towards their resolution is highlighted.
Original languageEnglish
Pages (from-to)629-647
Number of pages19
JournalPlanetary and Space Science
Volume51
Issue number11
Publication statusPublished - Sep 2003

Fingerprint

bows
shock
upstream
spacecraft
Mach number
solar wind
low frequencies

Keywords

  • Quasi-parallel shocks
  • Solar-wind
  • Earth's bow shock
  • Waves
  • Ions
  • Collisionless shocks

Cite this

@article{7f80a8dc97e84f2c87aeeb5d2d9809f9,
title = "The earth's quasi-parallel bow-shock: review of observations and perspectives for Cluster",
abstract = "Spacecraft crossings of the Earth's quasi-parallel bow shock under typical high Mach number conditions are characterized by the presence of large-amplitude, compressive, low-frequency magnetic pulsations. Thus, instead of the fairly abrupt jump from upstream to downstream states one associates with their quasi-perpendicular counterparts, quasi-parallel shocks are more aptly described in terms of an extended transition from upstream to downstream conditions. The complex, turbulent appearance of the quasi-parallel shock diverted much of the research efforts in the field towards the quasi-perpendicular regime until about 15 years ago. This paper reviews what we have learnt about the quasi-parallel shock transition zone from spacecraft observations at the Earth's bow shock in the last decade and a half. Field and particle measurements suggest a prominent role is played by short (not, vert, similar10 s) large-amplitude (|δB|/|B|>2, typically 3 or more) magnetic structures that evolve out of the upstream wave field and are convected towards the shock by the supersonic solar wind. As these structures grow in amplitude, they steepen, slow down in the shock rest frame and begin to merge with similar structures, leading to the downstream state. A number of questions about the nature of the quasi-parallel shock transition remain and the possible contribution Cluster may make towards their resolution is highlighted.",
keywords = "Quasi-parallel shocks, Solar-wind, Earth's bow shock, Waves, Ions, Collisionless shocks",
author = "William Wilkinson",
year = "2003",
month = "9",
language = "English",
volume = "51",
pages = "629--647",
journal = "Planetary and Space Science",
issn = "0032-0633",
number = "11",

}

The earth's quasi-parallel bow-shock: review of observations and perspectives for Cluster. / Wilkinson, William.

In: Planetary and Space Science, Vol. 51, No. 11, 09.2003, p. 629-647.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The earth's quasi-parallel bow-shock: review of observations and perspectives for Cluster

AU - Wilkinson, William

PY - 2003/9

Y1 - 2003/9

N2 - Spacecraft crossings of the Earth's quasi-parallel bow shock under typical high Mach number conditions are characterized by the presence of large-amplitude, compressive, low-frequency magnetic pulsations. Thus, instead of the fairly abrupt jump from upstream to downstream states one associates with their quasi-perpendicular counterparts, quasi-parallel shocks are more aptly described in terms of an extended transition from upstream to downstream conditions. The complex, turbulent appearance of the quasi-parallel shock diverted much of the research efforts in the field towards the quasi-perpendicular regime until about 15 years ago. This paper reviews what we have learnt about the quasi-parallel shock transition zone from spacecraft observations at the Earth's bow shock in the last decade and a half. Field and particle measurements suggest a prominent role is played by short (not, vert, similar10 s) large-amplitude (|δB|/|B|>2, typically 3 or more) magnetic structures that evolve out of the upstream wave field and are convected towards the shock by the supersonic solar wind. As these structures grow in amplitude, they steepen, slow down in the shock rest frame and begin to merge with similar structures, leading to the downstream state. A number of questions about the nature of the quasi-parallel shock transition remain and the possible contribution Cluster may make towards their resolution is highlighted.

AB - Spacecraft crossings of the Earth's quasi-parallel bow shock under typical high Mach number conditions are characterized by the presence of large-amplitude, compressive, low-frequency magnetic pulsations. Thus, instead of the fairly abrupt jump from upstream to downstream states one associates with their quasi-perpendicular counterparts, quasi-parallel shocks are more aptly described in terms of an extended transition from upstream to downstream conditions. The complex, turbulent appearance of the quasi-parallel shock diverted much of the research efforts in the field towards the quasi-perpendicular regime until about 15 years ago. This paper reviews what we have learnt about the quasi-parallel shock transition zone from spacecraft observations at the Earth's bow shock in the last decade and a half. Field and particle measurements suggest a prominent role is played by short (not, vert, similar10 s) large-amplitude (|δB|/|B|>2, typically 3 or more) magnetic structures that evolve out of the upstream wave field and are convected towards the shock by the supersonic solar wind. As these structures grow in amplitude, they steepen, slow down in the shock rest frame and begin to merge with similar structures, leading to the downstream state. A number of questions about the nature of the quasi-parallel shock transition remain and the possible contribution Cluster may make towards their resolution is highlighted.

KW - Quasi-parallel shocks

KW - Solar-wind

KW - Earth's bow shock

KW - Waves

KW - Ions

KW - Collisionless shocks

M3 - Article

VL - 51

SP - 629

EP - 647

JO - Planetary and Space Science

JF - Planetary and Space Science

SN - 0032-0633

IS - 11

ER -