Statistical Study of Foreshock Bubbles, Hot Flow Anomalies, and Spontaneous Hot Flow Anomalies and Their Substructures Observed by MMS.
Saved in:
| Title: | Statistical Study of Foreshock Bubbles, Hot Flow Anomalies, and Spontaneous Hot Flow Anomalies and Their Substructures Observed by MMS. |
|---|---|
| Authors: | Vu, Andrew1, Liu, Terry Z.1,2,3, Zhang, Hui1 hzhang14@alaska.edu, Pollock, Craig4 |
| Source: | Journal of Geophysical Research. Space Physics. Feb2022, Vol. 127 Issue 2, p1-21. 21p. |
| Subject Terms: | Gravity anomalies, Magnetic flux density, Solar wind, Wind speed, Bow shock (Astrophysics) |
| Abstract: | Foreshock transients such as foreshock bubbles (FBs), hot flow anomalies (HFAs), and spontaneous hot flow anomalies (SHFAs) display heated, tenuous cores and large flow deflections bounded by compressional boundaries. THEMIS and Cluster observations show that some cores contain local density enhancements which can be studied to better understand the evolution processes of foreshock transients. However, closer examinations of these substructures were not feasible until the availability of the higher resolution data from the Magnetospheric Multiscale mission (MMS). We identify 164 FB‐like, HFA‐like, and SHFA events from two MMS dayside phases for a statistical study to investigate their solar wind conditions, properties, and substructure properties. Occurrence rates of the three event types are higher for lower magnetic field strengths, higher solar wind speeds and Mach numbers, and quasi‐parallel bow shocks. Events usually span up to 3 RE along the bow shock surface and extend up to 6 RE upstream from the bow shock. Though events with and without substructures exhibit similar solar wind conditions, events with substructures are more likely to have longer core durations and larger sizes. Substructure densities display a positive correlation with bulk flows and a negative correlation with temperatures. Substructure sizes vary between 4 and 24 ion inertial lengths, indicating multiple formation mechanisms. Substructures could be the boundary between two foreshock transient events that have merged into a single event, fast‐mode variations, generated by slow or mirror mode instabilities, or produced from instabilities due to parameter gradients at the compressional boundaries or shocks. Key Points: Foreshock transient events with and without substructures have the same solar wind conditions as those from prior statistical studiesSubstructures could be compressional boundaries between two merged events, fast‐mode variations, or due to slow/mirror mode instabilitiesEvents with substructures have longer core durations and larger sizes and would cause more complicated geoeffects than those without [ABSTRACT FROM AUTHOR] |
| Copyright of Journal of Geophysical Research. Space Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | GreenFILE |
| FullText | Text: Availability: 0 |
|---|---|
| Header | DbId: 8gh DbLabel: GreenFILE An: 155485408 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
| IllustrationInfo | |
| Items | – Name: Title Label: Title Group: Ti Data: Statistical Study of Foreshock Bubbles, Hot Flow Anomalies, and Spontaneous Hot Flow Anomalies and Their Substructures Observed by MMS. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Vu%2C+Andrew%22">Vu, Andrew</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Liu%2C+Terry+Z%2E%22">Liu, Terry Z.</searchLink><relatesTo>1,2,3</relatesTo><br /><searchLink fieldCode="AR" term="%22Zhang%2C+Hui%22">Zhang, Hui</searchLink><relatesTo>1</relatesTo><i> hzhang14@alaska.edu</i><br /><searchLink fieldCode="AR" term="%22Pollock%2C+Craig%22">Pollock, Craig</searchLink><relatesTo>4</relatesTo> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Journal+of+Geophysical+Research%2E+Space+Physics%22">Journal of Geophysical Research. Space Physics</searchLink>. Feb2022, Vol. 127 Issue 2, p1-21. 21p. – Name: Subject Label: Subject Terms Group: Su Data: <searchLink fieldCode="DE" term="%22Gravity+anomalies%22">Gravity anomalies</searchLink><br /><searchLink fieldCode="DE" term="%22Magnetic+flux+density%22">Magnetic flux density</searchLink><br /><searchLink fieldCode="DE" term="%22Solar+wind%22">Solar wind</searchLink><br /><searchLink fieldCode="DE" term="%22Wind+speed%22">Wind speed</searchLink><br /><searchLink fieldCode="DE" term="%22Bow+shock+%28Astrophysics%29%22">Bow shock (Astrophysics)</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Foreshock transients such as foreshock bubbles (FBs), hot flow anomalies (HFAs), and spontaneous hot flow anomalies (SHFAs) display heated, tenuous cores and large flow deflections bounded by compressional boundaries. THEMIS and Cluster observations show that some cores contain local density enhancements which can be studied to better understand the evolution processes of foreshock transients. However, closer examinations of these substructures were not feasible until the availability of the higher resolution data from the Magnetospheric Multiscale mission (MMS). We identify 164 FB‐like, HFA‐like, and SHFA events from two MMS dayside phases for a statistical study to investigate their solar wind conditions, properties, and substructure properties. Occurrence rates of the three event types are higher for lower magnetic field strengths, higher solar wind speeds and Mach numbers, and quasi‐parallel bow shocks. Events usually span up to 3 RE along the bow shock surface and extend up to 6 RE upstream from the bow shock. Though events with and without substructures exhibit similar solar wind conditions, events with substructures are more likely to have longer core durations and larger sizes. Substructure densities display a positive correlation with bulk flows and a negative correlation with temperatures. Substructure sizes vary between 4 and 24 ion inertial lengths, indicating multiple formation mechanisms. Substructures could be the boundary between two foreshock transient events that have merged into a single event, fast‐mode variations, generated by slow or mirror mode instabilities, or produced from instabilities due to parameter gradients at the compressional boundaries or shocks. Key Points: Foreshock transient events with and without substructures have the same solar wind conditions as those from prior statistical studiesSubstructures could be compressional boundaries between two merged events, fast‐mode variations, or due to slow/mirror mode instabilitiesEvents with substructures have longer core durations and larger sizes and would cause more complicated geoeffects than those without [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Journal of Geophysical Research. Space Physics is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
| PLink | https://search.ebscohost.com/login.aspx?direct=true&site=eds-live&db=8gh&AN=155485408 |
| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1029/2021JA030029 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 21 StartPage: 1 Subjects: – SubjectFull: Gravity anomalies Type: general – SubjectFull: Magnetic flux density Type: general – SubjectFull: Solar wind Type: general – SubjectFull: Wind speed Type: general – SubjectFull: Bow shock (Astrophysics) Type: general Titles: – TitleFull: Statistical Study of Foreshock Bubbles, Hot Flow Anomalies, and Spontaneous Hot Flow Anomalies and Their Substructures Observed by MMS. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Vu, Andrew – PersonEntity: Name: NameFull: Liu, Terry Z. – PersonEntity: Name: NameFull: Zhang, Hui – PersonEntity: Name: NameFull: Pollock, Craig IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 02 Text: Feb2022 Type: published Y: 2022 Identifiers: – Type: issn-print Value: 21699380 Numbering: – Type: volume Value: 127 – Type: issue Value: 2 Titles: – TitleFull: Journal of Geophysical Research. Space Physics Type: main |
| ResultId | 1 |
