Pressure Gradients Driving Ion Transport in the Topside Martian Atmosphere.
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| Title: | Pressure Gradients Driving Ion Transport in the Topside Martian Atmosphere. |
|---|---|
| Authors: | Hamil, O.1,2 oliver.hamil@eas.gatech.edu, Cravens, T. E.1, Rahmati, A.3, Connerney, J. E. P.4, Andersson, L.5 |
| Source: | Journal of Geophysical Research. Space Physics. Jul2019, Vol. 124 Issue 7, p6117-6126. 10p. |
| Subject Terms: | *Atmospheric evolution, Plasma flow, Magnetic fields, Electron density, Electron temperature, Zenith distance |
| Abstract: | Magnetic and thermal pressure gradient forces drive plasma flow in the topside ionosphere of Mars. Some of this flow can contribute to ion loss from the planet and thus affect atmospheric evolution. MAVEN measurements of the magnetic field, electron density, and electron temperature, taken over a 3‐year time period, are used to obtain averaged magnetic and thermal pressures in the topside ionosphere versus altitude, solar zenith angle, and latitude. Magnetic pressures are several times greater than thermal pressures for altitudes greater than about 300 km; that is, the plasma beta is less than one. The total pressure increases with altitude in the ionosphere and decreases with increasing solar zenith angle. Using these pressure patterns in the dayside ionosphere to estimate the pressure gradient force in the fluid momentum equation, we estimate horizontal day‐to‐night plasma flow speeds of a few kilometers per second near 400 km. Key Points: Ions are driven from the subsolar point toward the dawn/dusk terminator modeled from large‐scale MHD calculations using MAVEN dataThis study demonstrates that above about 300 km, the plasma motion should dominantly be driven by magnetic field pressureWe demonstrate quantitative agreement of magnetic pressure versus solar zenith angle over most of the dayside between MGS and MAVEN [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 |
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| Header | DbId: 8gh DbLabel: GreenFILE An: 138274428 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Pressure Gradients Driving Ion Transport in the Topside Martian Atmosphere. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Hamil%2C+O%2E%22">Hamil, O.</searchLink><relatesTo>1,2</relatesTo><i> oliver.hamil@eas.gatech.edu</i><br /><searchLink fieldCode="AR" term="%22Cravens%2C+T%2E+E%2E%22">Cravens, T. E.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Rahmati%2C+A%2E%22">Rahmati, A.</searchLink><relatesTo>3</relatesTo><br /><searchLink fieldCode="AR" term="%22Connerney%2C+J%2E+E%2E+P%2E%22">Connerney, J. E. P.</searchLink><relatesTo>4</relatesTo><br /><searchLink fieldCode="AR" term="%22Andersson%2C+L%2E%22">Andersson, L.</searchLink><relatesTo>5</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>. Jul2019, Vol. 124 Issue 7, p6117-6126. 10p. – Name: Subject Label: Subject Terms Group: Su Data: *<searchLink fieldCode="DE" term="%22Atmospheric+evolution%22">Atmospheric evolution</searchLink><br /><searchLink fieldCode="DE" term="%22Plasma+flow%22">Plasma flow</searchLink><br /><searchLink fieldCode="DE" term="%22Magnetic+fields%22">Magnetic fields</searchLink><br /><searchLink fieldCode="DE" term="%22Electron+density%22">Electron density</searchLink><br /><searchLink fieldCode="DE" term="%22Electron+temperature%22">Electron temperature</searchLink><br /><searchLink fieldCode="DE" term="%22Zenith+distance%22">Zenith distance</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Magnetic and thermal pressure gradient forces drive plasma flow in the topside ionosphere of Mars. Some of this flow can contribute to ion loss from the planet and thus affect atmospheric evolution. MAVEN measurements of the magnetic field, electron density, and electron temperature, taken over a 3‐year time period, are used to obtain averaged magnetic and thermal pressures in the topside ionosphere versus altitude, solar zenith angle, and latitude. Magnetic pressures are several times greater than thermal pressures for altitudes greater than about 300 km; that is, the plasma beta is less than one. The total pressure increases with altitude in the ionosphere and decreases with increasing solar zenith angle. Using these pressure patterns in the dayside ionosphere to estimate the pressure gradient force in the fluid momentum equation, we estimate horizontal day‐to‐night plasma flow speeds of a few kilometers per second near 400 km. Key Points: Ions are driven from the subsolar point toward the dawn/dusk terminator modeled from large‐scale MHD calculations using MAVEN dataThis study demonstrates that above about 300 km, the plasma motion should dominantly be driven by magnetic field pressureWe demonstrate quantitative agreement of magnetic pressure versus solar zenith angle over most of the dayside between MGS and MAVEN [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.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1029/2019JA026670 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 10 StartPage: 6117 Subjects: – SubjectFull: Atmospheric evolution Type: general – SubjectFull: Plasma flow Type: general – SubjectFull: Magnetic fields Type: general – SubjectFull: Electron density Type: general – SubjectFull: Electron temperature Type: general – SubjectFull: Zenith distance Type: general Titles: – TitleFull: Pressure Gradients Driving Ion Transport in the Topside Martian Atmosphere. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Hamil, O. – PersonEntity: Name: NameFull: Cravens, T. E. – PersonEntity: Name: NameFull: Rahmati, A. – PersonEntity: Name: NameFull: Connerney, J. E. P. – PersonEntity: Name: NameFull: Andersson, L. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 07 Text: Jul2019 Type: published Y: 2019 Identifiers: – Type: issn-print Value: 21699380 Numbering: – Type: volume Value: 124 – Type: issue Value: 7 Titles: – TitleFull: Journal of Geophysical Research. Space Physics Type: main |
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