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James MK, Bunce EJ, Yeoman TK, Imber SM, Korth H. A statistical survey of ultralow-frequency wave power and polarization in the Hermean magnetosphere. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2016; 121:8755-8772. [PMID: 27840786 PMCID: PMC5089056 DOI: 10.1002/2016ja023103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Revised: 08/11/2016] [Accepted: 09/07/2016] [Indexed: 06/06/2023]
Abstract
We present a statistical survey of ultralow-frequency wave activity within the Hermean magnetosphere using the entire MErcury Surface, Space ENvironment, GEochemistry, and Ranging magnetometer data set. This study is focused upon wave activity with frequencies <0.5 Hz, typically below local ion gyrofrequencies, in order to determine if field line resonances similar to those observed in the terrestrial magnetosphere may be present. Wave activity is mapped to the magnetic equatorial plane of the magnetosphere and to magnetic latitude and local times on Mercury using the KT14 magnetic field model. Wave power mapped to the planetary surface indicates the average location of the polar cap boundary. Compressional wave power is dominant throughout most of the magnetosphere, while azimuthal wave power close to the dayside magnetopause provides evidence that interactions between the magnetosheath and the magnetopause such as the Kelvin-Helmholtz instability may be driving wave activity. Further evidence of this is found in the average wave polarization: left-handed polarized waves dominate the dawnside magnetosphere, while right-handed polarized waves dominate the duskside. A possible field line resonance event is also presented, where a time-of-flight calculation is used to provide an estimated local plasma mass density of ∼240 amu cm-3.
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Affiliation(s)
- Matthew K. James
- Department of Physics and AstronomyUniversity of LeicesterLeicesterUK
| | - Emma J. Bunce
- Department of Physics and AstronomyUniversity of LeicesterLeicesterUK
| | - Timothy K. Yeoman
- Department of Physics and AstronomyUniversity of LeicesterLeicesterUK
| | - Suzanne M. Imber
- Department of Physics and AstronomyUniversity of LeicesterLeicesterUK
- Department of Atmospheric, Oceanic and Space SciencesUniversity of MichiganAnn ArborMichiganUSA
| | - Haje Korth
- The Johns Hopkins University Applied Physics LaboratoryLaurelMarylandUSA
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Korth H, Tsyganenko NA, Johnson CL, Philpott LC, Anderson BJ, Al Asad MM, Solomon SC, McNutt RL. Modular model for Mercury's magnetospheric magnetic field confined within the average observed magnetopause. JOURNAL OF GEOPHYSICAL RESEARCH. SPACE PHYSICS 2015; 120:4503-4518. [PMID: 27656335 PMCID: PMC5014231 DOI: 10.1002/2015ja021022] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Revised: 04/13/2015] [Accepted: 05/07/2015] [Indexed: 06/01/2023]
Abstract
Accurate knowledge of Mercury's magnetospheric magnetic field is required to understand the sources of the planet's internal field. We present the first model of Mercury's magnetospheric magnetic field confined within a magnetopause shape derived from Magnetometer observations by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft. The field of internal origin is approximated by a dipole of magnitude 190 nT RM3, where RM is Mercury's radius, offset northward by 479 km along the spin axis. External field sources include currents flowing on the magnetopause boundary and in the cross-tail current sheet. The cross-tail current is described by a disk-shaped current near the planet and a sheet current at larger (≳ 5 RM ) antisunward distances. The tail currents are constrained by minimizing the root-mean-square (RMS) residual between the model and the magnetic field observed within the magnetosphere. The magnetopause current contributions are derived by shielding the field of each module external to the magnetopause by minimizing the RMS normal component of the magnetic field at the magnetopause. The new model yields improvements over the previously developed paraboloid model in regions that are close to the magnetopause and the nightside magnetic equatorial plane. Magnetic field residuals remain that are distributed systematically over large areas and vary monotonically with magnetic activity. Further advances in empirical descriptions of Mercury's magnetospheric external field will need to account for the dependence of the tail and magnetopause currents on magnetic activity and additional sources within the magnetosphere associated with Birkeland currents and plasma distributions near the dayside magnetopause.
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Affiliation(s)
- Haje Korth
- The Johns Hopkins University Applied Physics Laboratory Laurel Maryland USA
| | - Nikolai A Tsyganenko
- Institute and Faculty of Physics Saint Petersburg State University Saint Petersburg Russia
| | - Catherine L Johnson
- Department of Earth, Ocean and Atmospheric Sciences University of British Columbia Vancouver British Columbia Canada; Planetary Science Institute Tucson Arizona USA
| | - Lydia C Philpott
- Department of Earth, Ocean and Atmospheric Sciences University of British Columbia Vancouver British Columbia Canada
| | - Brian J Anderson
- The Johns Hopkins University Applied Physics Laboratory Laurel Maryland USA
| | - Manar M Al Asad
- Department of Earth, Ocean and Atmospheric Sciences University of British Columbia Vancouver British Columbia Canada; Saudi Aramco Dharan Saudi Arabia
| | - Sean C Solomon
- Department of Terrestrial Magnetism Carnegie Institution of Washington Washington District of Columbia USA; Lamont-Doherty Earth Observatory Columbia University Palisades New York USA
| | - Ralph L McNutt
- The Johns Hopkins University Applied Physics Laboratory Laurel Maryland USA
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Anderson BJ, Acuña MH, Korth H, Purucker ME, Johnson CL, Slavin JA, Solomon SC, McNutt RL. The Structure of Mercury's Magnetic Field from MESSENGER's First Flyby. Science 2008; 321:82-5. [DOI: 10.1126/science.1159081] [Citation(s) in RCA: 174] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Brian J. Anderson
- Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
- Solar System Exploration Division, NASA Goddard Space Fight Center, Greenbelt, MD 20771, USA
- Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
- Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA
| | - Mario H. Acuña
- Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
- Solar System Exploration Division, NASA Goddard Space Fight Center, Greenbelt, MD 20771, USA
- Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
- Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA
| | - Haje Korth
- Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
- Solar System Exploration Division, NASA Goddard Space Fight Center, Greenbelt, MD 20771, USA
- Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
- Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA
| | - Michael E. Purucker
- Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
- Solar System Exploration Division, NASA Goddard Space Fight Center, Greenbelt, MD 20771, USA
- Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
- Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA
| | - Catherine L. Johnson
- Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
- Solar System Exploration Division, NASA Goddard Space Fight Center, Greenbelt, MD 20771, USA
- Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
- Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA
| | - James A. Slavin
- Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
- Solar System Exploration Division, NASA Goddard Space Fight Center, Greenbelt, MD 20771, USA
- Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
- Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA
| | - Sean C. Solomon
- Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
- Solar System Exploration Division, NASA Goddard Space Fight Center, Greenbelt, MD 20771, USA
- Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
- Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA
| | - Ralph L. McNutt
- Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
- Solar System Exploration Division, NASA Goddard Space Fight Center, Greenbelt, MD 20771, USA
- Department of Earth and Ocean Sciences, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
- Heliophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
- Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, DC 20015, USA
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