Models for plasmasphere and plasmatrough density and average ion mass including dependence on L, MLT, geomagnetic activity, and phase of the solar cycle
Using observations of mass density inferred from standing Alfvén wave frequencies and electron density inferred from plasma wave frequencies, predominantly for the Combined Release and Radiation Effects Satellite (CRRES) and Van Allen Probes spacecraft, we used symbolic nonlinear regression to find...
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Frontiers Media S.A.
2025-01-01
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| Series: | Frontiers in Astronomy and Space Sciences |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fspas.2024.1459281/full |
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| author | Richard E. Denton Kazue Takahashi David P. Hartley |
| author_facet | Richard E. Denton Kazue Takahashi David P. Hartley |
| author_sort | Richard E. Denton |
| collection | DOAJ |
| description | Using observations of mass density inferred from standing Alfvén wave frequencies and electron density inferred from plasma wave frequencies, predominantly for the Combined Release and Radiation Effects Satellite (CRRES) and Van Allen Probes spacecraft, we used symbolic nonlinear regression to find analytical formulas for the equatorial electron density, ne, mass density, ρm, and average ion mass, M≡ρm/ne. We separate the data into plasmasphere and plasmatrough populations based on the observed values of ne in order to find formulas for plasmasphere, plasmatrough, and both plasmasphere and plasmatrough. Our models depend on position, the solar extreme ultraviolet (EUV) F10.7 flux, geomagnetic activity parameters such as Kp, AE, Dst, and the solar wind dynamic pressure. Formulas for M are presented with or without ne as an input parameter. By examining formulas of varying complexity, we are able to determine the relative importance of the various dependencies. The most important dependencies for ne and ρm are that they decrease with respect to L shell and geomagnetic activity as specified by parameters such as Kp. The most important dependence of M is that M increases with respect to increasing F10.7. The value of M is close to unity within the plasmasphere, but can be significantly above 1 in the plasmatrough. Although ne and ρm have maximum value at dusk local time, M has maximum value at dawn local time. The O+ concentration is larger at dawn local time, but the O+ density can be comparable at dawn and dusk because of larger ne at dusk. |
| format | Article |
| id | doaj-art-06e1d1bc785e449a8dd8465381ca3165 |
| institution | Kabale University |
| issn | 2296-987X |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Astronomy and Space Sciences |
| spelling | doaj-art-06e1d1bc785e449a8dd8465381ca31652025-01-17T06:50:46ZengFrontiers Media S.A.Frontiers in Astronomy and Space Sciences2296-987X2025-01-011110.3389/fspas.2024.14592811459281Models for plasmasphere and plasmatrough density and average ion mass including dependence on L, MLT, geomagnetic activity, and phase of the solar cycleRichard E. Denton0Kazue Takahashi1David P. Hartley2Department of Physics and Astronomy, Dartmouth College, Hanover, NH, United StatesApplied Physics Laboratory, Johns Hopkins University, Laurel, MD, United StatesPhysics and Astronomy, University of Iowa, Iowa City, IA, United StatesUsing observations of mass density inferred from standing Alfvén wave frequencies and electron density inferred from plasma wave frequencies, predominantly for the Combined Release and Radiation Effects Satellite (CRRES) and Van Allen Probes spacecraft, we used symbolic nonlinear regression to find analytical formulas for the equatorial electron density, ne, mass density, ρm, and average ion mass, M≡ρm/ne. We separate the data into plasmasphere and plasmatrough populations based on the observed values of ne in order to find formulas for plasmasphere, plasmatrough, and both plasmasphere and plasmatrough. Our models depend on position, the solar extreme ultraviolet (EUV) F10.7 flux, geomagnetic activity parameters such as Kp, AE, Dst, and the solar wind dynamic pressure. Formulas for M are presented with or without ne as an input parameter. By examining formulas of varying complexity, we are able to determine the relative importance of the various dependencies. The most important dependencies for ne and ρm are that they decrease with respect to L shell and geomagnetic activity as specified by parameters such as Kp. The most important dependence of M is that M increases with respect to increasing F10.7. The value of M is close to unity within the plasmasphere, but can be significantly above 1 in the plasmatrough. Although ne and ρm have maximum value at dusk local time, M has maximum value at dawn local time. The O+ concentration is larger at dawn local time, but the O+ density can be comparable at dawn and dusk because of larger ne at dusk.https://www.frontiersin.org/articles/10.3389/fspas.2024.1459281/fullplasmasphereplasmatroughmass densityaverage ion massmodelsAlfvén waves |
| spellingShingle | Richard E. Denton Kazue Takahashi David P. Hartley Models for plasmasphere and plasmatrough density and average ion mass including dependence on L, MLT, geomagnetic activity, and phase of the solar cycle Frontiers in Astronomy and Space Sciences plasmasphere plasmatrough mass density average ion mass models Alfvén waves |
| title | Models for plasmasphere and plasmatrough density and average ion mass including dependence on L, MLT, geomagnetic activity, and phase of the solar cycle |
| title_full | Models for plasmasphere and plasmatrough density and average ion mass including dependence on L, MLT, geomagnetic activity, and phase of the solar cycle |
| title_fullStr | Models for plasmasphere and plasmatrough density and average ion mass including dependence on L, MLT, geomagnetic activity, and phase of the solar cycle |
| title_full_unstemmed | Models for plasmasphere and plasmatrough density and average ion mass including dependence on L, MLT, geomagnetic activity, and phase of the solar cycle |
| title_short | Models for plasmasphere and plasmatrough density and average ion mass including dependence on L, MLT, geomagnetic activity, and phase of the solar cycle |
| title_sort | models for plasmasphere and plasmatrough density and average ion mass including dependence on l mlt geomagnetic activity and phase of the solar cycle |
| topic | plasmasphere plasmatrough mass density average ion mass models Alfvén waves |
| url | https://www.frontiersin.org/articles/10.3389/fspas.2024.1459281/full |
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