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Catherine L. Johnson - One of the best experts on this subject based on the ideXlab platform.
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Improving solar wind modeling at Mercury: Incorporating transient solar phenomena into the WSA‐ENLIL model with the Cone extension
Journal of Geophysical Research: Space Physics, 2015Co-Authors: R. M. Dewey, Daniel N. Baker, Brian J. Anderson, Mehdi Benna, Catherine L. Johnson, Haje Korth, Daniel J. Gershman, William E. Mcclintock, Dusan OdstrcilAbstract:Coronal mass ejections (CMEs) and other transient solar phenomena play important roles in magnetospheric and exospheric dynamics. Although a planet may interact only occasionally with the interPlanetary consequences of these events, such transient phenomena can result in departures from the background solar wind that often involve more than an order of magnitude greater ram pressure and interPlanetary electric field applied to the Planetary Magnetosphere. For Mercury, an order of magnitude greater ram pressure combined with high Alfven speeds and reconnection rates can push the magnetopause essentially to the planet's surface, exposing the surface directly to the solar wind flow. In order to understand how the solar wind interacts with Mercury's Magnetosphere and exosphere, previous studies have used the Wang-Sheeley-Arge (WSA)-ENLIL solar wind modeling tool to calculate basic and composite solar wind parameters at Mercury's orbital location. This model forecasts only the background solar wind, however, and does not include major transient events. The Cone extension permits the inclusion of CMEs and related solar wind perturbations and thus enables characterization of the effects of strong solar wind disturbances on the Mercury system. The Cone extension is predicated on the assumption of constant angular and radial velocities of CMEs to integrate these phenomena into the WSA-ENLIL coupled model. Comparisons of the model results with observations by the MESSENGER spacecraft indicate that the WSA-ENLIL+Cone model more accurately forecasts total solar wind conditions at Mercury and has greater predictive power for magnetospheric and exospheric processes than the WSA-ENLIL model alone.
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improving solar wind modeling at mercury incorporating transient solar phenomena into the wsa enlil model with the cone extension
Journal of Geophysical Research, 2015Co-Authors: R. M. Dewey, Daniel N. Baker, Brian J. Anderson, Mehdi Benna, Catherine L. Johnson, Haje Korth, Daniel J. Gershman, William E. McclintockAbstract:Coronal mass ejections (CMEs) and other transient solar phenomena play important roles in magnetospheric and exospheric dynamics. Although a planet may interact only occasionally with the interPlanetary consequences of these events, such transient phenomena can result in departures from the background solar wind that often involve more than an order of magnitude greater ram pressure and interPlanetary electric field applied to the Planetary Magnetosphere. For Mercury, an order of magnitude greater ram pressure combined with high Alfven speeds and reconnection rates can push the magnetopause essentially to the planet's surface, exposing the surface directly to the solar wind flow. In order to understand how the solar wind interacts with Mercury's Magnetosphere and exosphere, previous studies have used the Wang-Sheeley-Arge (WSA)-ENLIL solar wind modeling tool to calculate basic and composite solar wind parameters at Mercury's orbital location. This model forecasts only the background solar wind, however, and does not include major transient events. The Cone extension permits the inclusion of CMEs and related solar wind perturbations and thus enables characterization of the effects of strong solar wind disturbances on the Mercury system. The Cone extension is predicated on the assumption of constant angular and radial velocities of CMEs to integrate these phenomena into the WSA-ENLIL coupled model. Comparisons of the model results with observations by the MESSENGER spacecraft indicate that the WSA-ENLIL+Cone model more accurately forecasts total solar wind conditions at Mercury and has greater predictive power for magnetospheric and exospheric processes than the WSA-ENLIL model alone.
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observations of mercury s northern cusp region with messenger s magnetometer
Geophysical Research Letters, 2012Co-Authors: R M Winslow, Catherine L. Johnson, Haje Korth, B J Anderson, J A Slavin, Michael E Purucker, Sean C SolomonAbstract:[1] The magnetic cusp of a Planetary Magnetosphere allows solar wind plasma to gain access to the planet's Magnetosphere and, for Mercury, the surface. From measurements by the MESSENGER Magnetometer we have characterized the magnetic field in the northern cusp region of Mercury. The first six months of orbital measurements indicate a mean latitudinal extent of the cusp of ∼11°, and a mean local time extent of 4.5 hrs, at spacecraft altitudes. From the average magnetic pressure deficit in the cusp, we estimate that (1.1 ± 0.6) × 1024 protons s−1 bombard the surface over an area of (5.2 ± 1.6) × 1011 m2near the northern cusp. Plasma pressures in the cusp are 40% higher when the interPlanetary magnetic field (IMF) is anti-sunward than when it is sunward. The influence of the IMF direction does not overcome the north-south asymmetry of Mercury's internal field, and particle flux to the surface near the southern cusp is predicted to be a factor of 4 greater than in the north. The higher particle flux impacting the surface in the south should lead to a greater exospheric source from the south and a higher rate of space weathering than in the area of the northern cusp.
A. C.-l. Chian - One of the best experts on this subject based on the ideXlab platform.
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Nonlinear Alfvén wave phenomena in the Planetary Magnetosphere
Physica Scripta, 2007Co-Authors: A. C.-l. ChianAbstract:Three nonlinear Alfven wave phenomena in the Planetary Magnetosphere are discussed: (1) magnetohydrodynamic parametric instabilities induced by a nonlinear standing Alfven wave, (2) parametric excitation of Alfven and Langmuir waves by a nonlinear electromagnetic whistler wave, and (3) parametric generation of electromagnetic waves in the vicinity of electron plasma frequency via nonlinear coupling of Langmuir and Alfven waves. Observational evidence in support of these nonlinear Alfven wave phenomena, such as the auroral Alfven-acoustic turbulence and the auroral Langmuir-Alfven-whistler (LAW) events, in the Planetary Magnetosphere is presented.
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Nonlinear Wave-Wave Interactions in Astrophysical and Space Plasmas
Astrophysics and Space Science, 1996Co-Authors: A. C.-l. ChianAbstract:We discuss nonlinear mode-mode coupling phenomena in cosmic plasmas. Four problems are considered: (1) nonlinear three-wave processes in the Planetary Magnetosphere involving the interaction of auroral Langmuir, Alfven and whistler waves, (2)nonlinear three-wave processes in the solar wind involving the modulation of Langmuir and electromagnetic waves by ion-acoustic waves, (3) order and chaos in nonlinear four-wave processes in cosmic plasmas, and (4) regular and chaotic dynamics of the relativistic Langmuir turbulence and its application to pulsar and AGN emissions. The observational evidence in support of nonlinear wave-wave interactions in space and astrophysical plasmas is presented.
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Magnetohydrodynamic parametric instabilities driven by a standing Alfven wave in the Planetary Magnetosphere
Astronomy and Astrophysics, 1994Co-Authors: A. C.-l. Chian, L. P. L. OliveiraAbstract:The parametric instabilities driven by a standing Alfven wave of circular polarization are studied. Above a certain threshold amplitude, a standing Alfven wave can generate convective or purely growing MHD parametric processes. It is shown that the threshold conditions can be satisfied by the ULF waves in the Planetary Magnetospheres. Large density fluctuations and cavities may result from the ponderomotive interaction of Alfven and acoustic waves. Application of this theory to the observation of Alfven-acoustic turbulence in the Earth's auroral plasma is discussed
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Magnetohydrodynamic parametric instabilities driven by a standing Alfven wave in the Planetary Magnetosphere
Astronomy and Astrophysics, 1994Co-Authors: A. C.-l. Chian, L. P. L. OliveiraAbstract:The parametric instabilities driven by a standing Alfven wave of circular polarization are studied. Above a certain threshold amplitude, a standing Alfven wave can generate convective or purely growing MHD parametric processes. It is shown that the threshold conditions can be satisfied by the ULF waves in the Planetary Magnetospheres. Large density fluctuations and cavities may result from the ponderomotive interaction of Alfven and acoustic waves. Application of this theory to the observation of Alfven-acoustic turbulence in the Earth's auroral plasma is discussed
L. P. L. Oliveira - One of the best experts on this subject based on the ideXlab platform.
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Magnetohydrodynamic parametric instabilities driven by a standing Alfven wave in the Planetary Magnetosphere
Astronomy and Astrophysics, 1994Co-Authors: A. C.-l. Chian, L. P. L. OliveiraAbstract:The parametric instabilities driven by a standing Alfven wave of circular polarization are studied. Above a certain threshold amplitude, a standing Alfven wave can generate convective or purely growing MHD parametric processes. It is shown that the threshold conditions can be satisfied by the ULF waves in the Planetary Magnetospheres. Large density fluctuations and cavities may result from the ponderomotive interaction of Alfven and acoustic waves. Application of this theory to the observation of Alfven-acoustic turbulence in the Earth's auroral plasma is discussed
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Magnetohydrodynamic parametric instabilities driven by a standing Alfven wave in the Planetary Magnetosphere
Astronomy and Astrophysics, 1994Co-Authors: A. C.-l. Chian, L. P. L. OliveiraAbstract:The parametric instabilities driven by a standing Alfven wave of circular polarization are studied. Above a certain threshold amplitude, a standing Alfven wave can generate convective or purely growing MHD parametric processes. It is shown that the threshold conditions can be satisfied by the ULF waves in the Planetary Magnetospheres. Large density fluctuations and cavities may result from the ponderomotive interaction of Alfven and acoustic waves. Application of this theory to the observation of Alfven-acoustic turbulence in the Earth's auroral plasma is discussed
William E. Mcclintock - One of the best experts on this subject based on the ideXlab platform.
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Improving solar wind modeling at Mercury: Incorporating transient solar phenomena into the WSA‐ENLIL model with the Cone extension
Journal of Geophysical Research: Space Physics, 2015Co-Authors: R. M. Dewey, Daniel N. Baker, Brian J. Anderson, Mehdi Benna, Catherine L. Johnson, Haje Korth, Daniel J. Gershman, William E. Mcclintock, Dusan OdstrcilAbstract:Coronal mass ejections (CMEs) and other transient solar phenomena play important roles in magnetospheric and exospheric dynamics. Although a planet may interact only occasionally with the interPlanetary consequences of these events, such transient phenomena can result in departures from the background solar wind that often involve more than an order of magnitude greater ram pressure and interPlanetary electric field applied to the Planetary Magnetosphere. For Mercury, an order of magnitude greater ram pressure combined with high Alfven speeds and reconnection rates can push the magnetopause essentially to the planet's surface, exposing the surface directly to the solar wind flow. In order to understand how the solar wind interacts with Mercury's Magnetosphere and exosphere, previous studies have used the Wang-Sheeley-Arge (WSA)-ENLIL solar wind modeling tool to calculate basic and composite solar wind parameters at Mercury's orbital location. This model forecasts only the background solar wind, however, and does not include major transient events. The Cone extension permits the inclusion of CMEs and related solar wind perturbations and thus enables characterization of the effects of strong solar wind disturbances on the Mercury system. The Cone extension is predicated on the assumption of constant angular and radial velocities of CMEs to integrate these phenomena into the WSA-ENLIL coupled model. Comparisons of the model results with observations by the MESSENGER spacecraft indicate that the WSA-ENLIL+Cone model more accurately forecasts total solar wind conditions at Mercury and has greater predictive power for magnetospheric and exospheric processes than the WSA-ENLIL model alone.
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improving solar wind modeling at mercury incorporating transient solar phenomena into the wsa enlil model with the cone extension
Journal of Geophysical Research, 2015Co-Authors: R. M. Dewey, Daniel N. Baker, Brian J. Anderson, Mehdi Benna, Catherine L. Johnson, Haje Korth, Daniel J. Gershman, William E. McclintockAbstract:Coronal mass ejections (CMEs) and other transient solar phenomena play important roles in magnetospheric and exospheric dynamics. Although a planet may interact only occasionally with the interPlanetary consequences of these events, such transient phenomena can result in departures from the background solar wind that often involve more than an order of magnitude greater ram pressure and interPlanetary electric field applied to the Planetary Magnetosphere. For Mercury, an order of magnitude greater ram pressure combined with high Alfven speeds and reconnection rates can push the magnetopause essentially to the planet's surface, exposing the surface directly to the solar wind flow. In order to understand how the solar wind interacts with Mercury's Magnetosphere and exosphere, previous studies have used the Wang-Sheeley-Arge (WSA)-ENLIL solar wind modeling tool to calculate basic and composite solar wind parameters at Mercury's orbital location. This model forecasts only the background solar wind, however, and does not include major transient events. The Cone extension permits the inclusion of CMEs and related solar wind perturbations and thus enables characterization of the effects of strong solar wind disturbances on the Mercury system. The Cone extension is predicated on the assumption of constant angular and radial velocities of CMEs to integrate these phenomena into the WSA-ENLIL coupled model. Comparisons of the model results with observations by the MESSENGER spacecraft indicate that the WSA-ENLIL+Cone model more accurately forecasts total solar wind conditions at Mercury and has greater predictive power for magnetospheric and exospheric processes than the WSA-ENLIL model alone.
E C Sittler - One of the best experts on this subject based on the ideXlab platform.
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plasma induced clearing and redistribution of material embedded in Planetary Magnetospheres
Geophysical Research Letters, 2005Co-Authors: R E Johnson, E C SittlerAbstract:[1] Charge exchange collisions between the ions trapped in a Planetary Magnetosphere and the ambient neutrals are a principal material loss process in evolving Planetary systems (Johnson, 2004). Here we show that low energy charge exchange collisions, in which orbiting occurs, can drastically modify the redistribution and loss of materials in evolving Planetary disks. Using Saturn as an example, these collisions can account for the fact that water products, produced primarily in the inner Magnetosphere, are found to be the dominant ions throughout Saturn's Magnetosphere.
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Plasma‐induced clearing and redistribution of material embedded in Planetary Magnetospheres
Geophysical Research Letters, 2005Co-Authors: R E Johnson, E C SittlerAbstract:[1] Charge exchange collisions between the ions trapped in a Planetary Magnetosphere and the ambient neutrals are a principal material loss process in evolving Planetary systems (Johnson, 2004). Here we show that low energy charge exchange collisions, in which orbiting occurs, can drastically modify the redistribution and loss of materials in evolving Planetary disks. Using Saturn as an example, these collisions can account for the fact that water products, produced primarily in the inner Magnetosphere, are found to be the dominant ions throughout Saturn's Magnetosphere.