Aspects of magnetopause/magnetosphere response to interplanetary discontinuities, and features of magnetopause Kelvin-Helmholtz waves
We describe (i) perturbations of the magnetopause/magnetosphere elicited by an interplanetary discontinuity and (ii) the production of Kelvin-Helmholtz waves on the magnetopause. These are two large topics, so for reasons of space we combine both features in a single data example, supporting the obs...
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todo:paper_13646826_v73_n1_p40_Farrugia2023-10-03T16:11:17Z Aspects of magnetopause/magnetosphere response to interplanetary discontinuities, and features of magnetopause Kelvin-Helmholtz waves Farrugia, C.J. Gratton, F.T. Interplanetary discontinuities Kelvin-Helmholtz instability Vortex sheets Azimuthal components Current sheets Data examples Flow vectors Four cycles Helmholtz Initial perturbation Input parameter Interplanetary discontinuities Kelvin-Helmholtz instabilities Kelvin-Helmholtz waves Magnetosheaths Non-linear Northward IMF Numerical simulation Solar wind velocity Tangential stress Two stage Vortex sheet Helmholtz equation Interplanetary spacecraft Solar wind Surface waves Vortex flow Magnetosphere We describe (i) perturbations of the magnetopause/magnetosphere elicited by an interplanetary discontinuity and (ii) the production of Kelvin-Helmholtz waves on the magnetopause. These are two large topics, so for reasons of space we combine both features in a single data example, supporting the observations by theory. Correspondingly, the observations, made by ACE, consist of an interval in which a current sheet is followed by a period of strongly northward IMF. In view of recent attention directed at the effect of variations of the azimuthal component of the solar wind velocity on the magnetosphere, we chose a current sheet (CS) across which the east-west components of both field and flow vectors change polarity. A two-stage response is evident in the records of Cluster, outbound at the dusk terminator at 27° MLAT: (i) Four cycles of large-amplitude, ~3min oscillations during which the spacecraft sample alternately the cold, dense magnetosheath and the hot and tenuous magnetosphere plasmas. We argue that these motions are likely due to tangential stresses applied to the magnetopause. (ii) Soon thereafter the oscillatory character changes dramatically, and ~80s small-amplitude undulations appear which we argue to be magnetopause surface waves. Applying linear MHD theory we show these waves are due to a locally Kelvin-Helmholtz unstable boundary. As input parameters, we take values during the preceding large oscillations at the same magnetopause locale. An aspect of the non-linear phase of this instability is illustrated by a numerical simulation: the reduced duration of the evolution into large vortices by a strong initial perturbation. © 2009 Elsevier Ltd. Fil:Gratton, F.T. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_13646826_v73_n1_p40_Farrugia |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
Interplanetary discontinuities Kelvin-Helmholtz instability Vortex sheets Azimuthal components Current sheets Data examples Flow vectors Four cycles Helmholtz Initial perturbation Input parameter Interplanetary discontinuities Kelvin-Helmholtz instabilities Kelvin-Helmholtz waves Magnetosheaths Non-linear Northward IMF Numerical simulation Solar wind velocity Tangential stress Two stage Vortex sheet Helmholtz equation Interplanetary spacecraft Solar wind Surface waves Vortex flow Magnetosphere |
| spellingShingle |
Interplanetary discontinuities Kelvin-Helmholtz instability Vortex sheets Azimuthal components Current sheets Data examples Flow vectors Four cycles Helmholtz Initial perturbation Input parameter Interplanetary discontinuities Kelvin-Helmholtz instabilities Kelvin-Helmholtz waves Magnetosheaths Non-linear Northward IMF Numerical simulation Solar wind velocity Tangential stress Two stage Vortex sheet Helmholtz equation Interplanetary spacecraft Solar wind Surface waves Vortex flow Magnetosphere Farrugia, C.J. Gratton, F.T. Aspects of magnetopause/magnetosphere response to interplanetary discontinuities, and features of magnetopause Kelvin-Helmholtz waves |
| topic_facet |
Interplanetary discontinuities Kelvin-Helmholtz instability Vortex sheets Azimuthal components Current sheets Data examples Flow vectors Four cycles Helmholtz Initial perturbation Input parameter Interplanetary discontinuities Kelvin-Helmholtz instabilities Kelvin-Helmholtz waves Magnetosheaths Non-linear Northward IMF Numerical simulation Solar wind velocity Tangential stress Two stage Vortex sheet Helmholtz equation Interplanetary spacecraft Solar wind Surface waves Vortex flow Magnetosphere |
| description |
We describe (i) perturbations of the magnetopause/magnetosphere elicited by an interplanetary discontinuity and (ii) the production of Kelvin-Helmholtz waves on the magnetopause. These are two large topics, so for reasons of space we combine both features in a single data example, supporting the observations by theory. Correspondingly, the observations, made by ACE, consist of an interval in which a current sheet is followed by a period of strongly northward IMF. In view of recent attention directed at the effect of variations of the azimuthal component of the solar wind velocity on the magnetosphere, we chose a current sheet (CS) across which the east-west components of both field and flow vectors change polarity. A two-stage response is evident in the records of Cluster, outbound at the dusk terminator at 27° MLAT: (i) Four cycles of large-amplitude, ~3min oscillations during which the spacecraft sample alternately the cold, dense magnetosheath and the hot and tenuous magnetosphere plasmas. We argue that these motions are likely due to tangential stresses applied to the magnetopause. (ii) Soon thereafter the oscillatory character changes dramatically, and ~80s small-amplitude undulations appear which we argue to be magnetopause surface waves. Applying linear MHD theory we show these waves are due to a locally Kelvin-Helmholtz unstable boundary. As input parameters, we take values during the preceding large oscillations at the same magnetopause locale. An aspect of the non-linear phase of this instability is illustrated by a numerical simulation: the reduced duration of the evolution into large vortices by a strong initial perturbation. © 2009 Elsevier Ltd. |
| format |
JOUR |
| author |
Farrugia, C.J. Gratton, F.T. |
| author_facet |
Farrugia, C.J. Gratton, F.T. |
| author_sort |
Farrugia, C.J. |
| title |
Aspects of magnetopause/magnetosphere response to interplanetary discontinuities, and features of magnetopause Kelvin-Helmholtz waves |
| title_short |
Aspects of magnetopause/magnetosphere response to interplanetary discontinuities, and features of magnetopause Kelvin-Helmholtz waves |
| title_full |
Aspects of magnetopause/magnetosphere response to interplanetary discontinuities, and features of magnetopause Kelvin-Helmholtz waves |
| title_fullStr |
Aspects of magnetopause/magnetosphere response to interplanetary discontinuities, and features of magnetopause Kelvin-Helmholtz waves |
| title_full_unstemmed |
Aspects of magnetopause/magnetosphere response to interplanetary discontinuities, and features of magnetopause Kelvin-Helmholtz waves |
| title_sort |
aspects of magnetopause/magnetosphere response to interplanetary discontinuities, and features of magnetopause kelvin-helmholtz waves |
| url |
http://hdl.handle.net/20.500.12110/paper_13646826_v73_n1_p40_Farrugia |
| work_keys_str_mv |
AT farrugiacj aspectsofmagnetopausemagnetosphereresponsetointerplanetarydiscontinuitiesandfeaturesofmagnetopausekelvinhelmholtzwaves AT grattonft aspectsofmagnetopausemagnetosphereresponsetointerplanetarydiscontinuitiesandfeaturesofmagnetopausekelvinhelmholtzwaves |
| _version_ |
1807320537211338752 |