Interplay of solar wind parameters and physical mechanisms producing the saturation of the cross polar cap potential
Abstract The nonlinear response of the cross polar cap potential (CPCP) to solar wind driving electric field is a well‐known phenomenon. The reasons behind this saturation, however, are still under debate. We have performed a statistical study of the coupling efficiency between the solar wind and th...
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| Format: | Article |
| Language: | English |
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Wiley
2017-04-01
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| Series: | Geophysical Research Letters |
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| Online Access: | https://doi.org/10.1002/2017GL072676 |
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| author | M. Myllys E. K. J. Kipua B. Lavraud |
| author_facet | M. Myllys E. K. J. Kipua B. Lavraud |
| author_sort | M. Myllys |
| collection | DOAJ |
| description | Abstract The nonlinear response of the cross polar cap potential (CPCP) to solar wind driving electric field is a well‐known phenomenon. The reasons behind this saturation, however, are still under debate. We have performed a statistical study of the coupling efficiency between the solar wind and the northern polar cap index (PCN). PCN is used as a proxy for the CPCP. Our main focus is in quantifying how the solar wind dynamic pressure alters the efficiency. We show that the saturation of PCN occurs both during low and moderate upstream MA conditions. We also show that the increasing dynamic pressure is associated with increasing PCN. In addition, we find that the coupling is different depending on which parameter, the velocity or the magnetic field, increases the solar wind driving electric field: the higher the velocity the higher the coupling efficiency. |
| format | Article |
| id | doaj-art-5f9834bd0ea54d65bb6960c1afd7d9ed |
| institution | OA Journals |
| issn | 0094-8276 1944-8007 |
| language | English |
| publishDate | 2017-04-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geophysical Research Letters |
| spelling | doaj-art-5f9834bd0ea54d65bb6960c1afd7d9ed2025-08-20T02:31:41ZengWileyGeophysical Research Letters0094-82761944-80072017-04-014473019302710.1002/2017GL072676Interplay of solar wind parameters and physical mechanisms producing the saturation of the cross polar cap potentialM. Myllys0E. K. J. Kipua1B. Lavraud2Department of Physics University of Helsinki Helsinki FinlandDepartment of Physics University of Helsinki Helsinki FinlandInstitut de Recherche en Astrophysique et Planétologie Toulouse FranceAbstract The nonlinear response of the cross polar cap potential (CPCP) to solar wind driving electric field is a well‐known phenomenon. The reasons behind this saturation, however, are still under debate. We have performed a statistical study of the coupling efficiency between the solar wind and the northern polar cap index (PCN). PCN is used as a proxy for the CPCP. Our main focus is in quantifying how the solar wind dynamic pressure alters the efficiency. We show that the saturation of PCN occurs both during low and moderate upstream MA conditions. We also show that the increasing dynamic pressure is associated with increasing PCN. In addition, we find that the coupling is different depending on which parameter, the velocity or the magnetic field, increases the solar wind driving electric field: the higher the velocity the higher the coupling efficiency.https://doi.org/10.1002/2017GL072676polar cap saturationpolar cap indexcoupling efficiency |
| spellingShingle | M. Myllys E. K. J. Kipua B. Lavraud Interplay of solar wind parameters and physical mechanisms producing the saturation of the cross polar cap potential Geophysical Research Letters polar cap saturation polar cap index coupling efficiency |
| title | Interplay of solar wind parameters and physical mechanisms producing the saturation of the cross polar cap potential |
| title_full | Interplay of solar wind parameters and physical mechanisms producing the saturation of the cross polar cap potential |
| title_fullStr | Interplay of solar wind parameters and physical mechanisms producing the saturation of the cross polar cap potential |
| title_full_unstemmed | Interplay of solar wind parameters and physical mechanisms producing the saturation of the cross polar cap potential |
| title_short | Interplay of solar wind parameters and physical mechanisms producing the saturation of the cross polar cap potential |
| title_sort | interplay of solar wind parameters and physical mechanisms producing the saturation of the cross polar cap potential |
| topic | polar cap saturation polar cap index coupling efficiency |
| url | https://doi.org/10.1002/2017GL072676 |
| work_keys_str_mv | AT mmyllys interplayofsolarwindparametersandphysicalmechanismsproducingthesaturationofthecrosspolarcappotential AT ekjkipua interplayofsolarwindparametersandphysicalmechanismsproducingthesaturationofthecrosspolarcappotential AT blavraud interplayofsolarwindparametersandphysicalmechanismsproducingthesaturationofthecrosspolarcappotential |