Statistical study of the proton isotropy boundary
Based on a large data set of polar NOAA-type satellite observations we studied the latitude-MLT shape of the 80keV proton isotropy boundary (IB) as a function of the solar wind parameters and magnetic activity. Using "snapshots" of isotropy boundaries near-simultaneously crossed at fou...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2005-06-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/23/1311/2005/angeo-23-1311-2005.pdf |
| Summary: | Based on a large data set of polar NOAA-type satellite observations
we studied the latitude-MLT shape of the 80keV proton isotropy
boundary (IB) as a function of the solar wind parameters and
magnetic activity. Using "snapshots" of isotropy boundaries
near-simultaneously crossed at four points we found that its
equatorward expansion, as well as its dawn-dusk shift, depends
mostly on the <i>AE</i>-index and on the corrected <i>D<sub>st</sub></i>*, whereas the
amplitude of the IB daily variation is mostly controlled by the
solar wind dynamic pressure. Applying a nonlinear, multi-parametric,
least-square regression procedure, the empirical relationship
describing the IB latitude as a function of MLT and <i>AE</i>, Pd, <i>D<sub>st</sub></i>* parameters was obtained. Comparing it with the predictions from the
Tsyganenko-2001 model we found a good agreement during the quiet
time but some important differences during the disturbed periods.
Interpretation of these results in terms of the properties of the
magnetospheric configuration is briefly discussed. |
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| ISSN: | 0992-7689 1432-0576 |