Comparison of the modeled region of open field lines with the observed poleward boundary of auroral electron precipitation
Abstract
The geometry of the open field line regions in the earth's magnetosphere is calculated by utilizing the Olson-Pfitzer (1974) geomagnetic field model upon which a uniform interplanetary magnetic vector field is superimposed. Results of these calculations are compared to observations of the poleward boundary of the auroral electron precipitation region on a case-by-case basis as made by the DMSP-F2 satellite. This boundary is considered to be a very good indicator of the transition from open to closed field lines. The satellite data used were taken during geomagnetically quiet intervals; for this set, the median predicted latitude is found to be 1.7 deg equatorward of the median observed latitude. Further grouping of the results shows a local time dependence such that, in early afternoon (magnetic local time), the average modelled latitudes are generally poleward of the observed latitudes, which is in contrast to the overall dependence. No definite dependences of the modelled to observed boundaries on the IMF magnitude, its components, the value of the AE index, or the value of the Kp are found. Separation of the data by hemisphere shows that there is a better correspondence between the modelled and observed boundaries for the southern polar cap, especially for the afternoon sector.
- Publication:
-
Annales Geophysicae
- Pub Date:
- June 1988
- Bibcode:
- 1988AnGeo...6..265B
- Keywords:
-
- Auroral Zones;
- Electron Precipitation;
- Magnetic Field Configurations;
- Magnetospheric Electron Density;
- Dmsp Satellites;
- Geomagnetism;
- Interplanetary Magnetic Fields;
- Magnetohydrodynamics;
- Polar Caps