The polar cusp from a particle point of view: A statistical study based on Viking data
- Swedish Inst. of Space Physics, Kiruna (Sweden)
The authors present results from the particle measurements made on board the Viking satellite. For the period of interest the Viking orbits covered at high latitudes the whole dayside sector. Data from the Viking V-3 particle experiment acquired during the Polar Region Outer Magnetospheric International Study period have been used to study the extension of the cusp and cleft in magnetic local time and invariant latitude, and furthermore, their dependence on solar wind and interplanetary magnetic field parameters. The study is limited to the MLT range from 0900 to 1500 and to invariant latitudes (ILAT) from 74{degree} to 82{degree}. This region is divided into bins of size. The authors concentrated on the region where magnetosheath solar wind plasma penetrates more directly into the magnetosphere and is measured at Viking altitudes. This region is called the cusp proper, to be distinguished from a broader region denoted the cleft, where more energetic particles are observed. Statistically, they find the cusp proper to extend from invariant latitudes of 75{degree} to 82{degree} and magnetic local times from 0930 to 1400 MLT. The width in ILAT is found to be on average {approx}2{degree} and in MLT {approx}2 hours. It is shown that a clear correlation exists between the densities in the cusp proper calculated from the Viking V-3 experiment in the cusp proper and those in the solar wind calculated from IMP 8 measurements. It is also shown that the position of the cusp proper in MLT depends on the sense of the By component of the interplanetary magnetic field (IMF By), giving a well-defined displacement of the region of maximum occurrence toward earlier MLTs for IMF By < 0 and a less defined displacement toward later MLTs for IMF By > 0.
- OSTI ID:
- 5152790
- Journal Information:
- Journal of Geophysical Research; (United States), Vol. 96:A8; ISSN 0148-0227
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
POLAR CUSP
COORDINATES
CORRELATIONS
INTERPLANETARY MAGNETIC FIELDS
IONS
MAGNETOSHEATH
PLASMA DENSITY
SATELLITES
SOLAR WIND
STATISTICS
CHARGED PARTICLES
MAGNETIC FIELDS
MATHEMATICS
SOLAR ACTIVITY
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena