On the role of IMF B sub y in generating the electric field responsible for the flow across the polar cap

Journal Article · Thu Jan 01 04:00:00 EST 1987 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/JA092iA01p00195· OSTI ID:5976555

Vennerstroem, S; Friis-Christensen, E ^[1]

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1. Danish Meteorological Inst., Copenhagen (Denmark)

During periods of southward interplanetary magnetic field (IMF) the authors have examined the relationship between magnetic variations in the central polar cap and the IMF B{sub y} and B{sub z} components. The geomagnetic polar cap index PC that can be used as a measure of the flow across the polar cap has been derived using data from Thule in the IMS period. The results have been compared with IMP 8 measurements of the IMF and the solar wind velocity. The statistical analysis shows that the absolute value of the azimuthal component {vert bar}B{sub y}{vert bar} contributes to the cross-polar cap flow in the same manner as the southward component B{sub s}. The relative contributions of {vert bar}B{sub y}{vert bar} and B{sub z} have been examined and compared with the theoretical expression {upsilon}B{sub T} sin{sup 2} {theta}/2 for the merging electric field. It is found that the contribution of {vert bar}B{sub y}{vert bar} compared to B{sub z} is only half as big in the observations as in the theoretical expression. The B{sub y} effect on PC is compared to an earlier reported effect of B{sub y} on the geomagnetic index AL (Murayama et al., 1980) and found to be quite different from this. This is discussed in relation to interpretations in terms of merging site asymmetry.

• OSTI ID: 5976555
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 92:A1; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COMPARATIVE EVALUATIONS
CONVECTION
CURRENTS
DATA ANALYSIS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELECTRIC CURRENTS
ELECTRIC FIELDS
ENERGY TRANSFER
EVALUATION
GEOMAGNETIC FIELD
HEAT TRANSFER
INTERPLANETARY MAGNETIC FIELDS
IONOSPHERE
MAGNETIC FIELDS
MAGNETIC RECONNECTION
MASS TRANSFER
ORIENTATION
PLANETARY IONOSPHERES
POLAR REGIONS
SOLAR ACTIVITY
SOLAR WIND
VARIATIONS