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 00:00:00 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), Vol. 92:A1; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
POLAR REGIONS
ELECTRIC FIELDS
COMPARATIVE EVALUATIONS
CONVECTION
DATA ANALYSIS
EARTH MAGNETOSPHERE
ELECTRIC CURRENTS
GEOMAGNETIC FIELD
INTERPLANETARY MAGNETIC FIELDS
IONOSPHERE
MAGNETIC RECONNECTION
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SOLAR WIND
VARIATIONS
CURRENTS
EARTH ATMOSPHERE
ENERGY TRANSFER
EVALUATION
HEAT TRANSFER
MAGNETIC FIELDS
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