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High latitude electric fields and the modulations related to interplanetary magnetic field parameters


  • J. P. Heppner


The meaning and characteristics of basic and average convection (i.e., electric field) patterns are described. The continuous existence of the basic convection pattern argues against treating magnetic field merging mechanisms as the fundamental cause of magnetospheric convection. However, whether related to merging or to some other mechanism, interplanetary magnetic field conditions significantly modulate the distribution, magnitudes, and boundaries of the convection pattern. A previous correlation between azimuthal, ф, angles of the inter-planetary magnetic field and asymmetries in polar cap electric field distributions as seen by OGO-6 is reviewed. A new approach is taken to reveal correlations with the north-south, θ, angle and magnitude, B, of the interplanetary field as well as additional features which correlate with the ф angle. Both significant correlations and conditions which show a lack of correlation are found. Several aspects of the correlations appear to be particularly important. One is that for a given ф angle, correlations exist relative to θ independent of B and relative to B independent of θ. A second is that shifts in the latitude of the low altitude limit of the auroral belt convection are strongly correlated with all parameters (ф, θ, B).

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