A finite difference solution of the polar electrojet current mapping boundary value problem

Abstract

An investigation is made of how the polar electrojet currents and associated electric fields map down to the ground. The boundary value problem which characterizes the downward mapping of the electrojet current will be formulated using potential theory. The electrojet current is represented by a simple Cowling model in which the geomagnetic field is vertical. A numerical solution to the electrojet mapping boundary value problem is obtained via a finite difference technique. This model is employed to study the downward mapping of the polar electrojet current during intense magnetic storms occurring under sunspot maximum daytime conditions. Results of this analysis suggest that as the current maps down through the D region, from an electrojet source in the E region, it is being attenuated as well as rotated. The rotation, however, is not present at altitudes below the D region. A possible application of electrojet mapping theory to the interpretation of high-latitude ionospheric modification data taken during polar electrojet events is discussed. 2354, 1961b. Tomko, A. A., Nonlinear phenomena arising from radio wave heating of the lower ionosphere, Rep. PSU-IRL-SCI-470, 165 pp., Commun. and Space Sci. Lab., The Penn. State Univ., University Park, 1981. Van Bladel, J., Electromagnetic Fields, 556 pp., Hemisphere Publishing, New York, 1985.Volland, H., Mapping of the electric field of the Sq current into the lower atmosphere,

Orientation of the HAARP ELF ionospheric dipole and the auroral electrojet

“…Since Juneau is ∼10° E of magnetic North from HAARP, the dipole orientation is likely within 10° of magnetic EW. We assume here that the fields do not rotate as they exit the ionosphere, as described by Werner and Ferraro [1991], because the peak altitude of generation is near or below where the ambient Hall conductivity becomes dominant at higher altitudes.…”

“…In addition, the magnetometer measurements are likely dominated by the strongest electrojet altitudes (100 -120 km), which are usually above the altitudes of HF heating (70 -90 km). The currents at these altitudes may not necessarily be in the same direction [Werner and Ferraro, 1991].…”