Consideration of an ionospheric wind dynamo driven by a planetary wave with a two-day period

Abstract

The dynamo current induced by the two-day wave is examined and the resulting geomagnetic variation at ground-level is estimated. Two types of wind models are used in the calculation; they are symmetric and antisymmetric atmospheric normal modes. Results due to the antisymmetric wind model seem consistent with the observed geomagnetic variations. In this case, the center of the current vortex lies near the equator, and the total current is about 50,000 A. Induced geomagnetic variation at ground-level is about ±10 γ at 35°N, and the relationship between the southward and eastward components agrees with observation. It is also suggested that the latitude of focus of the S q current is moved with a range of ±5° by the antisymmetric two-day wave current.