Latitudinal electron precipitation patterns during large and small IMF magnitudes for northward IMF conditions

Abstract

We demonstrate that there are distinct differences in the electron precipitation patterns (or the polar cap size), geomagnetic activity, and field‐aligned currents in the highest‐latitude region for small and large IMF Bz values when the IMF Bz component is positive. First, during periods of weakly northward IMF, there is a distinct area in the highest‐latitude region in which the electron precipitation is absent except for the polar rain. By contrast, during strongly northward IMF, the entire polar region is often filled with burst‐type soft electron precipitations. Second, geomagnetic disturbances and field‐aligned‐current intensitites in the highest‐latitude region (>80° in geomagnetic latitude) are less during a weak IMF Bz condition than those during a strongly northward IMF Bz condition. Geomagnetic activity in the auroral zone for both conditions is absent or very weak.