Two component M-I coupling during auroral substorms

A detailed investigation of the temporal and spatial morphology of the auroral electrojets and its coupling to the magnetosphere during classical auroral substorms has been performed. This is done by superposing all available ground based magnetometers onto Polar VIS Earth Camera images. While the auroral zone ground stations are used to study the auroral electrojets the mid-latitude ground stations are used to study the net field-aligned currents coupling the auroral zone and the magnetosphere. Based on a number of case studies it is found that: 1) part of the wide intense post-midnight westward electrojet is diverted out near midnight; 2) the onset of the westward electrojet pre-midnight and post-midnight components can be shifted by several minutes relative to each other; 3) there is a significant latitudinal shift between the two westward electrojet components with the post-midnight located at a lower latitude.