The picture above shows the poleward (red) and equatorward (green) boundaries of the Auroral Electrojet, and thus the auroral oval, in the European sector as derived from groundbased measurements of the geomagnetic field variation. This page is updated every two minutes, the time stamp of the data used is printed in the lower right corner of the picture. The data used is one minute averages, meaning that the data is on average one minute old when presented here.
We are assuming a westward electrojet current in the dawn sector and an eastward electrojet current in the dusk sector, these are identified by the a minimum and a maximum in the magnetic field variation north-south (x) component, respectively. The poleward and equatorward boundaries are identified by the maximum and minimum in the magnetic field variation vertical (z) component (a thorough description and argumentation on this is under way).
Arrows represent the Magnetic Equivalent Convection (MEC), blue is eastward and red is westward, the arrow lengths represent the magnitude of the magnetic field variation. Assuming that the observed magnetic field variations are caused by Hall-currents, the MEC direction should be equvialent to the ionospheric F-region plasma convection.
The blue circle on the map represents the field of view at auroral altitudes (110 km) of the TGO all-sky Camera located at the Auroral Observatory in Tromsø.
The picture below shows the magnitude of the magnetic variaton (left) (maximum variation in x-component) as seen by the TGO magnetometers and the magnetic latitude of the observed maximum variation (right). In the left plot, on the y-axis 0-8 corresponds linearly to 0 to 1500 nT and 8-10 corresponds linearly to 1500 – 3000 nT.