IMAGE electrojet indicators IL, IU and IE

Select the date for analysis:

Year Month Day

IMAGE electrojet indicators are simple estimates of the total eastward and westward currents crossing the magnetometer network. Their definition is quite similar to that of the standard AL, AU and AE indices. For each timestep, IL(t) = min({X(t)}), where {X(t)} stands for the (geographic) north components of the magnetic field measured at the selected stations. In the same way, IU(t) = max({X(t)}), and IE = IU - IL.

Select the day using the menu above. It takes some seconds to create the plots, which will appear in another window. There you can modify the time axis, select a new set of stations, or select a new day. You can also look at the magnetograms or the contributions of individual sites to the indicators. As default, all available stations are used. The quiet time baseline is determined automatically by considering 3-hour intervals 00-03, 01-04, ..., 21-24 UT. The X range (max(X)-min(X)) at all sites is calculated for these intervals. The interval with the smallest average range is used as the baseline period.

The plots are only for quick-look purposes. For a detailed scientific analysis, we ask you to contact Ari Viljanen (ari.viljanen (at)

Comments can also be sent to Lasse Häkkinen (lasse.hakkinen (at)

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Updated: 10.2.2010