TEC Disturbance Index

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Updates: Every 15 minutes

See also: 30-day Disturbance Index plot.

The real-time ionospheric TEC (Total Electron Content) disturbance indices are produced at ASWFC from the real time TEC disturbance maps. The disturbance index is defined over two distinct latitude ranges (low latitudes -20 to 0; and mid latitudes -50 to -20) in the Australasian longitude sector (110 - 180E longitude).

The disturbance index in each latitude band is defined as the mean deviation of the current conditions across the latitude band from a 15-day running median reference map. It is representative of the deviation of current ionospheric conditions from those expected for the current time/day/season/solar cycle in each of the two latitude bands. The 15-day median map is used in place of a standard 30-day median to limit the effects of longer time scale ionospheric variations dominating the disturbance index. For reference the Australian regional geomagnetic activity index, Aaus is plotted in the lower panel.

The unit of the disturbance index is TECU, or 10¹⁶ electrons/m².

The data in this plot can be used to qualitatively determine whether the regional ionosphere is enhanced (positive disturbance index), depressed (negative disturbance index), or near expected monthly values (disturbance index near zero) in the Australasian region.