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Table 3 Parameters for the GIC emergency alert model. The criterion for each alert level is shown in the second column, and the following columns show the expected extreme dB/dt values for RC-, AE-, and SC-type GICs

From: Extreme geomagnetically induced currents

   dB/dt of GICs
Alert level Criterion RC (nT/h) AE (nT/min) SC (nT/s)
Caution Dst < −300 nT 100–150 2000 40–110
Warning Dst < −600 nT 150–400 4000 40–110
Emergency Dst < −900 nT 400–1250 6000 40–110
Transient alert High SEP flux    40–110