Variability of the Sq Current: Causality and Monitoring

Historically the Sq current system has been specified on a daily basis. This assumes that the current system has no variations on shorter time-scales and that it has no regional structure. We the expansions in ground magnetometer station coverage and the processing of SuperMAG we can now test these assumptions. We present evidence that the Sq current system shows significant variability on the order of a few hours; that the Sq can double in intensity over the expected; and that the Sq can effectively vanish. We test possible causes of this observed variability. Further, we have developed a magnetic index that provides a means to monitor the intensity and variability of this current system on a 1-min cadence.