FIGURE 5.2 Radio blackout severity scales from NOAA SWPC are used by United Airlines to re-route aircraft on polar routes in response to expected radio communication blackouts. SOURCE: NOAA Space Weather Prediction Center.

In his presentation James McGovern also provided an example from October 2003 when a significant solar flare and coronal mass ejection (CME) occurred (Figure 5.5). NOAA’s SWPC issued a series of alerts, warnings, and predictions, giving power grid operators advance warning that severe space weather conditions were imminent that would put the power grid at risk. From past experience, the grid operators knew that the intensity of the DC current induced in their systems (which they monitor with their own instrumentation) scaled with the intensity of the geomagnetic storm. The intensity of the geomagnetic storm in turn is given by the K index (Table 5.1).

The power grid operators responded to warnings and to real-time space weather data provided by the NOAA SWPC (formerly the SEC, or Space Environment Center, as shown in Box 5.1) by modifying the way the power grid was operated in order to maintain adequate power quality for customers and reserve capacity to counteract the effects of space weather. Despite severe GICs, the power transmission equipment was protected and the grid maintained continuous operation. In the workshop discussion, though, McGovern pointed out that the alerts and real-time data could be improved. As an example, the K index data provided by the SWPC seemed to lag the effects on the northeastern power grid: the induced-current monitors had already reached level 2 at 01:31 on Wednesday,