Dst index for May 2005
Provisional Dst index for the whole month of May 2005. The Disturbance Storm Time index or Dst index indicates the severity of geomagnetic storms. The more negative the index, the more intense is the storm.
By definition, a magnetic storm occurs when the Dst index exceeds -100 nT. As one can see on this plot, 2 moderate (~ -100 nT) magnetic storms occurred, one on 8 May and one on 30 May. A more abrupt and intense storm happened on 15 May with a DsT index of ~ -250 nT in a couple of hours.