A fresh look at the intensity and impulsive strength of geomagnetic storms

Abstract

Abstract We notice that the important early decreasing part of the main phase (MP) from the positive main phase onset (MPO) to 0-level of Dst and SymH indices is missed in the treatment of the main phase (MP) of geomagnetic storms. We correct this inconsistency in 848 storms having positive MPO (out of 1164 storms) in SymH during 1981–2019 by raising the 0-level of SymH to the MPO-level. The correction considers the full range of the main phase, increases the corrected (revised) storm intensity (SymHMin*) and impulsive strength (IpsSymH*) by up to − 149 nT and − 134 nT, respectively, and seems important for all aspects of global space weather. For example, the corrected SymHMin* changes the conventional storm identification and classification and corrected IpsSymH* clearly identifies all 3 severe space weather (SvSW) events from over 1100 normal space weather (NSW) events with a separation of 52 nT; it also identifies all 8 minor-system-damage space weather (MSW) events from the NSW events.

Keywords

• Geomagnetic storms
• Positive MPO
• Storm intensity and impulsive strength