The relationship betwene the strength of the storm-time ring current and the available density in the presumed source region, the plasma sheet, is examined for 23 storms with Dst (minimum Dst corrected for magnetopause currents) ranging from -50 to -164 nT. A good correlation is found between the plasma-sheet density at geosynchronous orbit and the minimum Dst. The minimum Dst is also well correlated with the eastward interplanetary electric field measured upstream by the Wind spacecraft, in agreement with previous studies, but the dependence of Dst on plasma-sheet density is unrelated to its dependence on the electric field. The best correlation is between the minimum Dst and the product of the plasma-sheet density and the eastward interplanetary electric field. These results are consistent with a scenario in which the intensity of the storm-time ring current is determined by a combination of source strength (plasma-sheet density) and injection strength (interplanetary electric field).
All Science Journal Classification (ASJC) codes
- General Earth and Planetary Sciences