Investigating the Coupled Magnetosphere-Ionosphere- Thermosphere (M-I-T) System's Responses to the 20 November 2003 Superstorm

摘要

Utilizing multi-satellite/instrument observations, we investigate the November 20 2003 Superstorm's impacts on the forward fountain, the duskside and dawnside subauroral flows, and the chemical makeup of the ionospheric plasma. New results show that the nightside forward fountain became active before local midnight and soon after the interplanetary magnetic field (IMF) turned southward at ~12 UT and remained active for the rest of 20 November and early 21 November. The fountain-related strong equatorial upward E × B drift lifted up the F2 layer above ~391 km altitude creating low plasma densities at equatorial and low latitudes. In both hemispheres, the large convection and subauroral electric (E) fields drove plasmaspheric erosions eroding the mid- and high-latitude ionosphere poleward of the plasmapause. On the duskside and dawnside, the subauroral E field drove the Subauroral Polarization Streams (SAPS) in the sunward direction. As our southern cases show, the SAPS E field changed the ionospheric plasma's chemical makeup by locally enhancing the NO~+ content and thus decreasing the O/N2 content associated with depleted plasma densities. We conclude that in the strongly coupled Magnetosphere-Ionosphere-Thermosphere system, the plasmaspheric erosion had a primary role in depleting the ionospheric plasma. Furthermore, the solar wind pressure disturbances during the longlasting southward IMF orientation led to the development of conjugate duskside and dawnside sunward SAPS flows, and SAPS flows contributed to the ionospheric plasma's depletion by increasing the NO~+ content as our southern cases show. For the first time, correlated multi-satellite observations show the dawnside sunward SAPS flows in latitudes and in longitudes.