Substorms, Plasmoids, Flux Robes, and Magnetotail Flux Loss on March 25, 1983: CDAW-8

摘要

During a 9-hour period following a storm-sudden commencement, six space-craft near geosynchronous orbit, one over the pole, and three in the magnetotail, monitored a complex sequence of magnetospheric variations. Magnetic field compressions associated with the sudden commencement were seen first by the near earth spacecraft and subsequently by the three down-tail spacecraft with increasing time delays that were consistent with the tailward movement of an interplanetary-shock-associated pressure enhancement. Ground magnetograms and synchronous orbit data are used to identify 7 substorm intensifications during this geomagnetically active period. Six of these intensifications are clearly associated with tail lobe field decreases about 18 R sub E behind the earth. Four of these intensifications are followed by both Bz field increases in the tail lobes at about 18 and about 30 R sub E and by the subsequent observation of rapidly flowing plasma sheet plasma at ISEE 3 about 110 R sub E down the tail. During two substorms where DE 1 was optically observing the auroral oval, the area of the polar cap was observed to decrease as the tail lobe field decreased at 18 R sub E. All these observations are consistent with the substorm associated release of a plasmoid at a neutral line near 20 R sub E; however, the classical north-south variation of the plasma sheet magnetic field, thought to be characteristic of the passage of a plasmoid in the deep tail, was not seen in every case. Keywords: Geosynchronous orbit; Solar wind; Magnetospheric variations; Plasma sheet.