A model of the magnetospheric substorm
IT is generally recognised that the Earth's magnetic tail and the plasma sheet play a vital role in the processes responsible for the observational phenomenon known as the magnetospheric substorm. Many different models1–5 of substorm behaviour have been described with differing degrees of success, and to propose another requires some justification. A new model, if it is to be useful, must do two things. It must be specific enough to make quantitative theoretical analysis possible, and it must fit the morphological features more completely or in a more elegant way than other models. In addition, it should be distinctive enough from other models to be separated from them by observational tests. I believe the model presented here has those properties.
CHANGES IN MAGNETOSPHERIC CONFIGURATION DURING SUBSTORM GROWTH PHASE.
Abstract : Four simple calculations suggest that the magnetosphere changes its configuration during substorm growth phase. A flaring tail model indicates that the observed increases in geomagnetic tail field can only be explained if the dayside magnetopause shrinks by 1-2 RE. The same assumption is needed to explain large magentic decreases observed at geostationary orbit. A plasma sheet model, consistent with a flaring tail, indicates that increased tail falring leads to plasma sheet thinning, and a decrease in northward magentic field, during substorm growth phase. The motion of the inner edge of the plasma sheet, and consequently an equatorward shift of the nightside auroral oval, is consistent with the above structural modifications. (Author)
Field‐aligned currents in the magnetosphere
Certain satellite and terrestrial observations of transient magnetic fluctuations show a high degree of localization, while other observations are of a definite worldwide character. The worldwide fluctuations in the magnetic field are probably well explained in terms of hydromagnetic waves propagating through the magnetosphere in modes with the wave polarization current flowing perpendicular to the geomagnetic field. However, for the localized fluctuations such an interpretation is inconsistent with present theory of hydromagnetic wave propagation in the magnetosphere. We suggest that the observations of localized magnetic fluctuations might be better interpreted in terms of field-aligned currents in the magnetosphere.