Magnetospheric Response to Solar Wind Variations

摘要

The time lagged response of the magnetosphere to solar wind variations has been determined using the linear prediction filtering method and 34 intervals of high time resolution IMP-8 solar wind data and auroral electrojet AL index data. The linear prediction filtering method is a powerful time series analysis technique which is utilized to produce a filter of time lagged response coefficients which estimates the most general linear relationship between magnetospheric activity and solar wind variations. This study uses the AL index to monitor the magnetosphere's response and VB/sub s/ to monitor the solar wind input. Before analysis, the median value of the AL index for each of the 34 intervals was utilized to rank the intervals according to the level of geomagnetic activity. It is found that the VB/sub s/-AL filters are composed of two response pulses peaking at time lags of 20-minutes and 60-minutes. Our interpretation associates the 20-minute pulse with activity driven directly by solar wind-magnetosphere interaction and it associates the 60-minute pulse with activity driven by the release of stored energy from the magnetotail. Thus, the filter results suggest that both the directly driven and the unloading models of magnetospheric response are important in describing the time lagged response of the magnetosphere to solar wind variations. 11 refs., 3 figs. (ERA citation 10:028995)