Remote sensing of flux transfer events: Investigation of theoretical constraints based on model magnetopause time series data

摘要

A method for inferring the cross-sectional shape, size, and speed of propagation of magnetopause flux transfer events (FTEs) has previously been described in the literature. This method is based on two-dimensional, steady state MHD, which in principle requires that the perturbing obstacle generating the FTE signatures be quasi-two-dimensional and quasi-steady for the duration of its encounter with the sensing satellite. Since such conditions are unlikely to be met at the magnetopause, we investigate the applicability of the remote-sensing method to spacecraft data by systematically applying it to a series of data sets containing FTE-like signatures generated by two- and three-dimensional (2-D and 3D), time-dependent models of Petschek-type reconnection. In this model the propagation of the outflow region away from the reconnection site gives rise to FTE-like signatures in the ambient plasma. The outflow region varies in both space and time, thus providing a test; of the remote-sensing method to deal with such situations; The results of our analysis show that the method is robust to both time variations (particularly with respect to the rate of growth and speed of propagation of the obstacle) and space variations, provided the perturbations generated by the model can be identified as coherent FTE signatures. Thus on the basis of our comparison with results of 2-D and 3-D, time-dependent models we conclude that the remote sensing method is more generally applicable to magnetopause data sets than might at first be expected on the basis of the theoretical constraints alone. [References: 17]