A new technique for understanding magnetosphere–ionosphere coupling using directional derivatives of SuperDARN convection flow
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The purpose of this paper is to present and evaluate a new technique to better understand ionospheric convection and it’s magnetospheric drivers using convection maps derived from the Super Dual Auroral Radar Network (SuperDARN). We postulate that the directional derivative of the SuperDARN ionospheric convection flow can be used as a technique for understanding solar wind–magnetosphere–ionosphere coupling by identifying regions of strong acceleration/deceleration of plasma flow associated with drivers of magnetospheric convection such as magnetic reconnection. Thus, the technique may be used to identify the open–closed magnetic field line boundary (OCB) in certain circumstances. In this study, directional derivatives of the SuperDARN ionospheric convection flow over a four and a half hour interval on Nov. 04, 2001, is presented during which the interplanetary magnetic field was predominantly southward. At each one-minute time point in the interval the positive peak in the directional derivative of flow is identified and evaluated via comparison with known indicators of the OCB including the poleward boundary of ultraviolet emissions from three FUV detectors onboard the IMAGE spacecraft as well as the SuperDARN spectral widths. Good comparison is found between the location of the peak in the directional derivative of SuperDARN flow and the poleward boundary of ultraviolet emissions confirming that acceleration of ionospheric plasma flow is associated with magnetic reconnection and the open–closed boundary.
KeywordsSuperDARN directional derivative technique ionospheric convection driven by solar wind–magnetosphere–ionosphere coupling open–closed magnetic field line boundary
This work was supported by the Natural Sciences and Engineering Research Council of Canada. The authors thank the SuperDARN PIs for providing the SuperDARN data and software. We gratefully acknowledge the IMAGE FUV Imager team and PI Stephen Mende. Auroral boundary data were derived and provided by the British Antarctic Survey based on IMAGE satellite data. The SuperDARN data were collected from superdarn.org. The OMNI data were obtained from the GSFC/SPDF OMNIWeb interface.
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