Locating Flux Transfer Events in Low-Altitude Satellite Measurements (User's Guide).

摘要

Although flux transfer events (FTEs) have been observed frequently at high altitudes near the magnetopause their ionospheric signatures remain elusive. Vestiges of FTEs and other magneto-pause phenomena have possibly been detected in transient magnetic field perturbations measured on the ground at cusp latitudes. Direct observations of FTEs by instrumentation on polar orbiting satellites have not yet been forthcoming. We have developed a methodology for use by investigators based on expected, simultaneous measurements of plasma drifts (Electric fields), field-aligned currents (magnetic fields) and precipitating paricle fluxes. To test and illustrate this methodology we present the results of a search through the available S3-2 data for electric and magnetic field signatures from the mid-day sector displaying irregular structures of scales 100 to 200 km, consistent with ionospheric mapping of FTEs. Out of 36 between December 1975 and April 1976 we found five possible events. An event selected for detailed analysis was observed approximately at 2219 UT on January 1976 during an equatorward crossing of the northern dayside auroral region at about 1030 MLT. The qualitative electric and magnetic field fluctuations expected during a satellite encounter with an FTE at ionospheric altitudes are compared with single component measurement for S3-2. Keywords: Solar wind; Magnetospheres; Ionosphere coupling; Dayside cusp; Field align current; Electric fields; Flux transfer events; Reprints. (JHD)