Simultaneous observations of fluctuating cusp aurora and low-latitude magnetopause reconnection

摘要

The location and variability of magnetic reconnection are investigated using simultaneous in situ observations of boundary layer flows at the dayside magnetopause and remote sensing of proton cusp aurora in the ionosphere. Two events when the Geotail spacecraft was at the magnetopause and the Imager for Magnetopause to Aurora Global Exploration (IMAGE) spacecraft was observing cusp proton precipitation are used in this investigation. The directions of high-speed flows observed in the boundary layer by the Geotail spacecraft are compared to predicted directions from the antiparallel reconnection model and from two component reconnection models. The IMAGE cusp proton aurora observations provide additional information on the type of reconnection and on variability in the reconnection rate. For the first event, antiparallel reconnection may be occurring at the magnetopause and there is a long-duration (10 s of minutes) decrease in the proton aurora intensity. For the second event, component reconnection is occurring and variability in the cusp emissions on a timescale of several minutes appears to indicate variability in the reconnection rate.