Tangential Discontinuities: using 'Fingerprints' in the Solar Wind for Event Timing

F. C. Michel[1] ,*B. Hausman [1],Y. Kamide [1]
Solar-Terrestrial Environment Laboratory, Nagoya University[1]

Recent discussions of how changes in the interplanetary magnetic field may affect ionospheric convection or external triggering of substorms have shown that accurate prediction of when these IMF changes, detected from upstream spacecraft, reach the magnetopause is necessary. Most studies use solar wind propagation times from a spacecraft observing location; however such propagation can give large and unknown errors for magnetopause impact times. Using available high resolution solar wind data, we present a simple algorithm for identifying tangential discontinuities and obtaining accurate timing of their arrival at different locations. We also present some case studies showing that the timing precision can in principle be reduced from the 5-15 minute range of previous studies to one minute or even better.