Ionospheric signatures of magnetopause pocesses

Whilst it is well-accepted that short-duration changes to the Interplanetary Magnetic Field (IMF) and solar wind cause high-latitude ionospheric transients observed by magnetic, optical and radar techniques, a coherent explanation of the zoo of signatures remains illusive. The paper describes some of the problems involved in the interpretation of dayside transient features, all of which result from time-and spatially-varying field-aligned currents. A brief discussion of how internal magnetospheric processes can directly affect the rate at which energy is transferred across the magnetopause is discussed. Further progress will require carefully-coordinated measurements from ground-based networks of observatories with complementary measurements from space.