The Solar Wind in the Outer Heliosphere

We review observations of plasma in the outer heliosphere The recent plasma data are dominated by merged interaction regions (MIRs). These MIRs differ from those observed last solar cycle in that the speed, density, magnetic field magnitude, and dynamic pressure all vary in phase. The most recent data show an increase in speed with a superposed sawtooth structure which is probably related to the equatorial extension of the solar polar coronal holes and their high‐speed solar wind. The solar wind dynamic pressure has started its solar‐cycle related increase, which should drive the termination shock outward. Comparison of the Voyager 2 plasma data with Voyager 1 energetic particle data shows a good correlation and may explain aspects of the timing of these events.