Key points are not available for this paper at this time.
The IMP‐8 and Voyager 2 spacecraft have recently detected a very strong modulation in the solar wind speed with an approximately 1.3 year period. Combined with evidence from long‐term auroral and magnetometer studies, this suggests that fundamental changes in the Sun occur on a roughly 1.3 year time scale.
Richardson et al. (Fri,) studied this question.