The high‐latitude solar wind near sunspot Maximum

Abstract

We use an empirical relation between solar wind speed and coronal flux‐tube expansion to predict what Ulysses might have seen had it flown over the solar poles during 1989–1991 instead of 1994–1996. The wind speed patterns, derived from solar magnetograph data, show the following characteristics: (1) high‐speed streams having recurrence rates of 28–29 days and originating from midlatitude extensions of the polar coronal holes dominate the rising phase of the sunspot cycle (1987–1989); (2) the persistent high‐speed polar wind disappears and low‐speed wind is found at all latitudes during 1989–1990; (3) very fast, episodic “polar jets” are generated as active region fields surge to the poles at the time of polar field reversal (1990–1991). The wind speed patterns that Ulysses encounters during its second polar orbit are expected to show the same general characteristics.