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The high‐latitude solar wind near sunspot Maximum
Author(s) -
Wang Y.M.,
Sheeley N. R.
Publication year - 1997
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/97gl53305
Subject(s) - coronal hole , polar , sunspot , physics , solar wind , wind speed , solar minimum , latitude , solar maximum , coronal mass ejection , flux (metallurgy) , solar cycle 22 , atmospheric sciences , middle latitudes , solar cycle , polar wind , meteorology , astronomy , magnetic field , materials science , quantum mechanics , metallurgy
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.