Variation of Polar Coronal Hole Profiles With Solar Cycle

摘要

We compared the H 1 Ly#alpha# polar coronal hole profiles obtained during the three Spartan 201 flights (in 1993, 1994, and 1995) and during the more recent UVCS/SOHO mission. We found that at 2.1 solar radius there are no significant variations of the line shape over the several years of the descending phase of the solar cycle. However, there may be some evidence for the 1.8 solar radius profiles being broader towards solar minimum. The profiles at 2.1 solar radius are different from profiles obtained at 1.8 solar radius; they have clearly narrower cores and wide wings. We fitted the profiles with single and/or multiple Gaussian functions and calculated their typical 1/e half widths.