Relationship between the motion of matter in coronal holes and their evolution

Abstract

We consider the evolution of a long-lived coronal hole (CH) from February to August 2002 in the zone φ = −20°…+15°, L = 30°–35°. Active structures emerged in it several times over its lifetime. After their disappearance, the CH was restored to its original form. The Carrington rotation R1989 from May 12 to May 26, 2002, is considered in detail. The relative CH areas have been determined for this rotation from observations in the HeI 1083 nm line. Based on observations in the NiI 676.8 nm line (SOHO, MDI), we have found the periods of the line-of-sight velocity variations. The variations of these periods in CHs are qualitatively compared with those of the CH areas. The oscillation periods in photospheric CH layers have been found to correlate linearly with the CH areas in the chromosphere. For the interval of observations May 12–26, 2002, we have identified 52 sites in CHs for which the area variations in the HeI 1083 nm line were estimated. For times close to the observations in the HeI 1083 nm line, we have determined the average velocities of vertical motion of matter from MDI data. The CH growth and decay have been found to be accompanied, respectively, by upward and downward motions of matter at the photospheric level.