engleski

LONG–TERM EVOLUTION OF CORONAL HOLES AND RELATED CO– ROTATING INTERACTION REGIONS

We investigate a sample of persistent coronal holes which occurred over the time range 2007 – 2014 and were observed from multiple perspectives. From combined SOHO/EIT, STEREO and SDO EUV data, we extract coronal hole parameters such as area, location, magnetic field characteristics, and follow them in time. The resulting parameters are related to in–situ solar wind measurements at L1 from ACE/Wind. We show that coronal holes undergo several evolutionary steps that are characterized by specific value ranges in the extracted parameters. On a statistical basis, this supports the results from the case study performed by Heinemann et al. (2018), who found that the coronal hole evolution has three phases, growing, maximum and decaying phase. These phases are also mirrored in the in– situ proton bulk speed of the associated high–speed streams. In addition, we investigate if and how these evolutionary properties are reflected in the galactic cosmic ray measurements of the recurrent Forbush decreases.

coronal holes, stream interaction regions

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