engleski

CORONAL HOLE AND ACTIVE REGION INTERACTION OBSERVED THROUGH A CME-HSS INTERACTION

Understanding the evolution of coronal holes (CH) is a key towards a better understanding of solar wind high-speed streams and consequently their Space Weather effects. The goal is to examine in a thorough study, using stereoscopic remote sensing observations as well as in-situ data and modeling efforts, the evolution of a CME launched from an active region which is spatially close to a coronal hole. Due to the different regimes of open and closed field lines, the CME deviates significantly from a radial propagation direction. From this active region a C7.7 flare event occurred on June 21, 2011 together with an associated CME that was Earth-directed. Using SDO data and magnetic field modeling we examine the surface properties of this event. A reconstruction of the CME has been done using multi viewpoint observations from SOHO, SDO, STEREO-A and STEREO-B. To conclude the picture we investigate in-situ data at around 1 AU and geomagnetic indices near Earth. The influence of the HSS on the CME structure can already be observed from remote sensing white- light data as well as from in-situ data. By understanding the interactions and the relations between CHs and CMEs, we are able to conclude and advance the forecast of space weather effects. To improve the forecast capabilities is in great demand in the space weather community and this study is another step in reaching this goal.

coronal holes, high speed stream, coronal mass ejections

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