Solar coronal holes and their geo-effectiveness

Abstract

Solar corona as the outermost part of the Sun is constantly emanating solar wind consisting of charged particles. Coronal holes are rigidly rotating phenomena in the solar corona that are magnetically open to interplanetary space, which allow the solar wind particles to escape from the Sun. The study of coronal holes and their associated high speed solar wind streams is important because they are the sources of space weather disturbances during minimum solar activity. We present some results on the relationship between large solar coronal holes close to the central meridian and solar wind stream with the aim to analyse their geo-effectiveness. The analysis were carried out by considering geomagnetic and solar wind parameters such as total geomagnetic field, Bz component, proton density and plasma speed during Earth-side large solar coronal holes appearance. Using the data during declining phase solar activity we found that a solar coronal hole is geo-effective during and after its transit on the central meridian but not all of them can be the proxy of high speed solar wind.