Statistical Study between Characteristic Parameters of Coronal Holes and Intensity/Time of Geomagnetic Storms

Geomagnetic storm is an important subject in space weather forecasting. High speed solar wind originating from coronal holes passes through the interplanetary space about three days before reaching the Earth. It triggers geomagnetic storms which are dominant during the declining phase and the minimum year of a solar cycle. At present, geomagnetic storms forecasting mostly relies on solar wind parameters at 1 AU, and geomagnetic storms are predicted in advance only by about 1 hour. In order to predict geomagnetic storms much earlier, it is necessary to establish the quantitative relationship between the characteristic parameters of coronal holes and geomagnetic storms from the point of the Sun, which is the source of high speed solar wind and geomagnetic storm. In this study, 152 coronal holes and relevant geomagnetic storms events from May 2010 to December 2016 are analyzed. Two characteristic parameters of coronal holes are extracted based on SDO/AIA images, and the geomagnetic index ap, Dst and AE during geomagnetic storms are analyzed. The statistical relationship between characteristic parameters of coronal holes and intensity/time of geomagnetic storms is established, which provides a basis for predicting geomagnetic storms in advance by 1~3 days based on solar EUV images.