Statistical Study About The Relationships Between Coronal Holes' Parameters And The Correlative Geomagnetic Disturbances

Data from the SOHO EIT284 images are used to analyze the development ofcoronal holes which existed from 1996 through 2005. In order to investigate therelationship between the coronal hole and earth effect, we examined the correlativityamong the coronal holes parameters including coronal holes' area and longitude span,solar wind parameters and geomagnetic index. There are four chapters in this paper:(1) In the first chapter, the properties of coronal hole and interplanetary solar windand correlative recurrent geomagnetic disturbances are discussed. Someresearch conclusions of former researchers are reviewed.(2) Coronal hole boundaries cannot be definitely established because there is nocompletely objective, quantitative observational method for locating them.Here we use SOHO/EIT284 images to extract coronal hole boundaries basedon emission flux density and introduce an algorithm to calculate the coronalholes area exactly.(3) The correlation between coronal holes, interplanetary solar wind and recurrentgeomagnetic disturbances are calculated, and it is found that (1) coronal holesplay great role in geomagnetic storms around solar activity maximum,(2)velocity of solar wind has good correlation with geomagnetic disturbanceintensity,(3) There is poor correlation between coronal hole areas andmaximum interplanetary high speed stream velocities. This is different fromthe result of Nolte, who thought that the linear correlation coefficient is good.We think it must be much more complex.(4) The relationship with coronal holelongitude extend (N20-S20) and geomagnetic disturbance duration is verygood.(4) The last chapter of this paper, some conclusions and discussions are given.