The Coronal Holes and Geomagnetic Indices within the 22nd Solar Cycle Period

Statistics of coronal holes and geomagnetic indices in the solar medium and low latitude areas during the 22nd solar cycle are period presented in this paper.The periodogram analysis of the coronal holes and geomagnetic indices in such time separations as month, quarter, yera in the cycle are given together.The results are listed as follows: (1) The correlativity between coronal holes and geomagnetic indices during the 22nd solar cycle is shown to be positive.The general tendency is that the index A reaches maximum on the third day after the central meridian passage (CMP) of the coronal holes.(2) The correlativity in question during the months within solar inactive period is better than that within active one ,and the index A reaches maximumm on the foruth day after the CMP of coronal holes.(3) Coronal holes and geomagnetic indices are correlated in the ascending years, peak years, descending years during the 22nd period of solar activity.Nevertheless, the dates when index A reaches maximum after the CMP of coronal holes are different.It is worthy of note that the index A becomes maximum delayingly on the fifth day after the CMP of coronal holes in peak years.(4) The correlativity between coronal holes and geomagnetic indices shows a quarterly effect apparently.(5) The correlativity in question is weakened by the flares of high energy X-rays.