Abstract:
The correlation between the presence of coronal holes and flare indices has been inves-
tigated for the period from 1976 to 1995. The analysis shows that in the cases of 227 Carrington
rotations (CRs) backward time lags yield the highest correlation between the coronal holes and
flare indices. The maximum correlations were found at time lags of 222 and 142 CRs for polar
and equatorial coronal holes, respectively. The period of study covers the past two solar cycles (21
and 22). Correlation analysis of both solar cycles has also been studied individually. The correlation
analysis reveals that there is in general a forward shift in the maximum correlation for polar coronal
holes, but it cannot be recommended to use polar coronal hole numbers for forecasting the next solar
cycle.
