Notes on the correlation between SSWs and solar activity

A correlation between solar activity and normalized occurrence rate of sudden stratospheric warmings (SSWs) has been found. As a proxy for solar activity, F10.7 cm radio flux has been used. In order to find the correlation, we derived a normalized occurrence rate of MSSWs based on both ERA40/ERA-Interim dataset and NCEP data. Based on this distribution, we calculated the correlation coefficient, which amounts to 0.6314, with a significance of 90.68 % for ERA40/ERA-Interim, and 0.5455 for NCEP-NCAR-I, with a significance of 83.80 %. Additionally, we calculate correlation coefficients for Lyman-alpha flux and sunspot numbers with the analogous method for the same period.