Different statistical methods are used to analyze the various possible effects of the solar activity (2800 MC radiation intensity F (2800 MC), SID events), the geomagnetical activity (SSC events, Kp index) and meteorological factors ( Tat 50 mb altitude) on the winter anomaly in the ionospheric absorption of radio waves. The noon fmin
data from the ionosonde in Beijing are taken as the index of the ionospheric absorption.The fmin
(27 days running average) are found to be well related to the F = F-F (21 days running average) and also many noon fmin
> 0.2 MC) are found to follow the strong SIDevents especially in summer. The significant effects of the solar activity, which are not included in the so-called ionospheric absorption anomaly, are removed from the other analysis carefully.From our work, compared with geomagnetical factor the meteorological factor is the favourite one for explaining the anomaly.The superposed epoch method is used to show the relationship between the fmin
event days (as key days) and Kp (the sun of eight numerical planetary Kp indices for each U T. day) as well as T (50mb) (temperature deviation form the 11 days running average). The T (50 mb) are found to increase after the fmin
events without SID, and attained the maximum four days after the key days. That result is in a reasonable agreement with the theory concerning the virtical propagation of the planetary waves from the stratosphere.It seems that SSC and fmin
events are not related closely in our analysis. The relationship between the Kp and the anomaly absorption is somehow ambigious here and need to be studied further.