Geomagnetic activity and occurrence of sporadicEin the Far East

The correlation between occurrence of sporadic E and magnetic activity has been reported to be zero up to 30°N geomagnetic latitude by Smith and Thomas and Smith. Because there are large gaps between stations in this region, however, Smith has noted that the situation is not clear below about 20°N. In the present paper, using the data obtained during ten summer months of IGY and IGC 1959 for the stations in the Far East, three of which are located below about 20°N, we show that a positive correlation exists from 5°N to 30°N geomagnetic latitude, and that the correlation becomes negative around 30°N. The diurnal variation of geomagnetic effect on the occurrence of Es is also investigated.