The Production of Geomagnetic Activity: The Activity of the Years 1941 and 1942

In the latter half of the year 1943 multiply recurrent geomagnetic activity was conspicuous.It can be followed for some months into 1944 and can be traced backward, somewhat less clearly, to the beginning of the year 1943.In contrast, the activity of 1941 and much of 1942 exhibits less evidence of such recurrent character.It appears possible, however, by working backward from the recurrent material of 1943, to explain most of the activity of 1941 and 1942 in a manner similar to that used for the activity of 1943 and 1944. 1 We have emphasized that the dynamo theory