Technical Digests---On the Correlation of Radio Transmission with Solar Phenomena

DAILY character figure for radio transmission is obtained from the data of the short-wave transatlantic telephone circuits of the American Telephone and Telegraph Company. The New YorkLondon circuits are in practically continual use so that they furnish data from which a character figure, representative of the whole 24 hours, may be derived. Such figures are based on the ratio of uncommercial to total time and thus are indirectly dependent on field strengths. In order to facilitate plotting, these character figures were reduced to 3 group indices. Figure 1 shows the indices arranged to bring out the twenty-seven-day recurrence tendency. This is demonstrated by the apparent bunching of the spots into more or less vertical columns. Terrestrial magnetic data are shown alongside in similar form for comparison. The recurrence tendency is well enough marked in the chart so that useful predictions of future behavior may be made. The chart is kept up to date and then by inspection a prediction may be made for any day not more than twenty-seven days distant. Some idea of the probable accuracy may also be obtained from the chart by noting whether the day in question falls, for instance, in the middle of a major sequence or on the ragged edge of a poorly defined one. Such probable accuracy is expressed by modification of the prediction with the words "probably" or "possibly." The correlation between the two phenomena is good enough so that predictions of activity of one nature may be made from the chart of the other type of activity.