On the Correlation of Radio Transmission with Solar 



Phenomena * 



By A. M. SKELLETT 



A 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 York- 

 London 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 un- 

 commercial 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. For instance it would be possible to 

 predict the radio behavior from the magnetic chart alone. This 

 method has been found to yield the same order of accuracy as that 

 using the radio chart alone. 



Daily predictions of the behavior of the radio circuits from either the 

 radio or magnetic chart have been correct 62 per cent of the time. 

 Similar predictions of the magnetic data from the magnetic chart have 



* Digest of a paper presented at the Sixteenth Annual Meeting of the American 

 Geophysical Union, Washington, D. C, April 25, 1935, and published in full in the 

 Proceedings of the Institute of Radio Engineers, November, 1935. 



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