Critical Frequencies and Virtual Heights of the Ionosphere, Observed by the National Bureau of Standards at Washington, D.C., July to September, 1941

Abstract

The following ionosphere data are in continuation of those published in each issue of the JOURNAL since 1936.The data given in Table 1 are similar to, but not the same as, those published in the form of graphs by the National Bureau of Standards each month in Proceedings of the Institute of Radio Engineers. The averages given there are for undisturbed days while those given here (Table 1) are for all days of the month. The midnight and noon values given for each day in Table 2 are equivalent to the Bureau's values given in code‐for m in the weekly Ursigrams issued by Science Service.