Properties of the outer ionosphere deduced from nose whistlers

Abstract

Data from a number of nose whistlers indicate that the electron density in the outer ionosphere is directly proportional to magnetic field strength. The density has an annual variation of 2∶1 with a maximum near December. The average electron density is given approximately by N = 12,000 ƒH, where N is the electron density per cubic meter and ƒH is the gyrofrequency in cycles per second. Local variations as large as 40 per cent are shown to exist on occasion.