Some observations of 2.89 mc/s equivalent antenna temperatures at the auroral zone

Abstract

Observations of the noise level on a 2.89 mc/s dipole antenna have been made near College, Alaska, during November, 1959, and January and February, 1960. During noon hours, the signal has the characteristics of thermal noise. Equivalent midday antenna temperatures are in the range 200–1000 °K, and show a negative correlation with K p . It is believed that the lowest values are reasonably accurate measurements of the D region electron temperatures, and that the D region electrons therefore have temperatures comparable with the ambient gas temperatures. The higher values observed during magnetically quiet periods are attributed to reception of oblique incidence cosmic noise, which has penetrated the ionosphere on the night side of the winter polar cap. Occasionally nighttime observations have been possible during aurora; the resultant effective electron kinetic temperatures, of the order 200–250 °K, indicate that the mean kinetic energy of the electrons in the lower part of the absorbing region is not markedly affected by the presence of aurora