Propagation of HF and VHF in the Arctic Region

All the available ionospheric records for stations located north of 60° geographic latitude and for the period 1954 to 1957 were critically analyzed. The F2 region shows two distinct types: one, north of 75° with very little or no diurnal and seasonal variation in the critical frequency; the second, south of 70°N, exhibits diurnal and seasonal variations as well as those correlated with sunspot activity. Communication by means of abnormal ionization, such as Es, is known. We found three types of sporadic E abnormalities; namely, the Thule type, the Auroral-Belt type, and the Mixed type. These types show a distinct geographic distribution which is of utmost importance for planning communication links within the Arctic as well as between continental U. S. and the Arctic. Auroras can be used as reflectors or scatterers.