The morphology of high‐latitude VHF scintillation near 70°W

Abstract

The long‐term VHF scintillation data from ATS 3 obtained at three stations situated in the North Atlantic sector at auroral and subauroral locations during the period 1968–1974 are used to determine the morphology of high‐latitude scintillations near the 70°W longitude sector. The variation of the average level of scintillation at each observatory is studied as a function of time of day, season, and magnetic activity in a manner suitable for incorporation into statistical models of scintillation occurrence. The most prominent feature of the data is a seasonal dependence of scintillations with a 2:1 variation from northern summer to winter under quiet magnetic conditions. This also causes a large variation in the latitudinal gradient of scintillations from 2 dB per degree in summer to 1 dB per degree in winter for latitudes >60° invariant. The observed seasonal control of scintillations is related to the variation of the tilt angle of the earth's magnetic dipole and consequent modulation of the particle precipitation in the North Atlantic sector of the auroral oval.