Abnormal features of the F₂region of the ionosphere at some southern high-latitude stations

The paper describes some abnormal features of the F2 layer at high-latitude stations in the southern hemisphere. The variation of the midday value of the critical frequency of the F2 layer (foF2) with magnetic dip shows assymmetry between the northern and southern stations of the west (American) zone, but not of the east zone. The control by the earth's magnetic field is indicated in the latitudinal distribution of even the midnight values of foF2. The diurnal variation of foF2. at Port Lockroy shows abnormal minimum at midday and maximum at midnight during the summer months. These abnormal features of the F2 layer at Port Lockroy are explained on the basis of the horizontal transport of ionization as guided by the earth's magnetic field.