Magnetoionic Multiple Refraction at High Latitudes

Experimental ionospheric soundings examined by Scott and Davies are cited, with a short discussion of the interpretation these authors offer for multiple refraction at high latitudes. The theory of magnetoionic multiple refraction of Appleton and Builder is discussed with especial regard to effects to be expected in high geomagnetic latitudes. Experimental evidence is offered to show that the "Z" component of Scott and Davies is probably the longitudinal ordinary ray predicted by Appleton and Builder and by Taylor when collisional friction is appreciable. On the basis of certain assumptions, the collisional frequency near Fairbanks, Alaska, is calculated as about 4(10)
⁴
at 300 km. height.