Environmental studies for radar operations in the auroral zone

Abstract

The relations between VHF and UHF radio aurora and geomagnetic activity, as indicated by telluric current records, have been investigated. (VHF and UHF radio aurora are considered in Parts I and II, respectively, of this report.) VHF radio aurora, observed over Barrow, Alaska by a 41 Mc/s radar at Kotzebue, Alaska, and telluric current activity at Barrow show a high correlation, particularly with respect to onsets of major activity. Slight or moderate activity usually gives some forewarning of intense activity, but some disturbances have extremely abrupt onsets of intense activity. The correlation is clearly highest for overhead and nearly overhead radio aurora and drops off for separations of 300 km and more. Incoherent scatter from ionosphere has been recorded by the BMEWS UHF radar at Clear, Alaska by use of two different techniques. A generally applicable procedure is to record radar return for a period of time in analog form on magnetic tape for subsequent processing by a digital computer. The BMEWS radar is also capable of detecting incoherent scatter by the use of “DTO” reports accumulated over a period of time. Conventional ionospheric electron density profiles showing E, F1, and F2 layers, with the highest electron densities in the F2 layer, have been obtained at times. On other occasions the peak in electron density occurs at F1 layer heights. The technique is capable of providing profiles under conditions causing “blackout” of conventional ionosonde recorders.