No abstract

During the win ter of 1963-64 observation s of partialrefi ectioll S at a frequen cy of 2.66 Mcjs w er e made at R esolutc Bay (in varian t magn etic la t itude 84)1.0) n eal' local midnight. Utili zin g t he d iffer en t amplitudes of the ordin ary and extraordinary backsca ttered waves, in formation was obtained abo ut electron densit ies a nd elec tron collision fr equenci es. E lectron d ensit ies range from 10 cm-3 at 80 Ion to 1000 cm-3 at 110 km. Collis ion fr equency values are a factor of 2-4 t imes greater than average d aytime r es ults at lower latit udes. These obser vation s , together wit h some in direct infer ences based on low frequency propagat ion between Thule and Churchill (in varian t magn etic latitude 79 }~0 at p ath m idpo int) are d iscussed and i t is co ncluded t ha t (1) galactic cos mic rays a re r espon s ible fol' electron produ ct ion below 90 km, (2) ioni zation rates in exccss of ga lac t ic cos mic ray production are r eq ui red for heights above 90 km, (3) effective electron loss r ates below 90 km a re markedly more rap id than di ssociative recombin atio n, and (4) t he po la r winte r mesosphere is ho tter t han previolls data sll ggest .

No abstract

Observations of partial reflections from the ionosphere at vertical incidence at 2.66 MHz have been made at Resolute Bay, geographic latitude 74.7"N, since September 1963. By measuring the amplitudes of the ordinary and extraordinary backscattered waves information is obtained about electron number densities in the lower ionosphere. The results presented in this paper show that the partial reflection technique is more sensitive than most other ground-based experiments for the detection of D-region ionization increases associated with small solar proton events. Results obtained by the partial reflection experiment during the events of 5 February 1965 and 16 July 1966 are presented and compared with VLF and satellite observations.