Physical properties of the polar winter mesosphere obtained from low-frequency propagation and partial reflection studies

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 .