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

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 .

Changes in the D region associated with three recent solar eclipses in the South Pacific region

“…The average value (10 points) of α eff comes out to be 5.59 × 10 À7 cm À3 s À1 at 75 km (normal reflection height) and 1.56 × 10 À7 cm À3 s À1 at 80 km. The value of α eff is larger by 24% to the daytime ionospheric quiescent condition value of α eff = 4.5 × 10 À 7 cm À 3 s À 1 [Mitra, 1968] but small compared to nighttime value of [Belrose et al, 1964]. Using the IRI 2012 model for the location of Suva for SE on 9 May at 22:30 UT (10:30 LT), we found N e to be 6.45 × 10 2 cm À3 at the 75 km height which is 23.4% less than that obtained using LWPC modeling at the same height.…”

Effective Recombination Coefficient in the D Region

“…As the various physical processes controlling the steady state distribution of charges in the D region have become better understood, it has been possible to obtain more reasonable estimates of the effective recombination coefficient. There have been many attempts to deduce this coefficient (cx,rr) from observational data in the past [Belrose, Bode, and Hewitt, 1964;Whitten et al, 1965;McDiarmid and Budzinski, 1964;Adams and Masley, 1964]. The object of the present paper is to present the results from another such attempt.…”

Effect of Meteoric Dust on the Effective Recombination Coefficient in the Lower Ionosphere

“…For detailed review and discussion of the processes, reference may be made to Baily [1959]: Webber (1962]: Reid [1963); Whitten and Poppoff [1965]: Biondi (1964]; Fite [1964]: andBranscomb (1964]. Estimates of the effective recombination coefficient have also been made from observational data by Belrose, Bode, and Hewitt [1964]: : and McDiarmid and Budzinski Adams andMasley [1965]: in most of the cases these values are higher than the theoretically derived ones. (Note that the term "effective recombination coefficient" has been used in the literature to represent two dissimilar, but related, concepts.…”