Stratification in the lower ionosphere

Abstract

A su rvey of tile eviden ce fo r strat ifi cation in t h E' ionosphere below 100 km is given , cove ring r ad io a nd op tical obse rvations, and r ocket meas ureme nts. T he concl usion is rcached t hat one stratu m at abo ut 85 km is obser ved co ns istently , a nd that other fin e str uct ure exists bu t h as n o long• Lime co nstancy of he ig ht 0 1' p attern . There is n o ser ies of prcferre d heights below 100 km . The au t hors cons ider expla nat ions w hi ch m ay accOLl nt for t h e obsen 'ations, an d a d vocate t he tes ti ng of radio meLhods of exploratio n i;l con ju nction with r ocket meaSl1l'em ents i n order to ci evelop t he m ost p ract icable mealls of obtain in g acc urate electr on d ensity versus height p rofi les on a synoptic basis.

A review of some recent work on mid-latitude spread-F occurrence as detected by ionosondes.

“…Various methods of detection have been used, but most of the investigations have involved rocket flights (see e.g., WHALE, 1951;ELLYETT and WATTS, 1959;BEDINGER et al,1968). Further, experimental evidence of small-scale stratifications was found recently in two middle-atmosphere regions.…”

Radio wave reflections from the mesophere: 1. Heights of occurrence

“…To assist the discussion below, a typical result for September 1956, is shown in Figure 8 In the discussion below, the question of horizontal stratification of partially reflecting regions is considered. Reference may therefore be made to a comprehensive survey of available information relating to stratification in the lower ionosphere by Ellyett and Watts [1959]. These writers interpret stratification to include any phenomenon tending to localized or show maxima at one or more heights.…”

MF and HF radar techniques for investigating the dynamics and structure of the 50 to 110 km height region: a review

“…These early observations were all obtained from low frequencies (LF, to HF and are summarized in Ellyett (1947) and Ellyett and Watts (1959). The first unequivocal indications of radar that returns from heights near but below the E region appear to be those presented by Appleton and Piddington (1938).…”