Metallic ions in the equatorial ionosphere.

Journal of Geophysical Research Atmospheres (Impact Factor: 3.44). 03/1973; DOI: 10.1029/JA078i004p00734
Source: NTRS

ABSTRACT Four positive ion composition measurements of the equatorial E region at Thumba, India, are presented. During the day, the major ions between 90 and 125 km are NO+ and O2+. The relative concentrations are similar to those observed at midlatitudes but exhibit unusual structural behavior with altitude. A metallic ion layer centered at 92 km is found to contain Mg+, Fe+, Ca+, K+, Al+, Na+, and possibly Si+ ions. The layer is explained in terms of a similarly shaped altitude distribution of neutral atoms that are photoionized and charge exchanged with NO+ and O2+. Three-body reactions form molecular metallic ions that are rapidly lost by dissociative ion-electron recombination.

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    ABSTRACT: A thin and highly dense sporadic E layer, which can occasionally block the upper ionospheric layers, is called blanketing sporadic E (Esb). We present the statistical seasonal local time occurrence pattern of Esb at equatorial station Tirunelveli (8.7° N, 77.8° E, dip latitude 0.7° N) during the extended minimum of solar cycle 24 (2007–2009). In spite of nearly the same average solar activity during both 2007 and 2009, considerable differences are noticed in the seasonal occurrence of Esb during this period. The percentage of Esb occurrence is found to be the highest during the summer solstice (≥ 50%) for both 2007 and 2009, which is in general accordance with the earlier studies. The occurrences of Esb during the vernal equinox (~ 33%) and January–February (~ 28%) are substantial in 2009 as compared to those during the same seasons in 2007. We find that, during winter (January–February), ~ 75% of Esb occurred during or just after the period of sudden stratospheric warming (SSW). We suggest that enhanced Esb occurrence during winter (January–February) and the vernal equinox of 2009 could be associated with SSW-driven changes in the E region ambient conditions. Furthermore, the close association of Esb with counter equatorial electrojet (CEEJ) suggested by earlier studies is re-examined carefully using the scenario of Esb occurrence on non-CEEJ days. Such an exercise is crucial as we are unaware whether the physical mechanisms driving Esb and CEEJ are linked or not. We find that, of all the seasons, the association of Esb and CEEJ is strongest during winter (November–December).
    Annales Geophysicae 05/2014; DOI:10.5194/angeo-32-553-2014, · 1.68 Impact Factor
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    ABSTRACT: An investigation regarding the occurrence of Si ions is conducted, taking into account an unusual metal ion structure observed during a meteor shower event. Loss processes involving silicon oxides are considered in connection with a study of the reasons for the unique Si(+) distribution found. It is suggested that below 100 km Si(+) is rapidly depleted by two- and three-body reactions with molecular oxygen, forming SiO2(+) which then recombines.
    Radio Science 03/1975; DOI:10.1029/RS010i003p00329 · 1.45 Impact Factor
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    ABSTRACT: Several review papers on D and E region topics appeared during the quadrertnium as follows: the lower ionosphere [Thomas, 1971], theoretical models of the D region [Sechrist, 1972], the relationship of theory and experiment in the D region [Aikin, 1972], E region model parameters [Swider, 1972], progress in ionospheric research [Bowhill, 1973], chemistry of metallic elements in the ionosphere and mesosphere [Brown, 1973], theory of the D region [Thomas, 1974], physics and chemistry of the E region [Strobel, 1974], and lower ionosphere ion chemistry [Sechrist, 1974a]. Although D and E region research has made rapid progress in the past decade, it is evident that as knowledge expands, these regions become more complex physical and chemical systems, and our views appear to be less distinct than before; and aeronomers need to be reminded that the lower ionosphere is an ionospheric region that is hydrodynamically coupled to the lower atmosphere and electrodynamically coupled to the magnetosphere.
    07/1975; 13(3). DOI:10.1029/RG013i003p00894

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