Tropical twilight HeI 10830 emission |
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| Authors: | NR Teixeira PD Angreji Y Sahai BA Tinsley AB Christensen |
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| Institution: | Instituto de Pesquisas Espaciais, São José dos Campos, Brasil;University of Texas, Dallas, Richardson, Texas 75080, U.S.A. |
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| Abstract: | A further year's observation of twilight Hel 10830 Å emission made in Brazil confirms the trend of seasonal variation found earlier. The 10830 intensities taken with concurrent ionosonde data are discussed in the context of recent model calculations of the emission rates. An increase with KP is attributable to changing production and loss rates of He 23S with changing thermospheric temperature. The morning intensities being greater than those of the evening can be due to several effects, an important one of which appears to be the much greater loss rate of photoelectron energy to ambient electrons in the evening, arising from the very high evening electron concentrations at the Appleton Anomaly ionization crests. |
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