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The global distribution of the dusk‐to‐nighttime enhancement of summer N m F 2 at solar minimum
Author(s) -
Chen Yiding,
Liu Libo,
Le Huijun,
Wan Weixing,
Zhang Hui
Publication year - 2016
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2016ja022670
Subject(s) - southern hemisphere , northern hemisphere , sunset , atmospheric sciences , earth's magnetic field , dusk , latitude , ionosphere , environmental science , climatology , declination , daytime , solstice , physics , geology , astrophysics , geophysics , astronomy , magnetic field , quantum mechanics
In this paper, the dusk‐to‐nighttime enhancement (DNE) of summer N m F 2 was investigated based on Constellation Observing System for Meteorology, Ionosphere, and Climate radio occultation observations at solar minimum. The global distributions of the magnitude and the peak time of the DNE as well as the role of the DNE in N m F 2 diurnal cycle were presented. The DNE mainly exists in three regions (one in the Southern Hemisphere and two in the Northern Hemisphere), and its distribution is related to geomagnetic configuration, especially in the Southern Hemisphere. For most DNEs, their peaks correspond to the maxima of N m F 2 diurnal cycle. The DNEs are much more prominent in the southern than in the northern summer hemisphere; they last to later nighttime hours, have larger magnitudes, and play more important roles in N m F 2 diurnal cycle in the southern than in the northern summer hemisphere. The distribution of the DNE was analyzed in terms of photoionization and the vertical plasma drift induced by neutral winds. The positive geomagnetic declinations and the smaller geomagnetic inclinations at higher geographic latitudes over the South Pacific are crucial for the prominent DNEs in the southern summer hemisphere; they result in larger upward plasma drift at higher latitudes where photoionization is still significant at sunset and evening hours.