A Theoretical Study of the Global F Region for June Solstice, Solar Maximum, and Low Magnetic Activity
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 90, NO. A6, PAGES 5285-5298, JUNE 1, 1985 A Theoretical Study of the Global F Region for June Solstice, Solar Maximum, and Low Magnetic Activity J. J. SOJKA AND R. W. SCHUNK Center for Atmospheric and Space Sciences, Utah State University. Logan We constructed a time-dependent, three-dimensional, multi-ion numerical model of the global ionosphere at F region altitudes. The model takes account of all the processes included in the existing regional models of the ionosphere. The inputs needed for our global model are the neutral temperature, composition, and wind; the magnetospheric and equato ~ ial . electric field distributions; th.e auror!l precipitation pattern; the solar EUV spectrum; and a magnetic field model. The model produces IOn (NO , O ~ , N ~, N+, 0+, He +) density distributions as a function of time. For our first global study, we selected solar maximum. low geomagnetic activity, and June solstice conditions. From this study we found the following: (I) The global ionosphere exhibits an appreciable UT variation, with the largest variation occurring in the southern winter hemisphere; (2) At a given time, Nm F2 varies by almost three orders of magnitude over the globe, with the largest densities (5 x 106 cm-J) occurring in the equatorial region and. t~e lo~est (7. x 10J cm-J) in the southern hemisphere mid-latitude trough; (3) Our Appleton peak charactenstlcs differ shghtly from those obtained in previous model studies owing to our adopted equatorial electric field distribution, but the existing data are not sufficient to resolve the differences between the models; (4) Interhemispheric flow has an appreciable effect on the F region below about 25 0 magnetic la.titude; (5) In the southern wi~ter hemisphere, the mid-latitude trough nearly circles the globe.
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