Geoscience Reference
In-Depth Information
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Local time starting January 3, 1981
Figure 5.23 Altitude variation of a number of layers detected during a 78 h period over
Arecibo. (Figure courtesy of Q. H. Zhou.)
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Geographic longitude (8)
Figure 5.24a Contours of temperature perturbation for the diurnal tide on which the
equatorial vertical drift is superposed. [After Kil et al. (2007). Reproducedwith permission
of the American Geophysical Union.] See Color Plate 10.
In summary, the electrodynamics of the midlatitude ionosphere are controlled
by tidal and higher-frequency atmospheric wave modes in the E-region during the
day. At night a very complex combination of the thermospheric wind dynamo,
high-latitude electric field penetration, conjugate hemisphere effects, and gravity
waves all play a role. These effects are modulated by a strong diurnal variation in
theE-regionconductivitywhichallows theF-layerdynamotogaincontrol atnight.
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