[P-EM10] Coupling Processes in the Atmosphere-Ionosphere System

[PEM10-P15] Relation of sporadic E-layer parameters to spread-F generation in the nighttime low- and mid-latitude ionospheres during solar minimum

*Chien-Chih Lee^1,3、W. S. Chen² (1.General Education Center, Chien Hsin University of Science and Technology、2.Graduate Institute of Space Science, National Central University, Jhongli, Taiwan、3.Department of Applied Geomatics, Chien Hsin University of Science and Technology, Jhongli, Taiwan)

キーワード：sporadic E, spread F

In this work, we examine the relation of Es-layer parameters to spread-F generation in the nighttime ionospheres at low- and mid-latitudes during 1996. The data of Es-layer parameters and spread-F are obtained from the Chungli (24.9°N, 121.2°E) and Kokubunji (35.7°N, 139.5°E) ionograms. The Es-layer parameters include foEs (critical frequency of Es-layer), fbEs (blanketing frequency of Es-layer), and Δf (=foEs-fbEs). After the pre-midnight and post-midnight data are classified by seasons, the Es-layer and spread-F events are categorized into each frequency interval of Es-layer parameters. At Chungli, an increasing trend is found in post-midnight of all three seasons, for the occurrence probabilities of spread-F versus foEs. For the occurrence probabilities of spread-F versus Δf, the increasing trend also exists in pre-midnight of the J-months and in post-midnight of all seasons. The increasing trends can be found in the results at Kokubunji, for the occurrence probabilities of spread-F versus foEs and Δf. The increasing trends indicate that polarization electric fields generated in Es-layer can assist to produce spread-F, through the electrodynamical coupling of Es-layer and F-region On the other hand, the results of fbEs show that fbEs is irrelevant to the spread-F generation.