Recent work on mid-latitude and equatorial sporadic-E |
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| Affiliation: | 1. A.M. Obukhov Institute of Atmospheric Physics RAS, 119017 Moscow, Russia;2. Institute of Solar-Terrestrial Physics SB RAS, 664033 Irkutsk, Russia;3. Swedish Institute of Space Physics, SE-98128 Kiruna, Sweden;4. Space Research Institute RAS, 117997 Moscow, Russia;1. School of Remote Sensing and Geomatics Engineering, Nanjing University of Information Science and Technology, Nanjing 210044, China;2. INGV – Istituto Nazionale di Geofisica e Vulcanologia (National Institute of Geophysics and Volcanology), Rome, Italy;3. Institute of Crustal Dynamics, China Earthquake Administration, Beijing, China;4. ASI, Italian Space Agency, Rome, Italy;5. SpacEarth Technology, Rome, Italy;1. Udaipur Solar Observatory/Physical Research Laboratory, Udaipur 313001, India;2. Departmentof Electronics and Communication Engineering, Tripura University, Agartala 799022, India;3. Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005, India |
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| Abstract: | Theoretical and experimental work since 1970 is summarized. Mid-latitude sporadic-E is most likely due to a vertical shear in the horizontal east-west wind and this theory accounts for the detailed observations of the wind and electron density profiles. Preferred heights of sporadic-E are separated by about 6km and descending layers are often seen moving down with velocities in the range 0.6–4 ms−. Sometimes sporadic-E layers are very flat and uniform, and at other times form clouds of electrons 2–100km in size moving horizontally at 20–130 ms−1. Sporadic-E is probably not correlated with meteor showers; this is a rather surprising result since the ions are meteor debris.The major problems with windshear theory are to account for the dramatic seasonal variation and, to a lesser extent, for the geographical and diurnal distributions.The Q-type equatorial sporadic-E appears to be due to the gradient instability. There is a very much smaller amount of new experimental data available in this area. |
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