Detection of sporadic E layers over the Eastern Mediterranean

Sporadic E layer is an ionospheric phenomenon which has been classified as an E region (90-150 km) irregularity described by thin layers of extremely dense ionization patches which can significantly affect radio wave propagation. Especially in the case of Cyprus complete blocking of HF signals emanating from short and long-distance HF signals has been observed around noon during the summer. Sporadic E layer can occur during daytime or night-time, and its characteristics vary with latitude. The generating mechanism of the phenomenon has been explained within the general concept of neutral atmosphere-ionosphere coupling and in accordance to windshear theory where long-lived metal ions in the lower thermosphere move vertically to converge into dense plasma layers under the combined action of ion-neutral collisional coupling and geomagnetic Lorentz forcing driven by vertical shears in the horizontal wind. Sporadic E layer formation has been correlated in literature with solar activity, geomagnetic activity and associated to thunderstorms and meteor showers.