ABSTRACT
This chapter reviews recent literature on the effects of tropical cyclones (TC) on the ionosphere. TCs are sources of acoustic and gravity waves, and of electric fields affecting the ionospheric plasma. Electron density drop (most defined near 70 km) is recorded in the lower ionosphere over a TC area. In the upper ionosphere, TCs can cause both increase and decrease in the electron density, as well as electric field variations. A region of the ionospheric plasma irregularities forms over the cyclone trajectory in the upper ionosphere. This region occurs when the cyclone reaches the hurricane phase, has a ~2000 km horizontal extent, and follows the cyclone. The irregularities are recorded like traveling ionospheric disturbances (TIDs) with 10 min - several hour periods. The issue of the TC effective radius on the ionosphere still requires studying.
