It has long been understood that the ionosphere is a very dynamic and difficult region to predict because it is influenced from above by the Sun-Earth environment and from below by energy through wind and waves. The conditions get more complicated during a geomagnetic storm. During geomagnetic storms huge amounts of energy and momentum are injected into higher latitudes in the form of precipitating particles, Joule heating, and/or Lorenz forces which have a potential to trigger large scale and equatorward traveling ionospheric disturbances (TIDs) (Afraimovich et al., 2000;Ngwira et al., 2012). TIDs are quasi-periodic variations of F-region electron densities often associated with atmospheric gravity waves (AGWs). Based on basic wave-related characteristics they can be classified as large scale TIDs (wavelength > 1,000 km, 30 min < period < 180 min and 200 m/s < horizontal speed < 500 m/s) and medium scale TIDS (wavelength <1,000 km, 15 min < period < 60 min and 100 m/s < horizontal speed < 250 m/s). TIDs have been detected for several decades using a number of different instruments, including ionosondes (e.g.,

No abstract

No abstract

No abstract

No abstract