Effect of the geomagnetic storm of April 23, 2012, on the ionospheric total electron content over the Mediteranean Region

Geomagnetic storms are disturbances of the terrestrial magnetic field of several hours with a global character. The origin of this disturbance is the arrival of solar wind disturbed by a coronal mass ejection in which the interplanetary magnetic field has a southward Z component. A geomagnetic storm may result in an ionospheric storm which is mainly characterized by a disturbance of the electron density of the F2-layer of the ionosphere. These ionospheric storms have a major influence on GNSS observables and thus can affect the accuracy in positioning. This work describes the phenomena associated to the geomagnetic storm of 23 of April 2012. The origin was a coronal mass ejection produced the 19th that increased the velocity of the solar wind and changed the interplanetary magnetic field. The arrival of the disturbed solar wind to the Earth triggered a geomagnetic storm that began on 23th and lasted until the 27th. This geomagnetic storm caused an ionospheric storm over Mediterranean region which had several phases whose characteristics depend on latitude, longitude and the stage of the geomagnetic storm in which takes place.