ISACCO: an Italian project to monitor the high latitudes ionosphere by means of GPS receivers

Abstract

As the high latitude ionosphere is directly connected with outer space by means of the field line reconnection of the geomagnetic field through the magnetopause, it is highly sensitive to the enhancement of the electromagnetic radiation and energetic particles coming from the Sun. Under such conditions the ionosphere may become highly turbulent showing the presence of small-scale (from centimetres to meters) structures or irregularities imbedded in the large-scale (tens of kilometres) ambient ionosphere. These irregularities can produce short-term phase and amplitude fluctuations in the carrier frequency of the radio waves which pass through them, commonly called ionospheric amplitude and phase scintillations (see, e.g., Morrissey et al. 2004, and references therein). The high latitude ionosphere encounters significant fading, with the most intense fading depths in the polar cap regions and less intense fading in the auroral regions. Severe amplitude fading and strong phase scintillation affect the reliability of GPS navigational systems and satellite communications. As the scarceness of a continuous and systematic monitoring of ionospheric scintillations over polar and auroral regions, the deployment of network(s) of GPS receivers, opportunely configured to observe the ionosphere under quiet and stormy conditions, could represent an important achievement for both space weather purposes and scientific aims. In this paper, a general overview on ISACCO (Ionospheric Scintillations Arctic Campaign Coordinated Observation) is given. ISACCO is an Italian project to monitor ionospheric scintillations at polar regions by means of modified GPS receivers. After some historical and technical notes on the project, the paper presents examples of some of our current investigations based on the data acquired during the almost 3 years of the ISACCO project.