The polar ionosphere is sensible to the enhancement of the electromagnetic radiation and energetic particles coming from the Sun expecially around a maximum of solar activity . Some typical phenomena can occur such as, among the others, geomagnetic storms, sub-storms and ionospheric irregularities. In this frame the high latitude 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 kilometers) ambient ionosphere. These irregularities produce short term phase and amplitude fluctuations in the carrier of the radio waves which pass through them. These effects are commonly called Amplitude and Phase Ionospheric Scintillations that can affect the reliability of GPS navigational systems and satellite communications. The goal of this proposal is to contribute to the understanding of the physical mechanisms responsible of the ionospheric scintillations as well as to data collecting for nowcasting/forecasting purposes at high latitude. As the scarceness of polar observations, the specific site near Ny-Ålesund is of particular experimental interest.
Two scintillation and TEC monitoring receivers closely spaced (sub-km) are working since September 2003 at Nyalesund(78.9N;11.9E). They provide true amplitude, single frequency carrier phase measurements and TEC measurements from up to 11 GPS satellites in view and can also track one SBAS (WAAS, EGNOS or MSAS) satellite, providing L1 measurements and data. The software automatically compute and log the amplitude scintillation index, S4, and phase scintillation index, sf, computed over 1, 3, 10, 30 and 60 seconds. In addition, TEC and TEC phase are each logged every 15 seconds. Phase and amplitude data, either in raw form or de-trended (to remove systematic variations), can also be logged at a 50-Hz rate.
Ionospheric scintillation and TEC monitoring is also performed by the Canadian GPS network for Ionosphere Monitoring (CANGIM)at Calgary (51.08N;114.13W), Athabaska (54.72N; 113.31W), Yellowknife (62.48N;114.48W). Since 2004 the University of Bath (UK) operates a number of Novatel GPS receivers for TEC and scintillation monitoring based at the sites of the European Incoherent Scatter (EISCAT) radar in Tromso (Norway), Kiruna (Sweden) and Sodankyla (Finland). Three receivers are closely spaced (sub-km) and the other three are far apart (hundreds of km) to monitor ionospheric scintillation on multiple scale length baselines.