Optimum parameter for estimating phase fluctuations on transionospheric signals at high latitudes

Transionospheric radio signals may experience fluctuations in their amplitude and phase due to irregularity in the spatial electron density distribution, referred to as scintillation. Ionospheric scintillation is responsible for transionospheric signal degradation that can affect the performance of satellite based navigation systems. Usually, the scintillation activity is measured by means of indices such as the normalised standard deviation of the received intensity S(4) and the standard deviation of the received phase sigma(phi) typically calculated over 1 mm of data. Data from a GPS scintillation monitor based on 50 Hz measurements recorded at Dirigibile Italia Station (Ny-Alesund, Svalbard), in the frame of the ISACCO project (De Franceschi et al., 2006) are used to investigate possible adoption of an alternative parameter for the estimate of phase fluctuations: i.e., the standard deviation of the phase rate of change S(phi). This parameter is shown to better correlate with S(4) being much less detrending dependent than sigma(phi). The couple (S(4), S(phi)) should be then considered a more physical proxy of radio scintillation than the couple (S(4), sigma(phi)). (C) 2010 Published by Elsevier Ltd. on behalf of COSPAR.