论文部分内容阅读
In this paper, we present further observational evidences for the trans-polar propagation of Large-Scale Traveling Ionospheric Disturbances (LSTIDs) from their nightside source region to the dayside reported by Cai et al.(2011).Slant Total Electron Content (STEC) observed by longitudinally-aligned GPS receiver chains in North American and European sectors were analyzed to demonstrate presences of LSTIDs at both nightside and dayside mid-latitude.Signatures of TID were inferred from phase difference in time series of STEC perturbations (TECP) derived from measurements of ground-based GPS receivers, which are separated by hundreds kilometer longitudinally.Periods of the day-time and night-time ionospheric disturbances were estimated to be around 128 minutes, being in good agreement with that of the trans-polar AGW recorded by EISCAT/ESR radars.On the dayside, the LSTID moved equatorward with an average phase speed of~440 m/s.In North American sector, however, southward speed of the night-time LSTID was much slower, being around 160 m/s.We suggest that the observed day-time and night-time mid-latitude LSTIDs are likely to have the same source region, being located somewhere at night-time auroral latitude.Having been launched on the nightside, the waves propagate simultaneously equatorward and poleward.The equatorward moving waves are recorded by GPS receiver chain in North American sector.The poleward-moving waves, however, cross the polar cap from nightside to dayside and then are detected consecutively at high-and mid-latitudes by EISCAT/ESR radars and GPS receiver chains, respectively.