Study On Ionospheric Scintillation Characteristics In The High Latitudes Of The Northern Hemisphere

The ionospheric scintillation is mainly concentrated near the equator and high latitudes,and has an important impact on the navigation system positioning accuracy and the reliability of the civil aviation system.With the demand for high-precision and high-reliability satellite navigation and positioning systems,it is particularly important to conduct comprehensive ionospheric research.Long-term ionospheric scintillation analysis of multiple stations with high latitudes was limited by various factors.In the present study,the temporal and spatial variation of ionospheric scintillation at high latitudes of the northern hemisphere is analyzed based on the 11 ionospheric scintillation monitoring stations over Canada region during a 4-year period starting from 2015 using both the ionospheric phase scintillation index and ionospheric TEC fluctuation data.The effect of geomagnetic activity on ionospheric phase scintillation at different latitudes is analyzed in detail.At the last,it is discussed that the impact of geomagnetic storm on ionosphere variability and GNSS positioning application in high latitudes of the norther hemisphere on August 26,2018.The research content contains the following conclusions:1.From 2015 to 2018,the annual rate of phase scintillation at each station is gradually reduced.The phase scintillation in March/September are more pronounced than that in June/December solstices in 2017,which presents a notably seasonal variation.But in 2018 there isn't a good seasonal variation.The occurrence of phase scintillation shows close correlation with local time and latitudinal location.The greater the value of latitudinal location is,the local time will forward.2.Another important point in this paper is that distribution of phase scintillation stays stable according to the altitude and azimuth angles during the researched time span.There is a larger value of phase scintillation occurrence rate in the satellite elevation angle in range of 0°-20° and 70°-90°,and that the frequency of phase scintillation in the 80°-90° satellite elevation angle range is the largest on stations with a geographic latitude greater than 60°.However,the azimuth range of satellites with higher phase scintillation rate is different at different latitude stations.The stations with the low-and high-latitudes have the highest incidence of scintillation in the north-and south-directions.The phase scintillation of most other stations is concentrated in the south and north directions,and rarely occurs around the east-west direction.3.The incidence of ionospheric phase scintillation is positively correlated with the intensity of geomagnetic activity on stations in the geographic latitude 56°-64°,and the maximum correlation coefficient is 0.91.During the geomagnetic storm on August 26,2018,the largest anomalous TEC values in the global and Canadian regions during the geomagnetic storm are 20 TECU and 6 TECU,respectively.The incidence of phase scintillation reaches the highest point about 12.7% at high latitudes,whereas that of geomagnetic quiet period is only 1%.It is consistent with the third conclusion in the above.Furthermore,ROTI variations is similar to phase scintillation index.In addition,the relationship between ionospheric scintillation and positioning accuracy has been analyzed by means of PPP(precise point positioning)method,which proved that in the no phase scintillation period,the root mean square error(RMS)of the positioning error in the horizontal and vertical directions neither exceeds 0.4m.When the phase scintillation occurs,the RMS of the positioning error in the horizontal direction is about 0.7m,whereas the vertical direction is about 1.7m,which indicated thatthe positioning errors is negatively correlated with the intensity of ionospheric scintillation.