Comparison And Analysis Of Ionospheric Scintillation Measurements And Predictions Over Sanya And Wuhan

Ionospheric scintillation, which manifests itself as increased noise on a radio signal intensity, phase and arrival angle, is caused by small-scale variations in the ionospheric electron density along a transionospheric propagation path between the transmitter and receiver. Phenomenologically, scintillation effects are most severe at high latitudes and in the equatorial region. It's related to local time, the season and solar activity. Effects on systems range from loss of signal in deep fades, which can cause loss of information or even loss of lock on the signal in phase-sensitive systems (such as deep-space radars) due to phase scintillation. As the dependence of navigation and communication on space environment increasing, the monitoring and forecasting of ionospheric scintillation become more and more important.GPS signal can take the information of ionospheric irregularities when it travels through the ionosphere. Detecting the ionospheric scintillation by using this principle is a convenient and effective way of ionosphere monitoring. In 2002 and 2004, the ionospheric scintillation monitoring and analysis systems were set up in Wuhan and Sanya respectively, and we have get a large account of data. Nowadays, combining the measurements and radio wave scintillation theory to predict ionsopheric scintillation has been paid special attention. Some ionospheric scintillation models have been established. But none of them has the data support of China region, and the validation in China region has not been reported. Therefore, in this paper we introduce the Global Ionospheric Scintillation Model (GISM) and compare the measurements and predictions to evaluate the validation of GISM in China region.In this paper we first deduce the principle of ionospheric scintillation observation and prediction, then introduce the realtime observation system installed in our observatory and the principle, realization and application of GISM. After that, we analyze the measurements in Sanya and Wuhan and predictions of GISM by comparing the intensity and phase scintillation indices in seasonal, diurnal variation and spatial distribution. The validation of GISM in China region has been shown.In the south of China, The results of amplitude scintillation show good overall agreement between GISM predictions and observations in seasonal, diurnal variation and spatial distribution. In seasonal variation, GISM predictions agree in general with observations at moderate scintillation level, but there is more deviation at weak or strong scintillation level. In diurnal variation, GISM predictions accord with observations on the whole, except for a delay of about one hour in the occurrence beginning and maximum. In spatial distribution, observations and predictions all show that occurrence to the south of Sanya is higher than that to the north.The predictions of phase scintillation in the south of China is not as good as that of amplitude scintillation. In seasonal variation, measurements show a maximum of occurrence in winter while prediction show a maximum in equinoctial season. In diurnal variation, measurements show scintillation occurs before sunset, and has a maximum in 21:00, but predictions show a delay of 1 hour. Predicted scintillation mainly occurs in a azimuth of 110°? 240°, and occurrence becomes smaller when elevation increases. But measurements don't exhibit this feature.In the central of China, predictions of amplitude scintillation show the same equinoctial maximum in seasonal variation as that of measurements. Comparing to the measurements,predicted amplitude scintillation begins later, ends earlier,and has a distinct maximum, mainly occurs in specific range of azimuth and elevation.The results of phase scintillation in the central of China is similar to that of amplitude scintillation of this area. Predictions accord with measurements in seasonal variation, but have much more deviation in diurnal variation and spatial distribution. On the whole, the validation in equatorial anomaly is higher than in mid-low latitude area, the agreement in intensity scintillation indices is much higher than that of phase scintillation indices.In the paper we also discuss the reason of this phenomenon. The geomagnetism activity, which is reported by many researchers to inhibit the ionospheric scintillation, is not taken into account in this model. Moreover, the model is based on the European–Atlantic area measurements, which is lack of east Asian measurements'supporting.