Gaussian random process and its application for detecting the ionospheric disturbances using GPS

Usually, ionospheric Total Electron Content (TEC) variation with time can be viewed as a stationary random process under quiet conditions. However, sudden events of the Sun and the Earth such as solar flare and sudden commencement of geomagnetic storms may induce the disturbances of the ionosphere, so that the stationary random process is broken; the statistical model parameters change much. Based on this fact, here we make use of the time series of TEC and the autocovariance function of the stationary process to construct independent identical distribution Gauss sample so that the 2 χ test can be used to detect the abnormity hidden in the sequence. In addition, GPS data from several IGS sites in China during the severe solar flare occurred on 14th July, 2000 are used to verify the method. The results indicate that the disturbances caused by the solar flare can be effectively detected.