The Spatial Field Based Abrupt Change Detection Methods And Their Applications To The TEC Variation Of The Ionosphere

The detection technologies and methods of abrupt change (AC) have experience great developments since the foundation of the AC theory, along with their applications in the studies of AC phenomena in space weather and climate system. The rapid and accurate detection of AC is helpful in understanding the changes of the climate system and forecasting its evolution, and thus, has great theoretical and economic impacts. The existing AC detection technologies are based on long-term observations, and the detection are of great lag in time. In addition, the AC detection of multi-dimensional spatial field still stay at the level of single point detection, ignoring the spatial correlation among the subsystems in the real system (such as climate system).In this paper, the AC detection method of the spatial field based on the spatial correlation characteristics of the spatio-temporal evolution of the system has been proposed. The two-dimensional detrended fluctuation analysis (TD-DFA) method and the two-dimensional rescaled range (TD-R/S) analysis method are used to calculate quantitatively the long range correlation of two-dimensional spatial field, for detecting the AC in the system. The testing results based on these two kinds of spatio-temporal distribution dynamical coupling model show that both of the TD-DFA method and the TD-R/S analysis method can effectively detect the AC in the systems. Furthermore, we study the variation of the global ionospheric total electron content (TEC) by using TD-DFA method, and characterize the diurnal variation, seasonal variation and response to the geomagnetic storms about TEC quantitatively.The detection method of spatial field AC proposed in this paper contain more spatial correlation information than those based only on single point time series, and thus, can effectively reduce the detection time for AC events. Our methods are helpful in quick response to the new challenges induced by the ACs in space weather and climate systems.