2014, 34(3): 278-286.
doi: 10.11728/cjss2014.03.278
Abstract:
Space Time-Index (STI) plots is a graphical method used for testing dynamical non-stationary in general time series. In this paper, the non-stationary characteristics of the z components of geomagnetic field variations with the improved Space Time-Index (STI) plots method were analyzed, and data under different K indexes, different Lloyd seasons, as well as day and night are used. The result shows that the improved space time-index plots method can effectively test whether dynamical non-stationarity exists in geomagnetic variation field, and there is dynamical non-stationarity in z component. On the other hand, the analysis of the z component from different K-indexes introduces that, with the increase of K-index, the phase space distributions of z component become increasingly more uneven and the time evolution features become more complex. Research on geomagnetic field variation from different Lloyd seasons presents that the shapes of the STI plots of z component from different Lloyd seasons are similar. However, as the decrease of the Sun-Earth distance, the complexity of the time evolution of z component becomes heightened, showing some seasonal variations. And the conclusion obtained from the study of diurnal variation of geomagnetic field is that, fluctuation of the STI plots of z component in night time is more severe than that in daytime, and the diurnal variation of z component is obvious.