A STATISTICAL STUDY FOR THE SPACIAL-TEMPORAL SCALE OF IONOSPHERIC DISTURBANCES IN MIDDLE CHINA

In this paper the dynamic cross spectral analysis with maximum entropy method is used to yield the spacial-temporal scale and the propagation direction of the ionospheric disturbances from the data of a Doppler array.The obtained parameters of the disturbances are statistically studied,and the results reveal two types of ionospheric disturbances:one is the southward propagated wave which has the large scale on both spacial and temporal domain,the other is the north-eastward wave which has the relatively smaller scale.The sources of the southward waves are related to the polar activeties,and those of the northeastward waves may be located in the easten Qinhai-Tibet Plateau with abruptly swollen topography.The paper concluded that the global and the local properties of the ionospheric disturbances have some thing to do with the polar source and the local source respectively.