Study Of Correlation And Regularity Between Geomagnetic Data And GIC Based On Geomagnetic Storms

During the solar activity,high-energy particles carried by the solar wind interact with the magnetosphere ionosphere,and local geomagnetic disturbance causes the induced geoelectric field to generate the geomagnetic induced currents(GIC).In recent years,more and more attention has been paid to the adverse effects of geomagnetic storms on the long-distance ground infrastructure such as pipelines and cables.In this thesis,the correlation between geomagnetic data and GIC during geomagnetic storms is studied.The research results are conducive to accurately predicting GIC,guiding disaster response measures,reducing the impact of geomagnetic storm on production and manufacturing,communication and transmission,and ensuring the stable operation of ground facilities such as pipeline network and power systemFirstly,the relationship between geomagnetic storms,geomagnetic indices and GIC is studied.According to the selected typical geomagnetic storm events,the observation characteristics of geomagnetic data and GIC are analyzed.With the increase of the intensity of geomagnetic activity,the peak value of GIC has a significant increasing trend.It is found that AE index has a positive correlation with GIC,which is stronger than SYM-H index.When GIC data is lack,the change of GIC can be inferred by analyzing the geomagnetic indices,which can provide the reference for early warning of geomagnetic stormsSecondly,based on the data of geomagnetic storms measured by the Finnish station,and the method of Spearman correlation coefficient,the correlation between GIC and dBx/dt is studied.It is extended from single geomagnetic storm event to geomagnetic storms from 1999 to 2017.The fitting coefficient is determined and the empirical model is established.The geomagnetic storm events of 2018 are taken as an example,dBx/dt data is input into the empirical model to predict GIC.The error between the predicted value and the measured value of GIC is calculated and the accuracy of the established empirical model reaches 75.5%.The possibility of quantitative analysis and prediction of GIC based on the empirical model is realizedFinally,based on continuous wavelet transform(CWT)and discrete wavelet transform(DWT),the spectrum characteristics and wavelet coefficients of GIC and dBx/dt are studied in order to study the variation law.The scalogram of typical event shows the high variability and obvious local periodicity of GIC There is a one-to-one correspondence between the wavelet power spectrum and GIC signal.The wavelet coefficients of dBx/dt of geomagnetic storm events in the same period over the years are discussed.Compared with CWT coefficients,DWT low-frequency coefficients of dBx/dt increase significantly,which can represent the variation levelIn conclusion,the study of the correlation and regularity of geomagnetic data and GIC can effectively evaluate the variation of GIC.It can reduce the cost of hardware investment,provide reference for the operation scheduling and disaster prevention of geomagnetic storms,.and ensure the safe operation of infrastructure.