Extraction of secular variation signals of geomagnetic field and evaluation of prediction accuracy of geomagnetic field models

The purpose of this research is to compare the secular variations of the core field calculated by IGRF and WMM with those observed by geomagnetic stations and to quantitatively evaluate the accuracy of IGRF-12 and WMM2015 in mainland China. Based on the hourly mean data of 10 geomagnetic reference stations in mainland China from 2009 to 2022, we used annual differences of monthly means and principal component analysis to eliminate the external interference field and remove the crustal magnetic field to extract the secular variation of the core field. The results are the prediction accuracy of the seven geomagnetic elements in the WMM2015 model is better than that of IGRF-12, and the error will gradually increase with time. The maximum 1-year error of the total field intensity of the two models is 13 nT, and the 5-year error reaches 153.65 nT, which is difficult to meet the requirements of high-precision geomagnetic navigation. It is suggested to develop the rapid secular variation model (1 year) to improve its prediction accuracy by supplementing the multi-source magnetic survey data in China.