Research of geomagnetic spatial-temporal variations in China by the NOC method
应用NOC方法研究中国地区地磁时空变化

The geomagnetic data at 36 observatories in China during 1995~2006 were calculated by using the natural orthogonal component (NOC) method. We have obtained the eigenvalues and their corresponding eigenvectors in the space and time domains for the above-mentioned data matrix. A comparative analysis between its spatial-temporal distribution and the China Geomagnetic Model (CGM) is made, and its physical meaning is studied. The research shows that the these observational data contain rich information of the internal and external geomagnetic source fields. The first and the second eigenvalues of the geomagnetic field components F, D and I, and the temporal variations of the geomagnetic main field described by the first and the second eigenvalues of the corresponding spatial-temporal domains coincide fairly well with the CGM.