Characteristics of the Secular Variation and Secular Acceleration Distributions of the Main Geomagnetic Field from the CHAMP Satellite

Abstract Using the new geomagnetic model POMME‐4.2S derived from the CHAMP satellite data, we have analyzed the characteristics of the distributions of seven secular variation components and three secular acceleration components , Ÿ , in China and the world. We also compared the differences of the distributions between the secular variation models POMME‐4.2S and CGRF‐SV (Chinese Geomagnetic Reference Field‐Secular Variation). The results suggest that the quadrupole plays the main role in the geomagnetic secular variation, and the octupole occupies the largest portion in the contribution to the secular acceleration. The decrease of global secular variation is much larger than its increase in 2004.0 A.D. in the background of a decreasing trend of the geomagnetic field. The secular acceleration changes more at middle and low latitudes than that at higher latitudes. Moreover, the negative and positive magnetic anomalies of Ÿ and components form several alternating areas along longitudes, and these two kinds of anomalies of component are nearly symmetrical to the equator. An evident relationship is present for the magnetic anomaly distributions of the three secular acceleration components , Ÿ , . That is, the foci of magnetic anomalies exist in the south and north, and Ÿ in the east and west sides of the foci of magnetic anomalies. The amounts of change of the secular variation and acceleration in China are small and their distributions are relatively uniform.