Open AccessAnalysis of variation in geomagnetic field of Chinese mainland based on comprehensive model CM4
Author(s) -
Yutong Feng,
Zhenchang An,
Fei Mao,
Han Sun
Publication year - 2010
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.59.8941
Subject(s) - earth's magnetic field , amplitude , field (mathematics) , longitude , physics , geodesy , variation (astronomy) , magnetic field , intensity (physics) , latitude , geology , astrophysics , mathematics , optics , quantum mechanics , pure mathematics
The fourth generation of comprehensive model of geomagnetic field CM4 is a numerical model in which earths magnetic field can completely be divided into internal and external parts. In this paper we have calculated and plotted the grid values of internal and external fields of Chinese mainland in every 10 a from 1960 to 2000 by combining CM4 with Taylor polynomial model based on all survey data during 1960—2000, and made more efforts to analyze the whole distribution of crustal anomaly field. Results show that internal field value of northern component X decreased with time. The amplitude was about 750 nT in the period from 1960 to 2000, the trend of external field variation increased in 1960, then gradually decreased about 32 nT until 2000. The internal field value of eastern component Y decreased first, then continuously increased, and its intensities decreased about 40 nT from 1960 to 2000. The trend of external field variation was increased, decreased and increased as time went on, and the external field increased up to about 3.8 nT since 1960. The internal field value of vertical component Z was similar to that of Y, its intensities totally increased about 600 nT. The trend of external field variation decreased and then increased with time, amplitude of which was about 4.6 nT. As for anomalous field, the distributions of components X and Z, total intensity F, and horizontal component H were all negative, the intensities of X and H decreased with longitude while those of Z and F increased. The distributions of Y and declination D were very similar and both of them had positive values in west-central region of China. Their intensities decreased with longitude. The distribution of inclination I was mainly negative, and its intensity increased with longitude.