中国地震局地球物理研究所与蒙古科学院天文与地球物理研究中心于2011—2012年合作开展了蒙古119个野外地磁测点的测量工作．本文利用蒙古119个测点准确可靠的地磁数据，分别加上9组边界点 EMM2010模型计算值，得到了蒙古2010．0年代地磁异常场的9个球冠谐和模型；给出了地磁异常场北向分量ΔX 、东向分量ΔY 和垂向分量ΔZ 的等值线分布图，并比较分析了这9个模型的异同；同时计算了119个测点的地磁测量值与模型计算值之差的均方根误差σ，以σ为指标来表征这9个模型的精度，由此定量评价了边界点选取对模型精度的影响．结果表明，适当引入边界点能够提高模型精度，而远离测区3°—5°的均匀边界点也能起到改善模型精度的作用．因此在实际建模时，应当在计算区域边界引入适当的边界点，以改善地磁模型的精度．%During the period of 2011 to 2012,Institute of Geophysics,China Earthquake Administration has partnered with Research Center of Astronomy and Geophysics of Mongolian Academy of Sciences,and accomplished geomag-netic survey (total intensity F ,magnetic declination D ,magnetic inclination I ) of 119 stations in Mongolia.We calculate nine spherical cap harmonic models of geomagnetic anomaly field in Mongolia of 2010.0 epoch by using the accurate geomagnetic data of 119 stations and adding selected boundary point values of nine groups calculated by EMM2010 model respectively.And then we give the contour maps of north component ΔX ,east component ΔY and vertical compo-nent ΔZ ,by which the nine models are compared.Root mean square (RMS)error of the difference between geomagnetic survey values and calculated values at 119 survey stations is calculated to represent the accuracy of the nine models so as to evaluate quantitatively the influence of boundary points selection on the accuracy of the models.The RMS analysis results indicate that,besides appro-priate boundary points selection can improve model accuracy,the boundary points away from the measuring region 3°—5°can also improve model accuracy. Therefore,the appropriate boundary points should be introduced to improve accuracy of geomagnetic model in establishing model.
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