2005.0年代中国地区地磁场及其长期变化球冠谐和分析

摘要

国家地磁图作为描述一个国家领域内地磁场空间分布的基础科技产品,其选用的模型计算方法应准确合理地反映标准年代上地磁场空间分布及未来5年的地磁场长期变化趋势.本文应用球冠谐和(SCH)方法,对中国地区1119个野外地磁测点和36个地磁台的观测数据进行了计算,获得了2005.0标准地磁年代中国地区地磁正常场及其异常场空间分布,建立了2005～2010年中国地区地磁场长期变化球冠谐和模型.结果表明,IGRF描述的中国地区地磁场偏差幅度约为5'(D、I)或100 nT(F),由于新的、空间分辨率更高的地磁测量数据参与计算,球冠谐和方法描述的2005.0地磁图能较IGRF更细致地描述地磁场的空间分布,具备稳定运用在中国地磁图的编制出版工作中的能力.%As a basic technological product describing the geomagnetic spatial distribution, the national geomagnetic chart should choose appropriate method to truly describe the geomagnetic field on standard epoch and its variation for coming 5 years. We used the Spherical Cap Harmonic (SCH) method to calculate the geomagnetic data at 1119 sites and 36 observatories in China on 2005.0 epoch, and obtained the normal and abnormal geomagnetic spatial structure in China and built an SCH model for geomagnetic secular variation in China for 2005～2010 epoch. The results have showed that the error of geomagnetic field by IGRF could be 5′for declination and inclination and 100 nT for total intensity. By using better resolution and newer geomagnetic data, the geomagnetic chart on 2005.0 epoch using SCH method should be better to describe the spatial structure of geomagnetic field. This method should be used in compiling Geomagnetic Chart for China stably.