利用IGRF模型计算全张量地磁梯度

The calculation method of full tensor geomagnetic gradient based on IGRF model

国际地磁参考场(IGRF)是一种描述地球主磁场的国际通用模型。目前利用该模型能够计算任意点位的地磁七要素,但随着航空全张量磁测技术的发展,对地球主磁场的全张量磁梯度数据有着迫切的需求。笔者梳理了IGRF模型的计算原理并进一步推导出球谐展开的全张量磁梯度表达式,实现了任意给定点位地磁场七要素和全张量的计算,并用地磁七要素与美国国家海洋和大气管理局(NOAA)网站计算数据进行对照,结果准确可靠。绘制了某地区地磁场的全张量磁梯度等值线图,结果满足Laplace方程,为航空全张量磁梯度测量中选择学习飞行工区和飞行高度提供了理论依据。

The international geomagnetic reference field(IGRF)is a general international model for describing the earth s main magnetic field.At present,this model can be used to calculate the seven elements of geomagnetic field at any point.However,with the development of aeronautical full tensor magnetic measurement technology,there is an urgent need for full tensor geomagnetic gradient data.In this paper,the calculation principle of the IGRF model is summarized and the expression of the full tensor geomagnetic gradient with spherical harmonic expansion is derived.The calculation of the seven elements of geomagnetic field and the full tensor geomagnetic gradient at any given point is realized.Comparing with the calculated data from the website of the National Oceanic and Atmospheric Administration of the United States(NOAA),the results are accurate and reliable.The contour map of the full tensor geomagnetic field in a region is drawn,and the results were in accordance with the Laplace equation.It provides the theoretical basis for the selection of learning flight working area and flight height in the aeromagnetic survey.