地磁测量和地磁场建模是地磁学研究和应用的重要内容之一,构建全球和局部地区地磁场模型的物理依据是位场理论,观测依据是地面、海洋、航空、气球和卫星的磁场探测资料.地磁场建模涉及两个问题,即如何选取合适的基函数和怎样实现最佳的拟合.全球建模的经典方法是球谐分析(简记为SHA),它无论在理论上,还是在数值计算上均已非常成熟.与之相比,局部区域磁场建模的方法虽然很多,但是它们的数学理论还不完善,计算技术尚待发展,有效性不断受到挑战,模型的物理解释也常常受到质疑.本文用比较分析的方法,探讨了全球建模的常规球谐分析(SHA)和局域建模的矩谐分析(RHA)、冠谐分析(SCHA)及修正冠谐分析(RSCHA)等方法在理论基础和数学处理中的差异,分析它们拟合磁测资料的优缺点,指出它们的局限性和适用场合.
Magnetic field modeling both in global scale and in limited region is one of the essential issues of magnetic survey and studies. Compared with Spherical Harmonic Analysis (SHA) commonly used in global modeling, the methods for regional modeling have less developed theory background, the fitting techniques in these methods are improving, their validity in applications are frequently challenged, and the physical explanations of the results are questioned. In this paper a comparative investigation is carried out to explore differences between the ordinary SHA (OSHA) for global modeling and the methods for regional modeling, such as Rectangular Harmonic analysis (RHA), Spherical Cap Harmonic Analysis (SCHA), and revised Spherical Cap Harmonic Analysis (R-SCHA), to analyze their advantages and drawbacks in fitting observed data, and to point out their limitations and applicability.