The Fast Computation Of The Geomagnetic Field Reference Model And The Study Of Parallel Speed Up Technology

As the basic geophysical field, geomagnetic field is widely used in seismic detection,exploration, autonomous navigation, attitude determination, space weather forecast and other fields. In recent years, with the continuous development of space magnetic measurement and aerospace magnetic measurement technology, scholars at home and abroad have studied the law of geomagnetic field with time and space, and a series of high-order and high-precision geomagnetic field reference models have been established. The high-order geomagnetic model needs high computational complexity, and how to realize the efficient calculation of the geomagnetic field model is the core problem of accelerating the application of high precision geomagnetic model in engineering practice.This paper studies from two aspects: geomagnetic model theory and physical processing,on the one hand, the related research of the rapid calculation of spherical harmonic function in geomagnetic field reference model is carried on; on the other hand, we use parallel processing technology to improve the multi-point calculation efficiency in the magnet-map.First, the generalized form of the solution is obtained from the geomagnetic model spherical harmonic function; and then the fast recursive algorithm of the Schmidt semi-orthogonal legendre function is studied ,The algorithm of calculating the forward column recursion, the forward row recursion, the cross-order recursion and the method of the abnormal spherical harmonic function are given in terms of different order and degree. Based on the existing mainstream geomagnetic model IGRF, WMM, MF7 and EMM2010 (including NGDC720), the computational efficiency of each algorithm is simulated and compared; Finally,the geomagnetic visualization software is designed based on the parallel acceleration technology to improve the calculation speed of the regional multi-point geomagnetic field vector and realize the fast drawing of regional geomagnetic map.The results show that the accuracy of the above calculation method is quite constant. With the increase of the order of the geomagnetic reference model, the computational efficiency of the abnormal spherical harmonic function is more obvious than that of other algorithms. It can be used for parallel computing, the calculation time of 360x360 point area of the main magnetic field is 2ms and the calculation time of 360x 360 point area of the geomagnetic anomaly field is 10ms, and it provides a solution for the rapid calculation and application of geomagnetic model in engineering.