时空Kriging算法在区域地磁场插值中的应用及改进

Application and improvement of spatial temporal Kriging in geomagnetic field interpolation

本文以区域地磁场为应用背景,研究了时间域信息对地磁场插值效果的影响.用时空Kriging算法进行插值时,在时空Kriging变差函数的拟合过程中,将角度信息引入向量距离,定义了新的向量距离形式,提出了改进的时空Kriging算法,并对权重的选取进行讨论.对经度87.2°E—126.6°E,纬度19.0°N—49.6°N范围内的32个台站时均值地磁场数据进行插值实验.在添加了时间信息之后,插值结果在兼顾经度方向和纬度方向变化的同时,边值问题也得以缓解,明显优于传统方法.交叉验证结果表明,随着时间域信息和向量角度的加入,Kriging算法的性能得到改进,地磁场的插值精度依次提高.对比实验中,改进Kriging算法的精度最高、性能最稳定,MAE集中在1nT左右,MSE集中在[0,5]的范围内.

This paper utilized Spatial Temporal Kriging method to improve the interpolation of regional geomagnetic field,by taking time domain information into consideration.Direction information was added to the variogram function of Spatial Temporal Kriging.A new kind of vector distance was defined to improve the method,meanwhile,selection of the weight in vector distance was discussed.Interpolation of geomagnetic field data from 32 monitoring stations in the region of longitude 87.2°E—126.6°E,latitude 19.0°N—49.6°N illustrated that,the results of methods which made use of information in time domain were much better than the traditional ones.Changes of geomagnetic field along longitude direction and latitude direction were both expressed adequately,while the boundary effect decreased.Illustration of the cross validation of geomagnetic field data indicated that,with the addition of time domain information and vector direction,the performance of Kriging method was improved in sequence.The improved Spatial Temporal Kriging method had the most accurate and stable performance in contrast test,with MAE concentrated at 1nT,and MSE concentrated in the interval of[0,5].