空间域和频率域平面位场延拓影响因素和稳定性分析

位场延拓是重、磁位场数据处理的重要方法之一,高精度的位场延拓结果对后续的数据处理和解释尤为重要。笔者从平面位场延拓的基本公式出发,分析了空间域和频率域位场延拓结果精度的影响因素以及稳定性。通过理论模型测试比较了这些影响因素(场源体顶面埋深、剖面长度、扩边方法、窗口大小、点距和延拓高度)在空间域和频率域进行位场延拓时的异同性。经过测试表明,点距和延拓高度对延拓结果的影响最大,其次是剖面长度、扩边方法以及窗口大小,场源体的顶面埋深影响最小。随着顶面埋深的增大,会使延拓结果的精度降低;增大剖面长度和进行扩边会提高位场延拓结果的精度;选择合适滑动窗口可以提高计算效率,窗口越大延拓结果精度越高,窗口半径一般选择20倍延拓高度。空间域和频率域中位场延拓结果精度相当,但在空间域中,当延拓高度小于1倍点距时,延拓结果误差很大,此时需要用插值方法加密点距。

Influence factors and stability analysis of plane potential field continuation in space and frequency domains

Potential field continuation is one of the important methods of gravity and magnetic potential field data processing,and obtaining high-precision continuation results is particularly important for subsequent data processing and interpretation. Starting with the basic formula of plane potential field continuation,the authors analyzed the factors and the stability that affect the accuracy of continuation results in space and frequency domains. Using the theory model,the authors investigated the buried depth of the top surface of the field source,the length of the section,the method of edge enlargement,the size of the window,the dot pitch and the continuation height,and compared the different influences of these factors in space domain and frequency domain. The theory model test shows that the dot pitch and continuation height have the greatest influence on the continuation results,followed by the section length,the method of edge enlargement and the size of window,with the top surface of the field source exhibiting minimal influence. With the increase of the top surface’s depth,the continuation results accuracy is reduced. Increasing and expanding the length of the section will improve the accuracy of the field continuation results. Selecting the appropriate sliding window can improve the calculation efficiency,with the increasing window radius,the accuracy of the field continuation results is improved,and it can generally be chosen as 20 times of the continuation distance. The accuracy of the field continuation results have similarity in space domain and frequency domain;nevertheless,in space domain,the continuation error is very large when the continuation distance is less than 1 time of the dot pitch,so it needs to encrypt the dot pitch by using the interpolation method in this situation.