The downward continuations are made by the iteration method and the FFT for a model and practical data, respectively.The effect of the iteration method is much better than the FFT.

• 本文用迭代法对模型数据和实际数据进行向下延拓，对比了迭代法与常规的FFT法在位场向下延拓中的效果，迭代法显著优于FFT法。