The interpolation-iteration method for potential field continuation from undulating surface to plane
位场曲化平的插值-迭代法

The interpolation-iteration procedure of downward continuation from the undulating surface B to the horizontal plane A that below the lowest point of B is:(1) choose the initial potential field value at each point on the plane A as the observed one on the surface B at the point with the same horizontal coordinates;(2) intersect the surface B with several planes and obtain the field values on these planes by upward continuing the fields on A using the FFT technique,then the fields on the surface B can be interpolated from the fields on these planes;(3) the new field values on A are then obtained by adding the initial values and the weighted difference between the observed and the calculated field values on B;(4) repeat steps(2) and(3) until the difference becomes negligible.The interpolation-iterative continuation method possesses a higher computation speed and can stably downward continue data to a much deeper depth than using standard FFT techniques,up a depth equal to more than 10 times the grid interval.A test example for real survey data is given.