中文摘要：

因延拓深度有限,现有的位场向下延拓方法不能从航磁资料向下延拓出海面的磁场.位场大深度向下延拓方法——迭代法,可以从航磁资料向下延拓出海面的磁场,得出与航磁同比例尺的海面磁力图,可大大提高海洋磁测成果的综合利用率.介绍了迭代法位场延拓原理.用迭代法对实际资料进行了处理,讨论了误差产生的原因.对比了迭代法与快速傅立叶变换法（FFT）在位场向下延拓中的效果,迭代法显著优于FFT法.

英文摘要：

The existing methods of downward continuation of potential fields connot be used to continue the aeromagnetic data to the sea level because of the limited continuation depth. An iteration method for downward continuation of potential fields with a larger continuation depth has been developed, which can continue the aeromagnetic data to the sea level and get the sea-magnetic chart with the same scale as the aeromagnetic data. This downward continuation method will greatly raise the efficiency of seamagnetic investigation. The principle of the iteration method is presented and a real case with a discussion on error of continuation is given. The effects of downward continuation of potential fields are compared using the iteration method and the fast Fourier transform（FFT） respectively, the former is much better than the latter.