Abstract
Equations for the three-dimensional Shuman filter and its response function are presented. The filter heavily dampens even fairly long waves, but this can be alleviated somewhat by a second amplifying pass (tandem filter).
Due to the number of points (27) needed to filter the data, irregular boundaries and missing data can be a problem. The effects of one possible solution (reverting to three one-dimensional filters) is shown. Under some instances it is preferable to make only one pass to prevent propagation of boundary discontinuities.
