Linear Filtering on the Surface of a Sphere.
Abstract
Although methods of filtering have been developed for representing on a planar surface the sub-grid scale process of diffusion in numerical modeling of the atmosphere, the proper form of filtering for a spherical domain remains to be selected. In this study, the characteristics of several different forms of a highly scale dependent low pass filter are examined and compared for the case where the filter is applied to a scalar field on the surface of a sphere. The phase and amplitude response functions of the various forms of the filter indicate that the simplest form, although it does not preserve area-weighted mean values, approaches most closely the criteria established for the ideal filter. This indication is verified by the test computations in which each form of the filter is applied up to 10,000 times to a noisy scalar field. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 29, 1979
- Accession Number
- ADA082386
Entities
People
- Ralph Shapiro
Organizations
- Air Force Research Laboratory