Linear filtering on the surface of a sphere /
Ralph Shapiro.

Description

Main Author

Shapiro, Ralph.

Related Names

U.S. Air Force Geophysics Laboratory.

Language(s)

English

Published

Hanscom AFB, Massachusetts : Air Force Geophysics Laboratory, Air Force Systems Command, United States Air Force, 1979.

Subjects

Sphere.
Numerical weather forecasting.
Filters (Mathematics)
Digital filters (Mathematics)
Diffusion.
Atmospheric models.
Diffusion.
Atmospheric models.
Sphere.
Digital filters (Mathematics)
Filters (Mathematics)
Numerical weather forecasting.

Summary

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).

Note

Research supported by the Air Force Geophysics Laboratory, Air Force Systems Command, United States Air Force, Hanscom AFB, Massachusetts.
Meteorology Division Project 2310.
ADA082386 (from http://www.dtic.mil).
"29 October 1979."

Physical Description

32 pages : illustrations ; 28 cm.

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