On the Uniqueness of Space-Time Spectra and Synoptic Maps Derived from Polar-Orbiting Satellite Data

摘要

Two methods for deriving space-time spectra from asynoptic satellite data, the frequency transform method (Hayashi, 1983a) and the asynoptic space-time transform method (Salby, 1982a) are shown to be equivalent. That is they give identical spectra and have identical aliasing characteristics. When asynoptic sampling conditions are satisfied, this linear transformation is unique and recovers the correct spectrum over wavenumber and frequency for a satellite observed field. Moreover the synoptic mapping of asynoptic data, as implied by this operation, is the only linear transformation capable of extracting the true synoptic behavior from asynoptic measurements. Other procedures used to derive synoptic behavior must reduce to this transformation if they are to consistently recover the correct structure and evolution.