Sampling theory for asynoptic satellite observations. Part I: space-time spectra, resolution, and aliasing.

The information content of asynoptic satellite data is evaluated for nadir sonde and limb scan observations. Orbital sampling patterns are shown to uniquely determine the space-time spectrum, within well-defined sampling limitations. The latter turn out to be a hybrid of wavenumber and frequency in the same manner that the observations are a mixture of space and time. Space-time spectra thus computed are correct throughout the allowed region of wavenumber and frequency. Complexities such as orbital tilt and day-to-day drift of the nodes, are completely accounted for. -from Author