Hayashi, Y., 1983: Modified methods of estimating space-time spectra from polar-orbiting satellite data Part II: The wavenumber transform method. Journal of the Meteorological Society of Japan, 61 (2), 263-268.

Abstract: In order to estimate space-time spectra correctly from uneven twice-daily data sampled by a polar-orbiting satellite, the wavenumber transform method (Hayashi, 1980) is modified by the use of a nonorthogonal Fourier inversion. The space-time spectra are obtained from the time-Fourier coefficients of the space-Fourier transforms of the asynoptic field with respect to its frequency-shifted wavenumber. Since this method requires the spatial interpolation of asynoptic data, it is effective only for ultralong waves. The wavenumber-frequency aliasing characteristics are examined and the computer code is exemplified.