ATMOS Example Interferogram The files in this directory ftp://thunder.jpl.nasa.gov/atmos/interf are a sample ATMOS interferogram and the power spectra produced from it. The data is from the Atlas-3 mission and is taken with ATMOS optical filter 12 (600 - 1400 cm-1). This is a numerical example of the Fast Fourier transform process as implemented in ATMOS Data processing software. The interferogram file contains 794,448 points stored as a vector of floating point numbers (32 bit real). NOTE: Data are stored as pure binary, not unformatted FORTRAN format!!! The spectra have not been truncated but contain the entire alias (0-3900 cm-1). The spectra files each contain 517,716 points stored as a vector of scaled 16 bit integers (high byte-low byte). Spectral values have been normalized to 30,000. The difference between the spectrum.corr and the spectrum.uncorr files is the nonlinearity correction applied when producing the power spectrum. The spectrum.uncorr file is an uncorrected power spectrum. The spectrum.corr has a -2.0e-6 nonlinearity correction factor applied. For more information on the nonlinearity correction see M. C. Abrams, G. C. Toon, and R. A. Schindler, "Practical example of the correction of Fourier-transform spectra for detector nonlinearity", Appl. Opt. 33, 6307-6314 (1994). Go back to the previous page. File modified by: J. Foster 6-17-96 / Links updated by Bill Irion 3/19/01