Cloud detection over sea surface by use of autocorrelation functions of upwelling infrared spectra in the 800-900-cm(-1) window region

A new algorithm for cloud detection over sea surface has been developed tha t makes use of autocorrelation and cross correlation between a real spectru m and either a synthetic or a laboratory spectrum. The scheme is intended f or high-spectral-resolution satelliteborne infrared sensors that will measu re the Earth's entire emission spectrum rather than the upwelling radiance in a few channels. A new index is defined with which one can determine quan titatively the degree of homogeneity of two spectra in the 800-900-cm(-1) ( 11.11-12.5 mu m) window region. The index makes use of only the observed sp ectrum along with a reference synthetic spectrum and, therefore, may form t he basis for an operational stand-alone cloud-detection algorithm for next- generation high-spectral-resolution infrared sensors. Application both to s ynthetic spectra obtained in simulation and to sea-surface real spectra rec orded through the interferometric monitor for greenhouse gases is considere d. (C) 2000 Optical Society of America OCIS codes: 010.0010, 010.1290, 010. 3920, 280.0280.