An AVIRIS image was obtained for Mono Lake California on 26 May 1989 a day with excellent visibility. Aospherically-corrected reflectance spectra derived from the image indicate a spectral signature for chlorophyll a the dominant photosynthetic pigment in the phytoplankton of the lake. Chlorophyll a concentrations in the lake were about 22 mg m3 and the upwelling radiance was low with a peak reflectance at about 570 nm of about 5. Coherent noise appeared in the image as regular variations of 0. 1 to 0. 2 p. W cm2 t1 oriented diagonally to the flight line. A simple ratio of two spectral bands removed the conspicuous undulations but modifications of the shielding within the instrument are needed to improve the signal especially over dark targets such as lakes. 1.