Fluorescence of phytoplankton

One of the first photos taken by Envisat, ESA's Earth observation satellite on 22 March 2002.
MERIS has the capability to remote sense phytoplankton by observing their fluorescence. Phytoplankton pigments absorb light in short-wavelength radiation (blue) and partially reemit it at the fluorescence wavelength. This technique is of very high interest in coastal waters where turbidity makes chlorophyll retrieval more difficult than in the open ocean. This image is the very first attempt done to verify the capability of MERIS to detect fluorescence from space. It will take several months of intense field measurements to compare the satellite data to in situ measurements, to perfectly characterize the instrument and make sure high quality data are delivered to MERIS users. The first results are already fascinating and surprisingly rapid.