This article presents the results of analyzing data which were collected in the sea with a structured illumination/fluorescence imaging system. The system employs all lines of an argon ion laser to create a 2D slice illumination pattern in the blue-green. A sensitive CCD camera was used to measure the fluorescence emission resulting from this stimulation. Under our assumptions, these images are proportional to chlorophyll-a concentration. Inspection of the data reveals a large degree of small scale patchiness with characteristic distances as small as centimeters. In many of the images, the chlorophyll concentration is seen to change by an order of magnitude over several centimeters. Patchiness was characterized via the use of spatial spectral estimation techniques. Preliminary results show that the data follow a -5/3 slope at high wave number, consistent with the hypothesis that the patches were formed by turbulent stirring of larger scale gradients of phytoplankton. In addition, repeated vertical profiles demonstrated that the larger scales were extremely constant, even in the presence of this small scale variability. The technique has provided an original data set with important new information about the small scale structure of pigment in the ocean.
Jules S. Jaffe,
P. J. S. Franks,
"Small-scale optical structure measured via images of fluorescence emission", Proc. SPIE 2963, Ocean Optics XIII, (6 February 1997); doi: 10.1117/12.266455; https://doi.org/10.1117/12.266455