Bio-optical characterization of the water masses off the Svalbard Islands by laser-induced fluorescence

Arctic Ocean is probably the water body more affected by global warming. In the framework of a collaboration with the Institute of Oceanology of the Polish Academy of Sciences, the Laser Applications Section of ENEA deployed its laser-induced fluorescence sensors CASPER (laser spectrofluorometer), ELF and POLI (lidar fluorosensors) on-board the research vessel Oceania during three oceanographic campaigns off the Svalbard Islands in 2006, 2007 and 2008. While CASPER analyzed water samples collected at different depths, ELF and POLI sounded remotely the water surface operating H24. As a result, spectrofluorometer and lidar provided a spatio-temporal picture of chromophoric dissolved organic matter and algal pigments in a wide oceanic region. That information can be used for cal/val of ocean color satellite radiometers and, together with the temperature, salinity and water speed profiles measured by Polish researchers, can improve our understanding of the biogeochemical cycles taking place in the oceanic stream east of the Svalbard Islands.
CASPER (Compact and Advanced laser SPEctrometer for RIADE) is a laser spectrofluorometer. It has been patented and has been awarded the “Research and Innovation Prize 2005” by Business Innovation Center Latium. CASPER is based on double filtration (30 μm and 0.22 μm) and double excitation (frequency quadrupled Nd:YAG laser emitting at 266 nm and diode laser emitting at 405 nm) in order to detect both dissolved and particulate components of natural waters.
The main parts of a lidar fluorosensor are a frequency tripled Nd:YAG and a telescope detecting Raman scattering by water, laser-induced fluorescence by CDOM and algal pigments (chl-a, phycoerythrin and phycocyanin). ELF (ENEA Lidar Fluorosensor) participated to oceanographic campaigns in the Mediterranean Sea, Indian Ocean, Pacific Ocean and Southern Ocean. POLI (POrtable LIdar) is the natural evolution of ELF. All the subsystems, i.e. laser source, collecting telescope, detection optics and acquisition electronics (patented) are completely new and allowed the miniaturization of the apparatus now contained in a fly case of 0.7×0.7×0.8 m3.