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Sensore LIDAR fluorosensore

Referente: Dr. Luca Fiorani
luca.fiorani@enea.it

Fig. 1. ELF during the AREX oceanographic campaign of 2007 in the Arctic Ocean.

The main parts of a lidar fluorosensor are a frequency tripled Nd:YAG laser and a telescope detecting Raman scattering by water, laser-induced fluorescence by CDOM (chromophoric dissolved organic matter) and algal pigments (chlorophyll-a, phycoerythrin and phycocyanin). ELF (ENEA Lidar Fluorosensor) is a technological product of PNRA (Italian Antarctic research program) and participated to oceanographic campaigns in the Mediterranean Sea, Arctic Ocean, Indian Ocean, Pacific Ocean and Southern Ocean (Fig. 1). Thanks to narrowband filtering and electronic gating, laser-induced fluorescence signals do not need corrections for radiometric and spectral characteristics of solar irradiance and surface reflectance. Furthermore, due to the short distance from the target, atmospheric effects are negligible. This explains why ELF data can be regarded as sea truth and have been provided to WOOD (Worldwide Ocean Optics Database) of ONR (Office of Naval Research) and SeaBASS (SeaWiFS Bio-optical Archive and Storage System) of NASA (National Aeronautics and Space Administration). Moreover, ELF data have been used for the calibration of the bio-optical algorithms of the ocean color satellite radiometers MERIS, MODIS and SeaWiFS that determine the chlorophyll-a concentration from the blue-to-green ratio of the sunlight backscattered by the sea surface. POLI (POrtable LIdar) is the natural evolution of ELF (Fig. 2). 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 0.70.70.8 m3 (Fig. 3), according to the guidelines of the Italian project MIAO (microsystems for hostile environments).

Fig 2. POLI during the laboratory assembly and tests.


Fig 3. POLI installed on the R/V Urania's mezzanine deck during the PRIMI oceanographic campaign of 2009 in the Mediterranean Sea.


Fig. 4. Surface chlorophyll-a concentration measured by ELF during the Italy - New Zealand transect (13 November - 18 December 2001) of the MIPOT oceanographic campaign.


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References:

  • R. Barbini, F. Colao, R. Fantoni, L. Fiorani, and A. Palucci, "Remote sensing of the Southern Ocean: techniques and results," Journal of Optoelectronics and Advanced Materials 3, 817-830 (2001);
  • R. Barbini, F. Colao, R. Fantoni, L. Fiorani, and A. Palucci, "2003, Lidar fluorosensor calibration of the SeaWiFS chlorophyll algorithm in the Ross Sea," International Journal of Remote Sensing 24, 3205-3218 (2003);
  • F. Colao, R. Fantoni, L. Fiorani, A. Palucci and M. Sighicelli, "Laser-induced fluorescence measurement of sea water bio-optical parameters during the SESAME campaign," in Barale V., Gower J.F.R., Alberotanza L., eds., Proceedings "Oceans from Space" Venice 2010, Joint Research Centre of the European Commission, Ispra (2010);
  • F. Colao, R. Fantoni, L. Fiorani, I. Menicucci, M. Nuvoli, A. Palucci and G. Terranova, "Lidar identification of oil spills during the PRIMI cruise," in Barale V., Gower J.F.R., Alberotanza L., eds., Proceedings "Oceans from Space" Venice 2010, Joint Research Centre of the European Commission, Ispra (2010).
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