Ocean Science www.ocean-sci.net 1812-0784 1812-0792 3 1 2007 10.5194/os-3-117-2007 http://www.ocean-sci.net/3/117/2007/ http://www.ocean-sci.net/3/117/2007/os-3-117-2007.html http://www.ocean-sci.net/3/117/2007/os-3-117-2007.pdf 117 128 2007-02-23 M3A system (2000–2005) – operation and maintenance G. Petihakis pet@her.hcmr.gr P. Drakopoulos C. Nittis V. Zervakis C. Christodoulou C. Tziavos Institute of Oceanography, Hellenic Center for Marine Research, P.O. BOX 2214, Iraklion-Crete, GR 71003, Greece Optical Instruments Laboratory, Department of Optics, Technological Institute of Athens, Greece Department of Marine Science, University of the Aegean, Mytilene, Greece During the pilot phase of the Mediterranean Forecasting System (MFSPP) (2000 2003), a prototype observing system (Mediterranean Moored Multi-sensor Array – M3A) was designed, developed and operated in the Cretan Sea for continuous oceanographic measurements in real time. The main problems encountered were associated with biofouling, underwater and aerial communication and with the design of the surface buoy. In the second phase of the MFS project named Mediterranean Forecasting System Towards Environmental Predictions (MFSTEP) (2003–2005), the aim was to solve those problems and to consolidate the M3A. For the minimisation of biofouling a pilot field study was performed and the techniques of bromine solution and copper shielding were evaluated. Additionally, the oligotrophy of the Aegean Sea dictated the need to ignore factory calibrations and to perform site-specific laboratory calibrations of the sensors. This procedure was proved necessary and produced calibration coefficients that gave results comparable to the measurements obtained with the laboratory analysis method. During the approximately five years of operation, there were 13 scheduled and 15 emergency visits, with a total duration of 65 days. 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