PROVOR: a hydrographic profiler based on MARVOR technology

IFREMER has developed, through industrial partnership with the TEKELEC/MARTEC company, a Lagrangian subsurface float, named MARVOR. While drifting at depth, MARVOR can be located using the RAFOS technique and comes up to the surface at regular intervals to transmit via ARGOS all gathered data, including pressure, temperature, time of arrival of acoustic signals. Most of the floats are programmed to drift at depth for two or three months and spend two or three days at the surface but some others are deployed inside eddies and surface every month. As MARVOR is self-ballasted, operating pressure can be decided just before deployment. These floats were designed for an operational life of 3 years and about fifty cycles. The first serial equipments were launched at the beginning of 1994, so some of them have already been operating for more than 4 years. This paper presents an evaluation of the global behaviour at sea of the first hundred floats and gives some statistic informations about life duration, causes of failure and drifts of sensors. Moreover, it shows the modifications which have been done to ensure a higher reliability or compensate some aging phenomenas. At least, it presents the characteristics of the PROVOR float which is a hydrographic profiler, based on MARVOR technology.