Profiling floats

IFREMER has developed, through industrial partnership with KANNAD (http://www.kannad.com) company, a free-drifting hydrographic profiler based on MARVOR technology and named PROVOR. As MARVOR, PROVOR is a self ballasted float. It has an important volume variation and can be used in a wide range of density gradient.

The last version, PROVOR CTS3, is now also a platform able to carry various sensors (dissolved oxygen, optical irradiance and transmittance).

ARVOR, which design has been performed by Ifremer, is a light and easy to deploy profiling float, fully Argo compatible.

PROVOR CTS3

the profiler executes identical programmed cycles of descent, drift at depth at a given pressure for a few days, descent to the start of profile depth, raising, Argos data transmission.
T (Temperature or CT (Conductivity, Temperature) measurements can be carried out during the descent and the drift. During the first descent, data are acquired in order to enable comparison with CTD cast.
the profiler is not located at depth. It is located only at the surface during the ARGOS data transmission phase.
the profiler is able to synchronize the beginning of the rising profile in order to get synoptic CTD profiles from floats which are not deployed at the same time in an area.
the number of cycles is higher than 220 cycles (2000 meters depth, drift 10 days, transmission of 92 and 18 points averaged acquired during profile and drift, CTD continuously pumping).

With CTD pump in switched mode, theorical autonomy is up to 270 cycles.
in the case of groundind during the descent, the profiler can stay where it is stranded, waiting for the start of the ascent, or stabilise a few meters (programmable) higher, drifting for the length of the cycle at another level and trying to reach the nominal drifting depth on the next cycle.
the CTD measurements are carried out every 10 seconds and the data are processed before transmission to reduce the amount of information and keep only some points (averaging into slices).
Provor is fan tail ready, able to be launched in all seas by removing a magnet. But mission parameters can also be modified by user before launching.
The float can be deployed from any vessel at low speed using only a rope and from a high speed vessel (20 knots tested) by using release kit and launching crate.

The characteristics of the sensors are:

	Pressure	Temperature	Salinity
Range	0 to 2000 dBar	-5°C to 35°C	0 to 40 PSU
Resolution	0.1 dBar	0.001°C	0.001 PSU
Accuracy	ą 1 dBar	ą 0.002°C	ą 0.003 PSU
Drift	<5 dBar / 5 years	0.002°C / 5 years	<0.01 PSU / 5 years

The CTS3 PLATFORM

PROVOR DO is fitted with a CTD sensor and a dissolved oxygen sensor (Aanderaa). Several floats are already cycling and sending data using the Argos system.

(results on http://www.coriolis.eu.org/)

Oxygen sensor

PROVCARBON is fitted with a CTD sensor, a dissolved oxygen sensor (Aanderaa).and a transmissometer (WET Labs). Data are transmitted using Iridium system.

(results on http://www.coriolis.eu.org/)

PROVBIO is a float with temperature, conductivity, optical irradiance and transmittance measurements (Iridium transmission).

PROVOR A: a float performing CTD measurement and using RAFOS, acoustic positioning during drift.

ARVOR

This new autonomous oceanographic profiling float has the same main characteristics and metrology than Provor. Lighter, cheaper, it is devoted to temperature and salinity measurements for Argo applications.

Its design has been performed by IFREMER and it is manufactured by KANNAD.

Arvor float can perform more than 200 cycles from 2000 meters depth to the surface (CTD pump in continuous mode)

Deployable by only one person, with wireless connectivity using Bluetooth.