Technological developments Ifremer/Coriolis, AWI EURO-ARGO/ESFRI

ARVOR float Arvor : new float dedicated to CTD measurements for Argo Deployment facilitated (smaller, lighter weight <20 kg) and to reduce manufacturing costs. 10 instruments manufactured in May + intensive tests done in 2008 2 Arvor were successfully deployed in southern ocean; they are cycling every 2 days to assess their performance and have performed 5 cycles; 8 more will be deployed in Atlantic this summer

Transmission through Bi-directional communication Iridium transmission implemented on ProvCarbon and ProvBio which are Argo floats (Provor) fitted with extra optical sensors. 2 ProvCarbon have been deployed in February 2008 and have performed more than 50 cycles today ( 5 days period) Surface times could be reduced to 30 minutes; the surface time is allocated to increasing the buoyancy of the float to sufficiently rise the antenna (about 5 min), the iridium transmission (around 5 min), and finally to reduce buoyancy.

Transmission through Bi-directional communication 12 ProvBio have been manufactured and most of them have been deployed (http://www.obs-vlfr.fr/OAO/). Iridium/GPS antenna developed and tested for 2000 dbar operations. Iridium satellite downlink capability successfully tested Development of an Arvor equipped with an Iridium antenna Use of ARGOS-3 transmission ? new modem PMT from CLS Argos tested Implementation on Arvor and deployment in 2009 4

PROVOR-DO Provor + dissolved oxygen sensor (optode) Change the sensor position: top  bottom Optode closer to the CTD No temperature bias induced by the float Calibration possibilities in moist air Correction of two bugs in the software Two floats are currently tested Lifetime of float: Extra power for sensor ~8% of total provor energy (for optode), lifetime is maintained beyond 3 years. cost of optode sensor: ~5900€. PROVOR-DO New Aanderaa optode under tests: new foil for better response time, less response time temperature probe near the foil Existing technology on PROVORDO: 3830 Aanderaa optode ·        Temp The absolute sensor accuracy is today it is ±5 % or ±8 µM (whichever is greater). Factory settings and calibration is sometimes erroneous. ·        90 % response time is today around 40 s, that is too much. The position on the float is not ideal (lower end cap) when profiling on the ascent and atmospheric measurements are not possible when the float is “parked” at the surface. It could also be a difficulty to compare measurements with CTD, eg. in presence of high temperature gradients .   Measurement is done every CTD sample (10s). The optode is switched on during 2s, and off 8s. Extra power for optode lead to consume ~8% of total float energy, so lifetime capabilities of Provor float could be maintained beyond 3 years. Temp The cost of an optode is around 4000€.

New developments CTD Improvements: less energy consuming for new 2009 model (180mW vs 300mW today). Investigation for deep measurements Higher pressure operation to 3500 dbars: available with titanium pump impeller housing rather than plastic, and Druck Pressure sensor (about same price than 2000 dbars model). 7000 dbars expected in 2009. Further sensor investigations on the CTD accuracy CTD Seabird seems to give good data today Metrology on Provor: >30% of total energy o float because of continuous CTD pumping <10% if pump was switched on/off Doug Bennett a écrit : Dear Serge, Thank you for your inquiry, and I apologize for the delay in responding .  The SBE 41 and 41CP both have a pump.  The SBE 41 was the first generation PALACE CTD. It was designed to make discrete point measurements (about 70) during the float ascent to create a profile.  Each sample is made in response to a command or pulse, and the pump runs for a few seconds (e.g. 3-8) before the T, C & P measurements are made.  Specific operation can vary depending on firmware written for specific applications. With the growing use of Iridium for data telemetry,  it became practical to transmit larger amounts of data and thereby increase CTD profile accuracy and resolution. Accordingly, we introduced the SBE 41CP ("Continuous Profiler").  The 41CP pumps continuously and samples at 1Hz.  Upon surfacing, data can be averaged into depth bins, or the full profile can be sent. Pumping continuously and sampling at 1 Hz provides the constant flow condition necessary to minimize thermal mass errors in the conductivity cell, which can be large in the thermocline. (see attached application note, page 3, para. II & III for reference).  Even with continuous sampling and pumping, small residual cell thermal mass errors are possible. Transmitting the full 1Hz profile enables corrections to be made later that cannot be made if  data are bin averaged or spot sampled. There are no electronic warm up issues. Webb uses the SBE 41 for most  of their APEX floats, but increasingly uses some SBE 41CPs. However, it is our understanding that the APEX/41CP floats transmit bin-averaged data. You can conserve power on long profiles by spot sampling below 1000 meters (or other threshold) and sampling continuously above the threshold. The continuous data above a threshold pressure can optionally be averaged into/reported in pressure bins) and spot samples can be commanded every 50 dbar (for example) below the threshold pressure. Dr. Steve Riser / Dana Swift at Univ. Washington use APEX /41CP in this way, running the pump for 20 seconds (2 dbars of ascent) before each spot sample, then leaving the pump off for 48 dbars. Here is a link to one of Dana's irridium-communications floats with the spot and continuous sample scheme.    http://flux.ocean.washington.edu/argo/homographs/TP/5056/5056.064.html I am pleased to inform you that we have recently made significant efficiency gains in the SBE 41CP pump and electronics, and we can offer 7000 meter depth capability.  The current 41CP (as used on Provor consumes approx. 300 milliwatts.  Our new SBE 41CP will consume less than 180 milliwatts (possibly only 165) .  Production of  the new  41CP  will begin around the end of 2008. To achieve depth capability greater than  2000 dbar, we use a titanium pump impeller housing, rather than plastic.  This part is the same as used on SBE 49 FastCAT (http://www.seabird.com/products/spec_sheets/49data.htm).  The titanium impeller housing adds about 255 grams to the weight of the standard SBE 41CP (not including Provor end cap or chassis hardware). At this time, we can offer a Druck pressure sensor with 3500 dbar range. In 2009 we expect to have a 7000 dbar  pressure sensor. Best regards, Doug Dear Serge, The 41CP with 3500 meters depth capability (3500 dbar Druck pressure sensor and titanium impeller housing) is $5,185 (not including end cap) for quantity less than 10. The standard 2000 meter version is currently $5000 USD for quantity less than 10. I would think that a 3500 meter version of the current Provor end cap could be made for the same cost (same raw material, machining, anodizing costs.  We can confirm with a quotation if you send us a drawing. Best regards, Doug

Ice sensing Initially, Argo was intended to observe deep ice-free ocean in real time, but the ice-resilience of floats has been increased. Nemo (optimare) is fitted with 3 main features: Ice Sensing Algorithm (ISA) to improve endurance in ice-covered seas, Interim Storage of aborted profile data in presence of ice at surface, Subsurface RAFOS navigation to locate profile/ float under the sea ice. Development of a new ISA algorithm for deployment in the Arctic A non Argo model of Provor (NKE) exists for ice thickness assessment. It uses the subsurface RAFOS navigation (Provor-A) coupled with an upward looking acoustic sounder.

Under-ice floats in Antarctica : 5 years of experience