Cruise Plan for DIMES Deployment Cruise R/V Revelle

January-February 2008 46-day cruise, counting departure and arrival days

James R. Ledwell, Chief Scientist

Woods Hole Oceanographic Institution jledwell@whoi.edu, 508-289-3305

DRAFT, 17 April 2008

Objectives The objectives of the cruise are to: 1.) Deploy six RAFOS sound source moorings 2.) Perform an XBT/CTD survey prior to the tracer release 3.) Release up to 400 kg of tracer on an isopycnal surface at about 1500 m depth 4.) Deploy 75 RAFOS floats 5.) Deploy 5 shearmeter floats 6.) Deploy 6 EM-APEX floats 7.) Deploy approximately 6 Argo floats 8.) Sample the initial tracer distribution with a towed array of samplers A prospective cruise track is shown in Fig. 1. Clearance We do not anticipate needing clearance from foreign nations for this cruise. Sound Source Deployment The approximate positions of the six sound sources to be deployed are: Lat (S) Long (W) Depth (m) 56.0 86.0 5028 58.0 98.0 4800 56.0 110.0 4002 60.0 110.0 5043 60.0 86.0 5011 57.9 75.3 The first mooring in this list might be close to Chilean waters, but it can be moved. It is our intention to avoid the need for clearance for this cruise.

Jim Ledwell ! 4/23/08 1:40 PM

Jim Ledwell ! 4/18/08 11:48 AM

Jim Ledwell ! 4/18/08 11:48 AM

Jim Ledwell ! 4/18/08 11:49 AM

Comment: I have suggested this move to get out of Chilean waters. Kevin and Peter gave it the OK 4/23/08

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Deployment of the sound sources will require a mooring winch. If SIO can provide one then we will use it. Otherwise WHOI will ship one of its own. Figure 2 shows a sound source being deployed. Figure 3 shows a sample mooring diagram.

Fig. 1. Prospective cruise track. The northern leg would be done first, and the southern leg on the way back to Punta Arenas. The 6 dots along the track represent sound source moorings that must be deployed. The 2 dots near 62 W are sound sources to be deployed on a later cruise. The XBT profiles will be taken along the line at 105 W. The tracer release and tracer sampling will be performed roughly in the square at approximately 60 S, 105 W. The final position will be determined after the XBT line is occupied. All of the floats will be deployed along the XBT line or in the vicinity of the tracer deployment and sampling region.

Fig. 2. Sound source mooring deployment from R/V Seward Johnson

Fig. 3. Example of a Sound Source Mooring Configurtion CTD/XBT Line A line of 1830-meter (6000 ft) XBT's will be occupied prior to the tracer release at 105 W, between 63 S and 57 S.

Tracer Deployment The tracer is trifluoromethyl sulfur pentafluoride, CF3SF5. It will be stored as a liquid under pressure in approximately 8 high-pressure cylinders. It is a substance of low hazard to humans and marine life, though it is a powerful greenhouse gas. The vapor pressure at room temperature is about 3 atm (45 psi). The primer fluid for the tracer pumping system is Vertrel-XF (decafluoropentane, C5H2F10). We will bring approximately 50 liters of this substance. It is also a low hazard material. MSDS sheets for both compounds are attached. The tracer will be deployed with a tracer injection sled on a surface of constant potential density that is about 1500 m deep. The sled will be deployed at the starboard waist using the CTD winch and wire, and towed at a speed of about 1 knot with the wind usually just off the starboard bow, depending on waves and swell directions also. The sled is neutrally buoyant in water, though it weighs approximately 1500 lb in air. Hence, a depressor weight of 100 to 200 lb is needed to deploy it (Fig. 4). This depressor weight is lowered on a 50-m length of cable, which we call the auxiliary cable. This cable requires a second winch for deployment and requires its own wide-mouth block, usually placed near the CTD block. The mouth of the block must be wide enough to allow the coupling between the auxiliary cable and the bull line on the secondary winch to pass. When this coupling gets to the rail, the end of the auxiliary wire is attached to the termination of the CTD cable with shackles and a pear-ring, and the strain of the depressor weight is taken by the CTD winch. A 2.5-m towing bridle attached to the forward end of the sled is also coupled to the pear ring, and electrical connections are made to the CTD cable. At this point the sled is deployed over the rail with a crane and tag lines (Fig. 5). The CTD winch and boom must be operated in unison with the crane, since the towing bridle is connected to the CTD termination. When the sled is in the water the line to the crane is released with a quick-release hook. Then the sled can be lowered at a speed of about 20 m/min. Once the sled is safely below the surface (say 100 m), the CTD winch is turned over to automatic control from the lab. The automated system will bring the package to the target density surface, and once control parameters have been adjusted for following the surface properly, injection will commence. It will take about 16 hours to expel one load of tracer (about 40 kg). Our goal is to release nearly 400 kg of tracer. We have budgeted 2 weeks for the tracer deployment. The ship will travel approximately 30 km during the release of one streak, most likely towards the west, i.e. into the wind. We will attempt to confine the injection streaks to a region that is 50 x 50 km, in a coordinate system moving with the water at the level of the tracer. The mean motion of the water at the depth of the tracer (1500 m) will be estimated using satellite altimetry, the ships Doppler sounder, and the XBT/CTD data, all assimilated into a dynamical model.

Tracer sled launch and recovery will require a crane operator, a CTD winch operator and the ship’s Bosun. The science party can handle tag lines and make all interconnections between the sled and cables.

Fig. 4. Schematic of injection sled in the water.

Fig. 4. Injection sled deployment from the R/V Oceanus RAFOS Float Deployments The RAFOS floats will be a bit heavier than the standard glass tubes, about 30 lbs in air, and about 2.5 meters long, and can be deployed with the aid of a release system by two people from the science party. The timing and location of the deployments remain to be worked out, but in general the floats will be deployed in the vicinity of the tracer, and

during tracer injection and sampling, or during the XBT/CTD line prior to the tracer injection. Shearmeter Deployments The shearmeters are 7 meters long, and weigh about 160 lb in air. They are also deployed by hand, though the deployment method for the shearmeters is still being worked out. It is safe to assume that no less than 4 people from the science party will be required on deck and there is a possibility that a crane operator will also be needed. There is a test cruise in May 2009 on R/V R. G. Sproul which will work some of the procedures out. Five shearmeters will be deployed on this cruise, during the tracer injection. EM-APEX Float Deployments The EM-APEX floats will also be deployed by hand during the tracer release period. They are similar to Argo floats, described below, in size and weight. Argo Float Deployments The Argo floats are about 2 m long, including the antenna, and weigh 55 lbs in air. They will be deployed (by hand) at widespread locations during the cruise, since the standard grid spacing for deployment is about 330 km. Two of the Argo floats will be deployed with the tracer, however. Tracer Sampling About 4 days after the end of the tracer release, the tracer patch will be sampled with a towed array of samplers. The 4 days are required to set up the sampling and analysis gear, which must be kept sealed up during the injection to protect it from contamination during injection. Float releases and further XBT drops may be done during this period. The sampling array has a sampling sled at the bottom of the CTD cable (Fig. 6), with 10 to 12 integrating samplers (Fig. 7) hung on the wire above the sled, and 10 to 12 more samplers hung on an auxiliary cable below the sled. The sled is not neutrally buoyant like the injection sled, and is attached directly to the CTD termination. It weighs about 500 lbs in air. The integrating samplers are mounted on 5-liter Niskin bottles. As for the injection gear, a secondary winch is required to deploy the 50-m long auxiliary cable. The weight at the bottom of this cable will be 500 lbs to enable tow speeds up to 2 knots. The array will be towed from the starboard waist, as for the injection sled, and so the direction of tow will be constrained by wind and sea conditions. The tow speed will be approximately 1.5 knots, so that nearly 30 km will be covered during the 10 hours required for the integrating samplers to fill.

Aside from the CTD on the sled, there are two integrating samplers and a 50-chamber sampler. The chambers fill sequentially along the tow track, each one taking 12 minutes to fill. Deployment and recovery of the sampling sled will require the ship’s boatswain and a winch driver. Science personnel will handle interconnections of cables, tag lines and the mounting and removal of the integrating samplers.

Fig. 6. Tracer Sampling Sled. The auxiliary cable, on which 10 to 12 integrating samplers have been deployed, can be seen suspended from the sled.

Fig. 7. Integrating Sampler mounted on wire with sampling sled. There are 10 to 12 of these both above and below the sled, spaced between 4 and 10 meters apart.

Anticipated Science Party Jim Ledwell, WHOI, Chief Scientist Brian Guest, WHOI, Senior Engineering Assistant: Moorings, tracer release, float

deployments and tracer sampling. Cynthia Sellers, WHOI, Research Associate: Software, data processing and archiving. Leah Houghton, WHOI, Research Associate: Chemistry of injection and tracer analysis. Stew Sutherland, LDEO, Research Associate: Tracer release software and control. Peter Lazarevich, FSU, Research Associate: Mooring and float deployments. Nicolas Wienders, FSU, Research Associate: Computing, Moorings, Floats. Others from the oceanographic community would be welcome, as this is a small party. Gear Requests from SIO - details Mooring winch for sound sources. This is something for Brian Guest and Scott Worrilow to work out with SIO. Auxiliary winch for 50 to 100 meters of wire. This winch is usually placed near the CTD winch with the line fed through a block near the CTD block. Maximum load on it would be less than 1000 pounds. If there is something on the ship we can use, or if SIO can provide one, then great. Otherwise we will have to find one at WHOI and ship it. (2) Air Tuggers for recovery of the injection sled. XBT launcher and receiver, for 1500-meter XBTs. We will be relying on XBT profiles and only a few CTD profiles (if any) to choose the location of the tracer release, so this is important. Shipboard ADCP and Doppler. We would like currents as deep as we can get them. I note that the description of Revelle includes a 50-hz Doppler that reaches to 1000 m. This would be good for us. I am in touch with Rob Pinkel about use of this system. Rack for gas cylinders. We will have 8 tracer cylinders (liquid CF3SF5) that can be kept in a rack outside. We also will have 2 nitrogen cylinders which we would like in the lab or with lines fed into the lab. There will be no CO2 or other cylinders on this cruise, though they are noted on the UNOLS cruise request - these are for the cruise in 2010. CTD/Rosette. A CTD/Rosette frame is required for this cruise as a backup for our sampling system. A SeaBird 911+ CTD is needed as a backup for the injection CTD. This would be the CTD on the rosette frame. We will have 24 x 5-liter Niskin bottles from WHOI as part of the sampling system as well as 14 x 1.2-liter Niskins which fit on the injection and samlpling sleds. Rosette Pylons. We would like (2) 24-place SeaBird rosette pylons, ideally. One would be mounted in our injection sled and then moved to the sampling sled. The other would

be a spare, or would be used on the rosette frame mentioned above if for some reason we go to the CTD/rosette/5-liter bottles for sampling. Niskin Bottles. We request that all Niskin bottles, except the 5-liter and 1.2-liter bottles we bring, be left on shore. This is to avoid contamination of SIO Niskin bottles with the tracer, since we or others may use these bottles in the future for sampling this tracer. If they cannot be stowed on shore, then they should be removed from the rosette frame, and stowed in a container as air-tight as possible in the hold. Multibeam. We will not be able to provide a technician for multibeam. However, Multibeam data are of value to us. If the data can be gathered along the track during the cruise with the assistance of the resident technician, then we would like to do it. We will examine it during the cruise and we will take the data back to shore for cleanup up there. If the SIO computer technician is able to quality control and process the data, then all the better. GPS. We need float launch positions accurate to within 100 m. Communication. We will need fairly large files sent to us to help with tracking the tracer. These will be images, in general, on the order of 300 Kbytes. Pingers. We will bring a pinger on board the tracer sampling sled. A pinger on the CTD/rosette package is requested. Both of these are for recovery from unmentionable disasters - we do not plan to take either package close to the bottom. Refer van. We do not need one for this cruise, though it is noted on the original UNOLS request - this was for the 2010 cruise. Salinometer. We will run approximately 120 salinity samples during the cruise. We would like a salinometer on board, and 4 boxes of salt bottles. Oxygen titration. We do not need titrations for this cruise. The one requested on the UNOLS form was for the seconds cruise. Revision: We do need some oxygen titrations, perhaps 30 or so. If SIO can provide the equipment, then great. If SIO tech can run the titrations, even better. If not then I propose that one of the science party does them. Uncontaminated seawater. Not needed for this cruise unless someone signs up on an ancillary basis to analyze underway samples. IMET system. Not needed for our work. However, since this is a part of the ocean seldom visited, the meteorological instruments should be operating properly. Technicians needed. We will have plenty of expertise on CTD operations. Furthermore, we will be doing very few CTDs - maybe none other than those profiles taken with our

Jim Ledwell ! 7/18/08 4:53 PMDeleted: .

injection and sampling sleds. Technical expertise most useful to us will be on the ship's computer system, on the Doppler sounders, and the multibeam system for one, and on mooring deployments for the other.

Hazardous materials. The compressed gases: (CF3SF5 and Nitrogen) Vertrel-XF (C5H2F10) Radioactive Material (2) Electron Capture Detectors with 10 mC each of Ni-63 (sealed sources).