1. Cruise Track and Deployments
Blue circles: sound sources; Small blue dots: SOLO floats; Red dots: CTDs; Black dots: RAFOS triplets; Green patch: Tracer injection and sampling area. Map by Peter Lazarevich.
Cruise Track and Deployments

2. Typical Weather
Magdalena Carranza and Uriel Zajaczkovski and others kept an eye on the underway systems. Magdalena made these plots, and many others like them.

3. Data reduction and graphics done by Uriel Zajaczkovski and Magdalena Carranza
Mooring Site 1

4. Sound Source
Brian Guest with a Webb sound source. It’s a good thing Brian did not come down with the measles prior to this cruise. We would have had to wait until next year for DIMES to start, for the most part.

5. RAFOS Float Deployments
75 RAFOS deployed in all, in triplets. Led by Peter Lazarevich, Nico Wienders and Brian Guest.
RAFOS Float Deployments

6. We put these in for AOML. Peter and Nico took responsibility.
Drifter Deployments

7. EM-APEX Float Deployment
Byron Kilbourne represented James Girton on this cruise, and kept on top of the EM-APEX floats, before and after deployment.
EM-APEX Float Deployment

8. The EM-APEX appear to be performing as advertised
The EM-APEX appear to be performing as advertised. Three of them have been deployed on this cruise, all in the area of the tracer release.
EM-APEX Trajectory

9. Shearmeter Deployment
Tim Duda and Brian Guest designed this deployment method, which worked extremely well. Four Shearmeters were deployed in the tracer area. One went too deep and came back. We were unable to find it. The others are presumably sitting at some suitable depth spinning with the shear. The photo is by Captain David Muline, who did a lot more than take pictures for us. Not the least: keep us safe in a field of icebergs that seemed attracted to tracer.

10. 105 W Line
The CTDs were distributed with guidance from SSH from altimetry, and augmented with XBTs.

11. The Polar Front shows up where T at the temperature minimum near 200 meters passes from more than 3 degrees to less than 2 degrees, going south. Graphic prepared by Cindy Sellers, who is data central for the cruise and after.
CTD/XBT T Profiles at 105 W

12. LADCP Profile Red: E-W velocity, u Green: N-S velocity, v -5 5 cm/s
The LADCP functioned properly throughout the cruise. There appears to be plenty of shear in this example in the upper 1500 meters, to drive diapycnal mixing. Graphics prepared by Peter Lazarevich and Nico Wienders, who kept on top of the LADCP operation. -5
5 cm/s

13. Temperature section at 105 W
The Polar Front shows up clearly at 59 S. The SAF is more spread out from 57 to 53 S. The dashed line is where the break in time occurs between the two segments of the section: 50 to 58, then a 2-week absence, then 60 to 58 S. This graph and the sections to follow were prepared by Ryan Abernathey, who has kept our dynamic methods honest.
Temperature section at 105 W

14. The Polar Front shows up clearly at 59 S
The Polar Front shows up clearly at 59 S. The SAF is more spread out from 57 to 53 S.
Salinity Section at 105 W

15. Neutral Density Section at 105 W
The Polar Front shows up clearly at 59 S. The SAF is more spread out from 57 to 53 S.
Neutral Density Section at 105 W

16. Zonal Velocity from 105 W Section
The Polar Front shows up clearly at 59 S. The SAF is more spread out from 57 to 53 S. We don’t quite get the surface velocity to agree with the velocity from SSH. The latter, if used as a reference, gives unrealistically large velocities at the bottom.
Zonal Velocity from 105 W Section

17. The black line is where the CTD section was occupied
The black line is where the CTD section was occupied. The red rectangle is roughly where the tracer was released and sampled, in a relatively flat area in SSH, and in fact near an meander to the west. This map was prepared by Valery Kosneyrev, back at WHOI, who sent us SSH data daily.
Sea Surface Height, 8 Feb 2009

18. ADT Velocity around Tracer
Geostrophic velocity for the surface from the altimetry estimated for 2/9/09. The red rectangle is where the tracer was released and sampled. Data provided by Valery Kosneyrev. Calculation and graphics by Cimarron Wortham.
ADT Velocity around Tracer

19. ADCP/Satellite comparison 1
A time when the ADCP and geostrophic velocity from SSH compared well. Prepared by Cimarron Wortham.

20. ADCP/Satellite Comparison 2
A time when the two velocities did not compare well.

21. Velocity Estimates from CTD Box Survey
Geostrophic velocity at 1500 dbar from the grid of CTD stations around the tracer release area. A velocity is calculated for each pair of stations in the grid and shown roughly perpendicular to the line between the stations. The reference used was the surface velocity from the SSH. The red rectangle is the actual area of tracer activities. One can see that we were at a meridional convergence, balanced by zonal divergence. There is also a hint of clockwise rotation inside the box. The direction of flow at the center is ambiguous, but indications were that the velocity there was small. Calculations and graphic by Cimarron Wortham.
Velocity Estimates from CTD Box Survey

22. Tracer Patch
Solid red tracks: Tracer injection; Dashed tracks: sampler tows for tracer, with red indicating tracer found, black not found; Tow 2 actually did find some tracer, but none at the target density surface. The zonal tracer track at 58.2 S found tracer the first time through, but the array did not trip properly so few samples were obtained. On the repeat, Tow 5, no tracer was found. The larger numbers indicate CTD stations at which tracer was sampled, again red indicates tracer found, black not found. A SOLO float, 3 RAFOS floats, a Shearmeter and an EM-APEX float were released in the circle shown. The SOLO went to the bottom of the page after 10 days, as did the EM-APEX, the surface locations of which are shown with blue dots, with the numbers indicating the days since release. So both floats went to the same place, but they did not lead us to tracer, at least it seemed.

23. Injection Tow Data Time (days)‏
Hydrographic variables during the first tracer streak injection. The system is designed to stay at the target density of The density excursions are due to ship heave, to which the winch cannot respond. Excursions in the other variables are due to fine structure and internal waves along the tow track. Stew Sutherland, of LDEO, is responsible for the software and winch control hardware that makes towing the injection system and the sampling array on an isopycnal surface possible.
Time (days)‏
Injection Tow Data

24. What’s towed is an array of 20 integrating samplers, spaced about 4 meters apart above and below a sled with a CTD. They take 10 hours to fill. At the sled is an array of 50 syringes, filling sequentially over the 10 hours, to give us an idea of where along the tow track the tracer is found. The sled is kept at the target density surface. Leah Houghton and I did the GC analysis for this cruise.
Tow 1 Vertical Profile

25. A skinny, off-center profile, characteristic of the edge of a sheared streak perhaps.
Tow 2 Vertical Profile

26. Looks like a pair of profiles on top of one another – one broad and modest in concentration and the other sharp. This kind of thing can happen over a 10- mile tow.
Tow 3 Vertical Profile

27. Mean Tow Profile
Mean profile for the three tows that yielded tracer. The lump in the deep part comes from Tow 1.

28. Tracer Profile from Cast 29
Tracer Profile from Cast 29. In bad weather we reverted to CTDs rather than the towed system, which is tricky to deploy and recover without damage. The target density was In the following figures I will show all the CTD tracer profiles that contribute much to the mean. The others were of low or no concentration. These are plotted versus density because we were using the CTD at every sample. For the towed samples shown above, we only know the density at the central sampler, at 0 height.
CTD Cast 29 Profile

29. CTD Cast 38 Profile
CTD Cast 38 Tracer profile. Peak below the target surface.

30. CTD Cast 47 Profile
Tracer profile from Cast 47

31. CTD Cast 58 Profile

32. CTD Cast 59 Profile

33. CTD Cast 61 Profile

34. CTD Cast 63 Profile

35. If you look at the station map you might wonder to what extent we resampled the same spot. I do wonder.
CTD Cast 64 Profile

36. Mean Profile from CTDs, versus density
The peak and center of mass are a bit below the target surface, as is the case for the mean profile from the towed samplers. The error bars are smaller because there are more profiles and they were perhaps a bit more consistent with one another. But the towed array samples much more of the water on each cast (10 miles) and so those profiles should be taken seriously. I have not yet worked out the way to weight the tow sets properly. But they tell pretty much the same story.
Mean Profile from CTDs, versus density

37. Mean density versus depth
This profile is from all the CTDs, the bottle data used for the tracer sampling within the tracer region. We use this nearly linear relation to convert the tracer profile shown in the previous slide to z-space in the next slide.
Mean density versus depth

38. Mean Tracer Profile versus Depth
So here is the mean profile versus depth, obtained through the mean depth versus density relation and the mean tracer versus density result. Again the peak and center of mass are below the target surface, as for the towed array profile. The profile is more symmetric than for the towed array, and suggests a very narrow initial condition for the experiment – the rms spread about the center of mass is 5.5 m. This sort of profile is what we are after with our tracer injection. More data would not have been redundant by any means, but I think we can have reasonable confidence in the initial condition. If the diffusivity is only 0.1 cm^2/s, the rms spread after a year will grow to about 25 meters, and the second moment of the tracer distribution then of 600 m^2 will swamp the second moment here, of about 30 m^2, and its uncertainty.
Mean Tracer Profile versus Depth