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13 November 2012

posted Nov 13, 2012, 10:55 PM by Amy Waterhouse
Last night, Ruth and Kris Weeks stayed up over night to verify that we got the right spot for each of our three mooring sites. To do this, she watched as the ship passed over the three sites with the multi-beam echosounder (which maps the bathymetry of the ocean floor) to ensure that there was a flat area big enough for our moorings. The ship can chart the bathymetry real-time and she found three great sites at the ridge, the canyon mouth and the canyon head.

            (L) Ruth Musgrave (SIO) finding the best spot for our moorings. (R) Bathymetry for the ridge mooring location or Dancing man?

Paul Chua also ran through the plan for tomorrow as part of our science chat - making sure that everyone was aware of the deployment plan and the particular jobs that everyone was assigned.

After that, it was deployment time!

We started at the crack of dawn, and after a drift test, we started deployment just downstream from the final drop site. The first mooring is 1400m long, with a moored profiler which walks up and down 1200m of the wire collecting CTD (conductivity, temperature and depth) as well as velocity. There is another current meter 120m above the bottom of this mooring to capture any cool and interesting signals that might be happening down at the bottom of the canyon. Above and below the moored profiler, we taped on 10 temperature and conductivity loggers as well as beacons to the top float. By lunch time, this mooring was in the water and after ranging on the mooring, it was less than 100m off from our target site.

            (L) Paul, Jonathan and Amy ready at 6am.               (R) Alfredo Wetzel (UMichigan) changing his applied
                                                                                                         math hat for TSE winch operator hat

     We put temperature loggers on everything, even                 Releases ready to go, generously donated
                                our floatation!                                                           by Janet Sprintall (SIO)    

After lunch was over, we had steamed to our second drop site and started deploying that mooring. This one had two current meters - one long ranger ADCP near the top capable of measuring currents down to 500m and then another current meter 120m above the bottom. Over 23 temperature and conductivity loggers were strapped on this line, and everything was in the water (including the final anchor) before dinner. We triangulated the position by sending pings to the releases, and another successful target drop!

Almost all of the equipment for this cruise has been graciously donated for our UC ship funds trip from various people and we are extremely grateful to them, including: Jen MacKinnon, Shaun Johnston, Jonathan Nash, Uwe Send, Janet Sprintall, Rob Pinkel and Peter Worcester to name a few in a long list.

Tonight our science talk was by Jonathan Nash (OSU) who talked about big internal waves that he and his colleagues have been measuring off the Luzon Strait in the south China sea. These waves can be as big as 300m tall! We aren't expecting to see waves this big at Mendocino Ridge, but we expect to see some neat internal tides generated off the ridge and propagating up and into Eel canyon.