Check out this Scripps Explorations article highlighting work done by MOD’s Drew Lucas and Rob Pinkel on internal waves breaking right outside our offices.
Nice work!
Read the full JPO paper by Lucas and Pinkel here.
Updating the Revelle’s novel velocity measuring system
The MOD group has long specialized in Doppler sonar techniques, pioneered over 30 years ago by Rob Pinkel and Jerry Smith. For about 20 years, Scripps’ flagship the R/V Roger Revelle has carried a one-of-a-kind such system, the Hydrographic Doppler Sonar System (HDSS). Unlike conventional Acoustic Doppler Current Profilers carried on most ships, the HDSS has much higher power and much narrower beams, allowing greater precision, finer resolution in the vertical and greater range. While the Revelle is in dry dock for her midlife refit, our group is taking the opportunity to remove the HDSS from her hull, modernize it and reinstall it.
Many long hours have been spent underneath the Revelle.
It is a massive job and we have now successfully removed the old system, which requires hard work and long hours beneath the enormous ship. Creating the new system, which will have still higher power and will eventually allow better removal of the ship’s rolling and tilting from the measured signals, has involved long hours by the Marine Physical Laboratory machine shop and painstaking work repotting the transducers and cabling them. The final installation will take place in August.
Wish us luck!
Hydrographic Doppler Sonar System (HDSS) upgrade
The Hydrographic Doppler Sonar System (HDSS), is now 20 years old and is getting upgraded when R/V Revelle undergoes her midlife refit this summer and fall. HDSS is a state-of-the-art system for measuring ocean currents. We are substantially upgrading and improving the old system, with enhancements including greater power and real-time beam forming that corrects for the roll and pitch of the ship, improving precision by keeping the beams much more constant orientation.
Engineers Sara Goheen and Mike Goldin and Professor Rob Pinkel ultrasonically clean a cable from the old system in preparation for the installation this summer and fall.
MOD PIs chair first-ever Gordon conference on Ocean Mixing
Last week, the very first Gordon conference on ocean mixing took place in Andover, NH. 167 participants from all over the world learned about the state of the art of our field and its impact on other fields. It was enlightening, inspiring and a lot of fun!
The final countdown
Albatross fill the air, Tasman Island in the distance – the location for the TTIDE southern moorings. Photo: Thomas Moore
It’s the second weekend out here on the Tasman Sea for the TTIDE leg 3 crew aboard the R/V Revelle. Today we are pushing hard to finish recovering all four remaining moorings still in the water. If the team can make all that happen before darkness falls tonight that will keep the TTIDE project ahead of schedule and give the scientists extra time to conduct “yoyo” and “towyo” operations – filling important gaps in our view of the internal wave energy pulsing across the Tasman Sea. There are only a few days left until the R/V Revelle steams “back to the barn” and for all aboard it’s starting to feel a bit like the final countdown.
Dawn broke gray and chilly but the howling westerly wind and the short, steep windswell it generated has mercifully laid down. It was a great way to start the recovery of TTIDE “M4”, a 2300 metre tall mooring designed to capture the energy of internal waves breaking in the shallowing waters of the continental slope using two highly specialised McLane profilers.
The McLane profilers are “wire-crawlers”, programable robots that climb and descend the mooring line over and over and over again, one million metres worth of travel in every one of their large internal lithium battery packs. These profilers come jammed with an array of instruments that
A McLane profiler breaks the surface. Photo: Thomas Moore
measure pressure, temperature, salinity, and most importantly current velocity at a finer scale and across a longer vertical reach than any other tool in our oceanographic toolbox.
The McLane data are invaluable, they are costly acquire, and each profiler runs on hardware and software that takes great skill and experience to operate. The McLane profiler, often abbreviated as “MP” in casual conversation on the back deck, is the star of the show and everybody quietly anticipates the outcome each time one of these yellow beasts breaks the surface of the sea under the tug of our winches. Did the wire-crawler survive the pressures of the deep and what data will it hold for the TTIDE team?
The first analyses of MP data are underway
Science, caught fresh from the sea
The MP’s have indeed brought a data harvest, fresh from the sea. As moorings have been brought onboard the attached instruments are cleaned and logged before TTIDE team members get busy up forward in the analytical labs extracting the data onto a dizzying collection of hard drives.
Time is always short aboard ship but TTIDE scientists have started to look at the new MP data in the past 24 hours, building the initial analyses of what an underwater robot has learned from crawling a mooring wire for many months deep under the surface of the Tasman Sea. This first look at the MP data shows the clear fingerprints of the daily tide, lunar cycle, and the passing of swirling mesoscale eddies as they swept over the slope 20 kilometres or so off St Helens, Tasmania.
Prof. Matthew Alford works on a MP back in the ship’s lab. Photo: Thomas Moore
When the TTIDE scientists finally return home* they will bring all the fresh science they have caught into their data kitchen and cook up a better understanding of our earth, climate, and ocean.
[ by: Thomas Moore, for the TTIDE team ]
* “home” means many things for the diverse TTIDE team, made up of experts from the University of Minnesota – Duluth, the University of Alaska – Fairbanks, Oregon State University, the University of Washington, and the Scripps Institution of Oceanography.