Boundary Layer Turbulence - the experiment begins!

To prepare for our exciting Boundary Layer Turbulence Experiment (follow along with the cruise blog) our team has been working around the clock to prepare three different tools for the experiment:

1. Moorings that, together with instruments from Kurt Polzin at Woods Hole, will measure the turbulence and mixing of cooler water with the warmer water above. These required the usual attention to detail and care in packing and planning each element. Beyond that, we are adding a new element for this experiment: one of our profiling moorings will have an epsi to make turbulence measurements.

2. We’ll be needing to sample the dye cloud we release near the sea floor as fast as possible. So we have added a fluorometer to our fast CTD. Because the fast CTD rises and falls so fast and samples on both up and down casts, we’ll be able to sample the dye cloud up to 5 times faster than we would by using the standard ship’s CTD rosette.

3. We’ve made huge changes and improvements to the electronics, software and body of our beloved epsi profiler. Many of the electronics and software changes are invisible, but they greatly increase the reliability and usability of the system. The mechanical changes are more visible and more crucial for the BLT experiment, which only focuses on the bottom few hundred meters of a 2000-m-deep ocean. So we have: i) added a longer, 3000-m cable, to allow us to sample deeper; ii) designed a cool new facility for pressure testing all of our sensors to ensure they don’t have odd effects at depth; iii) completely rebuilt the instrument to be heavier and longer which will make it more sensitive and better at reaching the great depths; and iv) contrary to most microstructure profilers which simply fall slowly the entire way to the bottom like parachuters, epsi now has the ability to “skydive” wherein it keeps its drag screens retracted until receiving a command from above, at which time it “pops the chute” and falls slowly in the lower part of the water column which we care about. With an altimeter, We’ve tested and retested all of these features for months and months in the lab, on the R/V Beyster, and in the 10-m pool at our lab, and think we are ready to go. Indeed, our initial tests yesterday looked great.

Wish us luck - we’re doing new things with new tools and are excited.

The latest and greatest epsi profiler getting assembled in the lab.

Drawing of epsi diving quickly to depth and then popping its chute to take measurements close to the ocean floor.

Ready.....set.......

Though there have been some (substantial) fieldwork efforts going on here and there during this last pandemic year, like most of the world most of us have been stuck closer to home. With things stabilizing a bit (at least in the US) we are starting up again with our normal level of crazy :) Heading out in June are two fun and hopefully exciting projects in two very different parts of the world, looking at quite different things.

• The Boundary Layer Turbulence project will take place in the far North Atlantic. The MOD team and colleagues from several other universities will be delving into the deep dark ocean with some new tools, to see what processes turbulently mix water at the very bottom of the sea, where the ocean rubs on the seafloor. Spoiler alert - those ethereal lurking mysteries may hold a clue for how the whole ocean overturns. Stay tuned for more from them as they set sail soon.

• Half a world away, the SUNRISE project will take place in the sweltering Gulf of Mexico. This one is looking at surface processes, specifically how strong fronts associated with Mississippi and other river outflows interact with wind-driven oscillations in the surface ocean, and how they conspire to move heat, salt and nutrients around the coastal ocean.

Stay tuned for dueling updates!!

Pelicans gliding on ocean waves

MOD researchers Ian Stokes and Drew Lucas have recently developed a theoretical model that describes how the ocean, the wind, and the birds in flight interact in a recent paper in Movement Ecology. They found that pelicans can completely offset the energy they expend in flight by exploiting wind updrafts generated by waves through what is known as wave-slope soaring.

Photos by Simone Staff

In short, by practicing this behavior, seabirds take advantage of winds generated by breaking waves to stay aloft. Wave-slope soaring is just one of the many behaviors in seabirds that take advantage of the energy in their environment. By tapping into these predictable patterns, the birds are able to forage, travel, and find mates more effectively. “As we appreciate their mastery of the fluid, ever-changing ocean environment, we gain insight into the fundamental physics that shape our world,” said Lucas.

For more information, visit
https://jacobsschool.ucsd.edu/news/release/3261

Congratulations to our new PhD's

Congratulations to Drs. André Palóczy and Kristin Zeiden for completion of their PhDs.

In September of 2020, André Palóczy defended his thesis on the turbulence and cross-slope transport off Antarctica and California. Dr. Palóczy, co-advised by Jen MacKinnon, Sarah Gille and Julie McLean, combined modelling and field approaches in order to answer these compelling and complicated dynamics. This included being Chief Scientist on the R/V Sproul during the 2017 Inner Shelf DRI.

In February of 2021, Kristin Zeiden, co-advised by Jen MacKinnon and Dan Rudnick, completed her thesis on the broadband, multi-scale vorticity wake generated by flow past Palau. Dr. Zeiden used a combination of glider, mooring and drifter data to explore how small-medium scale eddies shed from the tip of Palau, by a combination of mean and tidal flow, combine and conspire to create a large-scale island wake.

We wish both André and Kristin the best of luck starting their new positions — André as postdoc in Norway in 2021 with Joe La Casce and Kristin as a postdoc at UW/APL with Jim Thomson. We will miss them!

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Drs. Kristin Zeiden and Andre Paloczy charting their bright futures.

Debuting our new towed Phased Array Doppler Sonar

Engineers Jonathan Ladner, Riley Baird and Sara Goheen are excited about the new instrument!

Though this year has been hard and different in so very many ways, one small up-side from the reduced fieldwork has been the opportunity to make progress with some new development projects. Building off of previous pioneering advances of Rob Pinkel, Jerry Smith and Mike Goldin, the group has been hard at work designing and building a new phased array. Normally, ‘Doppler Sonars’ in the ocean are mounted on a ship or moored, and measure a profile of ocean currents in one direction, by sending out acoustic signals, looking for the doppler shift of the reflected response from moving currents (think sound of passing trains), and range-gating the results to get a measure of ocean currents as a function, say , of depth below a ship. As a ship drives around, that allows us to map out ocean currents in two dimensions (depth below ship, and along the ship track). With a phased array, beams can be formed in multiple directions, allowing us to see a ‘wedge’ of ocean currents, not just a single profile. The hope of this new instrument is that if we tow a phased array behind a ship, it can map out volumes of near-synoptic ocean currents, which will let us better understand the complex and rapidly evolving structures of turbulence, submesoscale instabilities, frontal dynamics, and more! Last week the team headed out on the R/V Sproul and did some debut towing and testing of our new vehicle.

MOD scientists in Ghana

Every August since 2015, oceanographers from around the world board flights bound for Kotoka International Airport in Accra, Ghana. Upon arrival, these scientists meet up with Dr. Brian Arbic, from University of Michigan, and local oceanography faculty at the University of Ghana to host a summer school aimed at strengthening the West African involvement in global oceanographic research.  

This August, however, in the midst of the COVID-19 pandemic, Anna Savage and Drew Lucas logged in to a Zoom meeting scheduled for 3 PM Accra time (8 AM California time, which was, admittedly, a little early for Anna) and watched the participant count increase from 6 to around 50. This year, as with everything, the entirety of the oceanography summer school was transitioned to operate remotely. Through a mix of Zoom meetings, pre-recorded YouTube videos (such as Anna’s), and a collection of well organized Slack channels, instructors were able to interact with the over 250 participants over the five day event, covering topics from ocean acidification to remote sensing to the obstacles of women in STEM fields. The asynchronous lectures, hosted on YouTube and linked both in Slack and on the summer school’s website (coessing.org), were accessible to participants throughout the week, while the lecturers also hosted virtual office hours. This combination of scheduled “face-to-face” office hours and pre-recorded content provided the participants the opportunity to interact with instructors in real-time, building a sense of community, while still allowing participants to attend the summer school on their own time, something that is increasingly important as we all continue to work from home.

While the community of instructors looks forward to being in Ghana again next year, there is value in these exercises in distance learning, even when that distance spans oceans. The importance of in-person meetings is undeniable and yet, the relationships amongst the participants and instructors are built on respect and communication, not solely on proximity.

MOD students design and execute a novel kelp turbulence experiment - in a pandemic

A student-designed project to measure the flow around the Point Loma Kelp Forest kicked off this week with the successful deployment of an Acoustic Doppler Current Profiler (ADCP) within the kelp forest. The project was designed by MOD graduate students Bethan, Alex, and Noel, along with fellow graduate student Manuel Gutierrez-Villanueva, for a proposal writing and experiment design class taught by MOD PI Matthew Alford and SIO professor Uwe Send. The project investigates how the presence of vegetation affects coastal flow and the rates of turbulent dissipation outside the kelp forest and within its interior. 

Through the support of UC SHIP Funds and the SIO Scientific Diving Program, operations will continue over the coming weeks with ship surveys aboard the R/V Robert Gordon Sproul to measure ocean velocity, and small-boat operations to collect the first-ever microstructure measurements within a kelp forest using the recently-upgraded epsi-fish, our microstructure profiler. The results of this project will help us understand how physical processes, important for the exchange of nutrients and spores, interact with the Point Loma Kelp Forest, the largest giant kelp bed in Southern California and home to many invertebrates, fishes, and marine mammals.

MOD graduate student and scientific diver Alex Andriatis (right) with fellow grad student Anela Akiona (left) after a successful ADCP deployment in the Point Loma Kelp Forest. Thanks to Jennifer MacKinnon and Amy Waterhouse for loaning the ADCP, and to Tyler Hughen and Paul Chua for assisting in preparing it.

We expect four different physical regimes to exist in the area surrounding the Point Loma kelp forest (detailed in left column). To observe and understand their dynamics, we designed ship transects (pink dotted lines), ADCP deployments (red triangles), and microstructure sampling stations (purple stars) around the forest’s boundaries.

Congratulations to our new PhD's

The MOD group has produced two new PhDs!

It was this past September that Madeleine Hamann defended her dissertation titled “The dynamics of internal tides and mixing in coastal systems”, chaired by Matthew Alford. Maddie continues to work at Scripps as a postdoc.

Just a month before this, Elizabeth Fine defended her dissertation titled "Microstructure observations of mixing and turbulent heat fluxes in the western Arctic Ocean”, co-chaired by Matthew Alford and Jennifer MacKinnon. Effie is now at WHOI as an institutional postdoc.

Congratulations to them both and we wish you the best of luck in your future endeavors!

Deep Sea Mining - PLUMEX

Thanks to some very clever Scripps engineers, the UC ship funds program and the MIT environmental solutions seed funds, we did some work that should move the needle forward on our understanding of the potential impacts of deep-sea mining and whether that would ever be a good idea as we move towards electrification.

Read the full article on the MIT website: http://news.mit.edu/2019/understanding-impact-deep-sea-mining-1206

Learning about physical oceanography through dance

A visit of 5th and 6th graders from Escondido to the MOD labs and the Scripps campus this past Saturday marked the end of an unusual class setting: Learning about physical oceanography through dance. Over several sessions in the past few weeks, the students heard about ocean physics and ocean observations from physical oceanographers Larry Pratt and Gunnar Voet. In between the lessons, the students, together with their dance teacher Roxanne Rojas de Blanco, came up with dance moves to transform what they had just learned into a choreography. With a lot of creative energy the students danced ships in stormy seas and subsurface oceanographic moorings knocked over by strong currents.

Dancing wave orbits.

Larry Pratt answering student questions.

During their Scripps visit, the students carried out tank experiments to learn about density in the ocean. To put into action what they had learned about moored observations, they tested an acoustic release. A walk across the campus ended on the Scripps pier with seal, leopard shark and sting ray sightings.

Visiting the test pool at Scripps.

Students observing dense water plumes in tank experiments on ocean density.

Sending a ping through the acoustic deckset…

…and making sure the acoustic release responds.

Many thanks to Roxanne at A Step Beyond and our colleague Larry Pratt from WHOI for organizing this workshop, and to the National Science Foundation for financial support through our Samoan Passage research project!