2012 Research Highlights
Our branch of ocean science focuses on the fluid-dynamic processes that shape ocean currents, the role of those flows in Earth’s climate system, and their interaction with the ocean geochemical systems and ecosystems. Scientists use a mix of approaches to address physical oceanographic research questions, including directly observing using instruments—operated in the field by scientists and technicians or sampling autonomously; designing and carrying out laboratory experiments; and applying analytical and numerical methods for solving the relevant dynamical equations. As of this writing, the WHOI Physical Oceanography department encompasses a scientific staff of 32 individuals and 17 postdoctoral scholars and investigators. These researchers are aided by a support staff of 60, with guidance from 15 scientist and oceanographer emeriti. There are currently 17 MIT/WHOI Joint Program students enrolled in a physical oceanography curriculum. The Department added one part-time employee in 2012 and lost 1 to retirement.
In 2012, PO Department staff members were engaged in approximately 225 active research projects. The focuses of these studies ranged geographically from the North Pole to the Southern Ocean and from the ocean abyss through the air-sea interface and into the atmosphere. The processes being examined ranged in spatial scale from millimeter to basin size, and in time scale from seconds to multi-century. PO researchers participated in approximately 26 major oceanographic cruises lasting up to 50 days and numerous 1-2 day trips, and contributed to countless workshops and scientific conferences.
A sampling of research highlights from 2012
SPURS surface mooring buoy on deck of R/V Knorr
After deployment, with Associate Scientist Tom Farrar in foreground
Several department members including Ray Schmitt, Dave Fratantoni, Lou St. Laurent and Tom Farrar are engaged in the Salinity Processes in the Upper Ocean Regional Study, a program investigating the ocean's role in the global water cycle. SPURS' initial focus is the 'sea surface salinity maximum' region in the eastern North Atlantic Ocean—the place where highest salinity surface water in the open Atlantic is believed to result from excessive evaporation associated with dry air originating over the North African deserts blowing out over the ocean. A variety of autonomous and human-supported ocean sensors are being utilized in SPURS, as well as information from a new NASA satellite that can "see" variations in sea surface salinity. The goal of SPURS is improve our understanding of the water cycle over the oceans and its ties to climate.
During the initial SPURS instrument deployment cruise in October aboard R/V Knorr, a voice call was arranged for Chief Scientist Ray Schmitt, NASA SPURS Program manager Eric Lindstrom and Knorr's Captain Adam Seamans to talk with Sunita "Suni" Williams, Commander of the International Space Station, who congratulated the team aboard Knorr on their SPURS expedition.
Still image from the video taken during the ROV Jason operation aboard R/V Knorr to recover the stuck DYNAMITE mooring. The knife held by Jason's manipulator arm sawed through the nylon rope mooring segment immediately above the anchor, allowing all of the instrumentation and other equipment on the mooring to be recovered. (See video above "Go Down Jason, Let My Mooring Go")
The Dynamics of Abyssal Mixing and Interior Transports Experiment, led by Ruth Curry and Kurt Polzin, is investigating the processes by which the densest waters in the Atlantic are transformed by vertical mixing into warmer, less-dense water classes (termed Lower North Atlantic Deep Water), and the circulation through the abyssal western North Atlantic basin that results from that mixing. The dense waters originate as stratified inflows from the south and north (called Antarctic Bottom Water and Denmark Strait Overflow Water, respectively). Along their flow paths, turbulent mixing causes these dense waters to entrain overlying warmer waters, changing the characteristics of the bottom flows, weakening their stratification, and making them more buoyant. The resulting upward transfer of mass has consequences for the ocean's abyssal circulation and for ocean budgets of heat, mass and tracers that are important to Earth's climate system. Ruth and Kurt conducted a field program focused on the region where most of the water mass transformation appears to take place: between 20° – 40° N. They found that turbulent mixing is enhanced over the rugged topography along the Mid Atlantic Ridge and Bermuda Rise.
The DynAMITE field program had two major elements.The first was a moored instrument array extending southeast away from Bermuda, whose purpose was to sample an abyssal flow that Ruth had inferred from historical observations. The second was a regional survey using traditional water sampling techniques and a specialized untethered profiler to sample the ocean mixing processes. Both program elements generated stressful periods: The profiler became stuck in the bottom for a week during its 2011 cruise before a dragging operation dislodged it; and one of the moorings failed to release after its 18-month mission. The mooring was successfully recovered in 2012 with a 2-ship operation in which ROV Jason aboard Knorr was used to cut the mooring free, and it was subsequently brought aboard R/V Atlantic Explorer.
Photograph of an Ice-Tethered Profiler shortly after deployment in open water, because there were no sufficiently large and strong ice floes in the area to allow normal deployment atop the ice.
Andrey Proshutinsky is lead investigator of the Beaufort Gyre Observing System in the Arctic Ocean, ably assisted by Rick Krishfield. Ice, ocean, atmosphere: these three components constitute the Arctic climate system. At its heart is one of the least studied bodies of water on the planet—the Beaufort Gyre, a clockwise swirling lens of icy water north of Alaska ten times the size of Lake Michigan. Recent observations suggest that because of global warming, the rhythms of the Beaufort Gyre have altered. To investigate what this means for the future of the Arctic climate, scientists from the United States, Canada, and Japan conduct annual, month-long expeditions to the region in summer to sample the water properties and deploy instruments that measure them throughout rest of the year. The 2012 cruise took place during of a record minimum in the late-summer horizontal extent of the sea ice pack, which complicated deployment of ice-based instrument systems. BGOS and other programs contributing to the Arctic Observing Network are returning observations that shed light on the processes driving Arctic change. A leading explanation is the "ice-albedo-feedback" mechanism, in which the ocean absorbs heat in leads between ice floes, causing the ice to melt, and making wider leads. Scientist Lisan Yu is studying an increasingly important additional factor, the role of low clouds lessening the loss of heat to space.
An albatross investigates a free-fall profiler used in the DIMES study to sample ocean mixing processes.
The study of turbulent mixing in the Southern Ocean (DIMES: the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean) continued in 2012 with a major expedition on the U.K. research vessel James Cook to Drake Passage and the Scotia Sea. Lead WHOI investigators in DIMES include Lou St. Laurent and John Toole from the PO Department and Jim Ledwell from the AOPE Department. During the cruise there were two medical evacuations to Port Stanley, Falkland Islands, and one of the WHOI free-fall profilers was lost (the same instrument almost lost in the DynAMITE program). These events constrained the measurement program, but the data that was collected buttressed initial findings that indicated the intensity of ocean mixing varies widely within the Southern Ocean. Regions where the ocean bottom is relatively smooth have relative weak mixing, whereas in the areas where the deep-reaching Antarctic Circumpolar Current and associated eddies encounter tall, rough bathymetry—such as along the Phoenix Ridge in the Drake Passage, the mixing is greatly enhanced. As the field program continues, DIMES investigators are exploring how this pattern of mixing influences ocean circulation.
The goal of the now-decade-long international SeaFlux research program, led by Carol Anne Clayson, is to produce high-resolution (in space and time) estimates of the turbulent air-sea heat and moisture exchanges globally, using satellite remote sensing data. 2012 saw the release of Version 1.0 of the SeaFlux product: initial estimates of turbulent surface heat fluxes and associated near-surface variables, including a diurnally (daily)-varying sea surface temperature. Data are available at 0.25 x 0.25 degree spatial and 3-hourly temporal resolution, covering the period 1998-2007. This new data set joins several other products based on marine-deck observations, weather model re-analyses and blended analyses (such as one from Lisan Yu and Bob Weller called the OAFlux product) that attempt to quantify air-sea exchange. Each product has strengths and weaknesses; the continuing research effort seeks to improve estimates of air-sea exchange and better quantify and understand the earth's evolving climate system.
Saqardliup Glacier, West Greenland
Associate Scientist Fiamma Straneo and colleagues conducting small-boat operations adjacent to Saqardliup Glacier in West Greenland (left),
including use of a REMUS AUV (right).
A collaboration between PO scientists (Fiamma Straneo and Al Plueddemann) together with Sarah Das (G&G), supported by the Arctic Research Initiative, led to the first successful survey of a tidewater glacier face in Greenland by an AUV. The research focuses on understanding why many of Greenland's tidewater glaciers accelerated in recent decades, leading to a rise in sea level and a freshening of the downstream ocean. Key to addressing these questions is collecting data where the glaciers meet the ocean - a dangerous and inaccessible region because of frequent iceberg calving. To acquire these data, WHOI scientists utilized a REMUS 200 AUV and a system of buoys to guide the AUV along the glacier face - collecting temperature, salinity and velocity observations. Amy Kukulya and Robin Littlefield (AOPE) conducted the REMUS field operations, together with Straneo and Das, in July of 2012. The science party (including Jeff Pietro and JP student Rebecca Jackson) camped for 9 days at the edge of Saqardliup Glacier in West Greenland - surveying the glacier edge and catching the occasional fish for dinner.
Surface Currents at MVCO
Fluid parcel trajectories
Example of a flow geometry in a simplified model of an ocean eddy.
Irina Rypina and Larry Pratt are investigating three-dimensional chaotic advection from a theoretical standpoint, to develop better understanding of mixing and stirring in ocean flows. The Lagrangian dynamics of fluid particle trajectories in time-dependent, three-dimensional fluid flows can be exceptionally complex. Irina and Larry are using dynamical systems theory to simplify the dynamics and identify some special relationships between variables characterizing a given circulation that shape the geometry of the flow. The image below shows an example of one such object arising in a simplified model of an ocean eddy. Each colored surface is produced from tracing the evolution of one fluid particle trajectory as it moves inside the eddy, and marking its position at discrete intervals of time. The outer blue and the inner red surfaces are topologically different from each other, and the black surface separates these two classes of trajectories. That black surface may be considered a barrier to the exchange of fluid particles across it. Predicting such surfaces for ocean flows will allow better quantification of the dispersion of, for example, pollutants. In a related study, Irina is collaborating with Anthony Kirincich to apply dynamical systems ideas to help interpret the MVCO ocean velocity data. Images from Larry and Irina's research are also contributing to an exhibit at the Boston Museum of Science entitled "Ocean Stories: A Synergy of Art and Science."
These highlights represent a small fraction of the research conducted by PO investigators in 2012. Deriving from these programs, approximately 70 peer-reviewed papers (co-) authored by PO Department investigators appeared in print in 2012, with a comparable number in press.
Continuing superior performance was recognized this year by these promotions: J. Thomas Farrar to Associate Scientist without Tenure, Daniel Torres to Research Specialist, Larry George to Engineer II and Andrew Davies to Engineering Assistant III. Congratulations all. Particular kudos go to Ray Schmitt, who was made Fellow of the American Geophysical Union this year.
—John Toole, Department Chair
2011 Research Highlights
The Physical Oceanography Department, in association with the Geology and Geophysics and Marine Chemistry and Geochemistry Departments, engaged in a scientific staff recruitment effort from 2009 to 2011 that focused on Climate Research. This search was very successful, resulting in the addition of 5 staff members with climate interests to the PO Department (three Assistant Scientists and two Associate Scientists with Tenure). Here we introduce these five investigators and showcase elements of their present research.
I. Much of Carol Anne Clayson's current research focuses on the global water and energy cycles. Using mostly satellite data, Carol Anne works with hydrologists and atmospheric scientists to estimate the uncertainties remaining in these cycles and investigating if, as climate change models suggest, the water cycle is indeed increasing in strength and if there has been a change in the number of weather and climate extremes across the globe. Early indications are that the distributions of weather events are indeed changing. Carol Anne is also investigating diurnal (day and night) sea surface temperature cycles, to accurately account for earth's heat and water budgets and to quantify the impact of diurnal variations on ocean-atmosphere feedbacks. Her analysis of ten years of data showed that if diurnal sea surface temperatures weren't included in the energy calculations for the tropical ocean, the estimated air-sea fluxes (the rates at which heat is exchanged between ocean and atmosphere) could be in error by up to ten Watts per square meter—an important finding that is helping to motivate continuing investigations of the diurnal sea surface temperature cycle and upper ocean mixing processes.
II. A major reason why the ocean is important for Earth’s climate is that the deep water can be out of contact with and isolated from the sea surface for very long periods of time. This allows carbon compounds taken up from the atmosphere by surface waters to be sequestered(isolated) at depth, reducing (at least temporarily) the amount of carbon dioxide in the atmosphere. The “age” of ocean waters, defined as the time since water was last at the surface, is a valuable way of characterizing the dominant time scales of the ocean circulation. Carbon-14 is a radioactive isotope long used to calculate the age of fossils, artifacts, and other objects, and also for dating ocean water. One of Geoffrey (Jake) Gebbie's research projects that examines how ocean mixing affects the interpretation of carbon-14 levels uses observations of water property, in conjunction with a circulation model, to individually track over 11,000 water parcels from their surfacing locations to the deep ocean interior (in contrast to previous estimates that typically tracked just a handful of surface source waters). Taking mixing properly into account increases the ocean water age estimates by several hundred years; Jake estimates that deep Pacific Ocean waters are well over 1,000 years old. His research suggests that the ocean played a strong role in the large climatic swings of Earth’s past, because ocean waters appear to be renewed on a similar timescale to the waxing and waning of large ice sheets during the Ice Age.
III. Amala Mahadevan studies the impact of upper-ocean physical processes on the distributions and cycling of chemicals between living organisms and the ocean environment. Phytoplankton at the base of oceanic ecosystem food chains are also important componentsof the ‘biological pump’—the process in which single-celled plants take up carbon dioxide and sink to deep waters when they die, removing the carbon from contact with the atmosphere. Phytoplankton grow in sunlit waters supplied with nutrients from the deeper waters. What controls the residence time of phytoplankton in surface waters before being carried to deeper/darker depths by currents? What currents transport nutrient-rich deeper waters to the surface? What controls the surface distribution of dissolved carbon, and carbon dioxide exchange with the atmosphere? How do upper-ocean physical processes facilitate the export of organic carbon to depth? Amala explores these questions with dynamical models that describe mixed-layers, fronts, eddies and internal waves. Her goal is to improve our understanding of the oceanic carbon cycle and its response and feedback to increasing atmospheric carbon dioxide and changing climate.
IV. While mechanisms inducing climate variability tend to have broad spatial scales, strong interactions among the earth system components often yield regionally-distinct patterns of change. Hyodae Seo seeks to understand how earth system components interact with each other to determine regional-scale climate variability, and, in turn, how these influence the local-scale climate processes relevant to human society. In one current project, Hyodae, working with others, has analyzed 30-year records of summertime water temperatures from coastal weather buoys and remote sensing data on the western U.S. continental shelf. His work reveals a significant cooling trend in sea surface temperature (at an average rate of about âÃ‚Â€Ã‚Â‘0.2 °C per decade) that is more prominent off south-central California than the Oregon-northern California coast. This coastal upwelling is an oceanic process poorly accounted for in climate models and data, but it appears to have intensified in the past 30 years due to more upwelling-favorable winds interacting with the regional coastal landforms. These small-scale climate signals that have significant implications for local weather, rainfall and diurnal cycles likely occur in coastal regions beyond the U.S. West Coast.
V. Temperature anomalies in the ocean (differences between observed temperatures and expected or average temperatures) persist much longer than the higher-frequency variability in the atmosphere. Better understanding of the links between sea surface temperatures (SST) and regional climate can help improve seasonal and longer term rainfall forecasts: a vital capability for water and agricultural management, as global populations continue to rise and uncertainty related to long-term climate change abounds. Caroline Ummenhofer studies SST variability and its role in modulating regional rainfall and drought. One of her foci is the Indo-Pacific and Australasian region, for which she combines observations, a wide range of model products, and paleoclimate reconstructions to identify patterns and investigate the physical mechanisms producing them. Such studies improve our understanding of the Indian and Pacific Oceans’ influence on drought in Indian Ocean-rim countries affected by monsoon systems over a range of timescales. The success or failure of the Asian monsoon can mean the difference between prosperity and severe hardship in the affected regions; clearly a better understanding of Indo-Pacific climate drivers on the monsoon is desirable.
Beyond these additions to the PO scientific staff, Postdocs Marieke Femke de Jong, Jean-Baptiste Gilet, Jeremy Kasper, Paolo Luzzatto-Fegiz. Melissa Omand, Gauher Shaheen, Robert Todd and Jinbo Wang, and Research Associate II Carolina Nobre joined the Department in 2011, while Magdalena Andres transitioned from Postdoc to Assistant Scientist. Senior Scientists Jim Price and Terry Joyce, Senior Research Specialist Dick Limeburner and Senior Information Systems Assistant I Jane Dunworth-Baker retired in 2011; the first 3 were subsequently appointed as Emeritus. Also leaving us in 2011 were Postdocs Liz Douglass and Emily Shroyer.
We applaud Emeritus Scientist Joe Pedlosky for being awarded the Maurice Ewing Medal from the American Geophysical Union, Associate Scientist with Tenure Lou St. Laurent for receiving the Nicholas P. Fofonoff Award from the American Meteorological Society, and Senior Scientist Bob Weller for being elected Fellow of the American Association for the Advancement of Science.
—John M. Toole, Department Chair
2010 Research Highlights
Our branch of ocean science focuses on the physics of ocean currents, the role of those flows in the earth’s climate system and their interaction with the ocean geochemical- and eco-systems. Physical oceanographic research involves a blend of approaches including direct observation using instruments operated in the field by scientists and technicians or sampling autonomously, design and carrying out of laboratory experiments, and application of analytical and numerical approaches to solving the governing fluid dynamical equations appropriate for a given problem. At the time of this writing in late December 2010, our department encompassed a scientific staff of 31 individuals with an additional 7 scientist emeriti and a combined postdoctoral scholar and postdoctoral investigator group of 8, who collaborate with and are supported by a technical staff of 64. In addition, there are currently 21 Joint Program students enrolled in a physical oceanography curriculum.
Many of the research activities highlighted in the 2009 annual report were sustained through 2010. Geographically, these investigations span all major oceans on the earth and nearly from pole to pole, from the very near shore regions to the deep. Below, a subset of these projects are summarized, working north to south:
• Several PO Department members carried out research projects focused on the Arctic Ocean and adjoining subpolar seas, many of which contribute to the long-term Arctic Observing Network (AON) effort. In 2010, Rick Krishfield supported the WHOI Ice-Tethered Profiler (ITP) program of drifting buoys deployed on Arctic sea ice as well as Andrey Proshutinsky’s sustained measurement program (Beaufort Gyre Observing System, BGOS) centered in the Canada Basin northeast of Alaska. ITPs were deployed near the North Pole in April using aircraft and in the Canada Basin in October from icebreaker, the latter in conjunction with the annual BGOS cruise during which an array of bottom-mounted moorings were serviced and ship sampling was conducted. One focus of these research efforts is the changing inventory of low-salinity surface waters that have been observed in the past to occasionally overflood the subpolar deep convection sites and shut down intermediate and deep water production for a time. Closer to the coast, Al Plueddemann led a team that deployed an autonomous underwater vehicle under the sea ice near Barrow, Alaska in March, while later in the year, Bob Pickart deployed moorings on the continental shelf that contribute to the AON and carried out shipboard sampling on two cruises, accompanied by postdoc Emily Shroyer. These studies are interested in documenting the Pacific Ocean waters that enter the Arctic through Bering Strait then spread east along the continental shelf and slope. On the theoretical front, Proshutinsky continued to direct the international Arctic Ocean Model Intercomparison Project whose annual meeting this year attracted more than 100 participants. In addition, Mike Spall investigated the relative role of air-sea buoyancy and wind stress forcing in driving overturning circulations in high-latitude marginal seas, while Jiang Yang studied the dynamics of the dense water overflows from such basins.
• Fiamma Straneo continued her innovative and challenging research program investigating the ocean influences on Greenland glaciers. In March she led a team to Sermilik Fjord to make the first wintertime observations of the ocean waters touching the base of the glacier. Owing to the absence of significant outflow of cold melt water from the glacier, the ocean temperatures in winter were warmer than what she observed the previous summer. Straneo returned to East Greenland in August-September to recover moorings that she had deployed in Sermilik and Kangerdlugssuaq Fjords the previous summer. Complementing this field work, Claudia Cenedesi has designed a series of laboratory experiments to investigate the dynamics of fjord ocean water interactions with a glacier tongue. This work has revealed the possibility of mid-depth intrusions of glacier-influenced waters extending from the glacier front, not unlike what Straneo has at times observed.
• At subpolar latitudes in the Atlantic Ocean, Amy Bower initiated a joint field program with German investigators looking at deep waters flowing through the Charlie Gibbs Fracture Zone, a series of deep passages through the MidAtlantic Ridge near 52°N. This moored array is planned to be in place for two years. Mike McCartney’s OCCI/ARI-funded glider program to sample the southward-flowing dense waters near Grand Banks returned one section across the current before the glider was lost; he is planning a second deployment in spring 2011. Dave Fratantoni contributed to several research efforts using ocean gliders, including using these autonomous instruments to acoustically track whales.
• Following the Atlantic deep waters further south, Ruth Curry together with Kurt Polzin initiated a measurement program in the area between Bermuda, Puerto Rico and the MidAtlantic Ridge to better understand the abyssal water circulation in this region and investigate the role of vertical mixing in driving that flow. The initial cruise of the program successfully deployed a moored array on the eastern flank of the Bermuda Rise in September despite significant interruption by Hurricane Igor. Curry is also involved in the Line W sustained measurement program with Terry Joyce, John Toole, McCartney and Lamont-Doherty Earth Observatory scientist Bill Smethie that is sampling the equatorward flow of the Deep Western Boundary Current over the continental slope southeast of Woods Hole. The 6-element Line W moored array was successfully recovered and redeployed in October. Joyce, together with Young-Oh Kwon, Fratantoni, Straneo, J.J. Park and postdoc Xujing Davis and others are continuing to analyze the CLIMODE observations obtained in the Gulf Stream during winter, and making comparisons together with Steve Jayne, Tom Farrar and postdoc Liz Douglass to the comparable region in the North Pacific sampled during the KESS program, while postdoc Magdalena Andres joined a research cruise looking at flow through the Ryuku Island arc.
• Anthony Kirincich has been busy this year installing and validating a new measurement system at the Martha’s Vineyard Coastal Observatory. Data from this multiple-antenna radar system is used to infer the surface velocity of the ocean over an approximately 6 by 12 mile swath south of the island. Anthony is planning to use this system to investigate the dynamics of the inner shelf circulation. Relatedly, new Assistant Scientist Irina Rypina is planning a massive surface drifter experiment within Kirincich’s sampling area to both validate the radar system and investigate natural flow boundaries within the ocean that may be explored using dynamical systems theory, a branch of theoretical fluid dynamics that Larry Pratt also studies. Complementing this coastal field work, Ken Brink and Steve Lentz engaged in theoretical studies of bottom boundary layers and topographic flow rectification.
• In the far western North Pacific, Jayne, Douglass, and Ken Decoteau (in support of Lou St. Laurent) participated in a cruise to study the evolution cold sea surface temperature wakes that develop behind typhoons (and hurricanes). This work called for a careful mix between the need to sample close to a storm but not too close! Also in the region, Glen Gawarkiewicz, Karl Helfrich and St. Laurent worked this year to analyze data obtained in previous years from the East and South China Seas with one focus being non-linear internal waves.
• Several PO Department members contributed to measurement programs in the Gulf of Mexico after the Deepwater Horizon oil platform disaster. Marshall Swartz prepared and mounted instrumentation aboard ships that sampled the water properties in the region of the spill; Dan Torres sailed on two of those cruises in June and July. In addition, Breck Owens and colleagues operated an ocean glider that surveyed the oil spill region autonomously, sending back data in real time via satellite. Jayne was secunded by the U.S. Coast Guard to assist with their evaluation of proposed oil spill mitigation strategies.
• Bower, Lentz, Farrar, Dick Limeburner and Jim Churchill were involved in field programs to the Red Sea in association with KAUST again this year. Highlights include an extensive hydrographic survey of the eastern Red Sea in March, and moored instrument deployments/recoveries in May-June and December. Jayne developed and taught a course to 60 students at the University in January/February.
• Ray Schmitt continued laying groundwork for the SPURS study of sea surface salinity variability in conjunction with the NASA Aquarius satellite. Lisan Yu and Bob Weller’s OAFlux air-sea exchange data set will contribute to this study using its estimates of ocean evaporation.
• The Upper Ocean Processes group had another busy year servicing their long-term surface moorings in the central low-latitude North Atlantic (Plueddemann lead), off Hawaii and west of Chile (Weller leads). In addition, UOP designed, built, provided to the Australian Government, and helped deploy a surface mooring south of Tasmania as part of the Australian IMOS (Integrated Marine Observing System). Weller and Farrar continued their sampling of eddy variability and vertical mixing in the upper ocean in the region around that latter mooring using underway CTDs and a Vertical Microstructure Profiler. Their work, in conjunction with analysis of data collected the year before with Straneo, seeks to quantify the different cooling and freshening processes at work in the upper ocean under the persistent stratus clouds that characterize this region. Kudos go out in particular to Jeff Lord and Ben Pietro for their efforts aboard the vessel B.I.C Humbolt to rescue the buoy off Chile that had gone adrift in July, and to Hazel Salazar for assisting with the logistics of that charter.
• As noted in last year’s report, Curry and Douglass completed the reoccupation of the 32°S hydrographic section initiated by Macdonald (Australia to Tahiti) with a January/February cruise (Tahiti to Valparaiso), and happened to return home just before the major earthquake that struck Chile later that month.
• St. Laurent, Toole, Krishfield, Decoteau and Dave Wellwood were at sea on the ill-fated DIMES (Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean) cruise southwest of Chile at that time (fortunately far enough away from the epicenter to experience no effects of the quake). However, earlier in the cruise R/V Thompson Captain Phil Smith suffered a major heart attack and died. Despite this tragedy, an extensive survey of the anthropogenic tracer that AOPE scientist Jim Ledwell deployed one year earlier was completed along with ocean turbulence observations done by the PO contingent. Both the tracer dispersion rate and turbulence data suggest that the vertical mixing in the Antarctic Circumpolar Current away from rough bathymetry is remarkably weak.
• The Neutrally-Buoyant Sediment Trap(NBST), a novel technology developed by Jim Valdes in conjunction with MC&G scientist Ken Buesseler, samples sinking biological material in the upper ocean over time periods of 1-30 days. In 2010, Jim and associates deployed NBST instruments off Bermuda (continuing a long-term program) and near the Antarctic Peninsula in the Southern Ocean – one of the latter marked the 100th deployment of NBSTs since the first in 2004 (with loss of only 2 systems over that time). Also this year, Jim began testing the next generation instrument he helped to develop: the Twilight Zone Explorer (TSEX).
• In mid December, Dick Limeburner and Will Ostrom (AOPE) traveled to McMurdo Station, Antarctica to install a set of velocity, temperature and salinity sensors in the waters below the floating tongue of the Ross Ice Shelf. Notably, the sensors are configured to transmit data to an electronics package sitting atop the ice, and then via satellite to WHOI. Limeburner reports that the Ross Sea Ice Shelf is the largest ice shelf in the world - about the size of France - and is 200-600m thick, overlying a seawater cavity that is about 600m thick; their observations represent the first real-time data from under an Antarctic Ice Shelf. In addition, this year Rick Krishfield supported New Zealand investigators who, at the same time Limeburner and Ostrom were working, deployed a WHOI Ice-Tethered Profiler in land-fast sea ice adjacent to the ice shelf. That system has been returning high-vertical resolution temperature and salinity information between 8 and 400 m depth 8 times per day since November 23.
• Three new Assistant Scientists joined the PO Department this year: Rypina, Jake Gebbie and Hyodae Seo. Rypina works to understand dispersion and transport barriers in geophysical flows using dynamical system theory and float observations. Gebbie and Seo were recruited under a multi-department Climate Initiative, begun in late 2009. Seo is a regional atmospheric modeler who is studying air-sea interaction in various environments. Gebbie applies models to diagnose ocean interior water property distributions in both the modern ocean and distant past, as well as to develop understanding of the tropical coupled ocean-atmosphere system.
• December 2010 marked the 50th anniversary of the first mooring deployment by the WHOI Buoy Group. The modern descendents of that facility: the WHOI Rigging Shop, Upper Ocean Processes Group, and Subsurface Mooring Operations Group, led by Rick Trask, Jeff Lord and Scott Worrilow respectively, continue the tradition, now having deployed in total nearly 1500 deep-ocean moorings. Amy Bower was presented with an Unsung Heroine Award by the Massachusetts Commission on the Status of Women, and elected Fellow of the American Meteorology Society. Glen Gawarkiewicz was recognized by the Taiwan National Science Council and U.S. Office of Naval Research for his 10 years of effort in support of the ASIAEX, VANS/WISE, and QPE programs. Other department members continue to work in service to the community: Mike Spall serves as Chief Editor of the Journal of Physical Oceanography and Ken Brink assumed a lead-editor position this year with the Journal of Marine Research, while Dave Fratantoni and Andrey Proshutinsky were named editors for the Journal of Atmospheric and Oceanic Technology and Journal of Geophysical Research, respectively. Ray Schmitt served on two National Academy Panels this past year: the first - "Advancing the Science of Climate Change" for the "America's Climate Choices" study, the second - "Marine and Hydrokinetic Energy Technology Resource Assessments." Bob Weller was appointed by the Secretary of the Navy to -, and approved for service on the “Ocean Resources and Research Advisory Panel.” Spall continued to serve on the Scientific Steering Committee for CLIVAR. In 2010, Joint Program students Jessica Benthuysen, Beatriz Peña-Molino, Tatiana Rykova and Katherine Silverthorne were awarded Ph. D. degrees while Rebecca Walsh Dell earned a Ms. degree and is continuing in the program.