center column 4 Why Antarctic Polar Ice is Melting: Robotic Ocean Gliders Discover Impact of Eddies Caltech researchers discover, using robotic ocean gliders, how warm water is making its way to Antarctic ice sheetsâ€“and how this warming ultimately leads to rising ocean levels. By JESSICA STOLLER-CONRAD Published on Monday, November 10, 2014 | 11:06 am Pasadena’s ‘626 Day’ Aims to Celebrate City, Boost Local Economy Community News Credit: UEA/CaltechCredit: Andrew Thompson/CaltechThe rapidly melting ice sheets on the coast of West Antarctica are a potential major contributor to rising ocean levels worldwide. Although warm water near the coast is thought to be the main factor causing the ice to melt, the process by which this water ends up near the cold continent is not well understood.Using robotic ocean gliders, Caltech researchers have now found that swirling ocean eddies, similar to atmospheric storms, play an important role in transporting these warm waters to the Antarctic coastâ€”a discovery that will help the scientific community determine how rapidly the ice is melting and, as a result, how quickly ocean levels will rise.Their findings were published online on November 10 in the journal Nature Geoscience.“When you have a melting slab of ice, it can either melt from above because the atmosphere is getting warmer or it can melt from below because the ocean is warm,” explains lead author Andrew Thompson, assistant professor of environmental science and engineering. “All of our evidence points to ocean warming as the most important factor affecting these ice shelves, so we wanted to understand the physics of how the heat gets there.”Ordinarily when oceanographers like Thompson want to investigate such questions, they use ships to lower instruments through the water or they collect ocean temperature data from above with satellites. These techniques are problematic in the Southern Ocean. “Observationally, it’s a very hard place to get to with ships. Also, the warm water is not at the surface, making satellite observations ineffective,” he says.Because the gliders are smallâ€”only about six feet longâ€”and are very energy efficient, they can sample the ocean for much longer periods than large ships can. When the glider surfaces every few hours, it “calls” the researchers via a mobile phoneâ€“like device located on the tail. This communication allows the researchers to almost immediately access the information the glider has collected.Like airborne gliders, the bullet-shaped ocean gliders have no propeller; instead they use batteries to power a pump that changes the glider’s buoyancy. When the pump pushes fluid into a compartment inside the glider, the glider becomes denser than seawater and less buoyant, thus causing it to sink. If the fluid is pumped instead into a bladder on the outside of the glider, the glider becomes less dense than seawaterâ€”and therefore more buoyantâ€”ultimately rising to the surface. Like airborne gliders, wings convert this vertical lift into horizontal motion.Thompson and his colleagues from the University of East Anglia dropped their gliders into the ocean off the coast of the Antarctic Peninsula in January 2012; the robotic vehicles then spent the next two months moving up and down through the water columnâ€”diving a kilometer below the surface of the water and back up again every few hoursâ€”exploring the Weddell Sea off the coast of Antarctica. As the gliders traveled, they collected temperature and salinity data at different locations and depths of the sea.The glider’s up and down capability is important for studying ocean stratification, or how water characteristics, such as density, change with depth, Thompson says. “If it was only temperature that determined density, you’d always have warm water at the top and cold water at the bottom. But in the ocean you also have to factor in salinity; the higher the salinity is in the water, the more dense that water is and the more likely it is to sink to the bottom,” he says.In Antarctica the combined effects of temperature and salinity create an interesting situation, in which the warmest water is not on top, but actually sandwiched in the middle layers of the water column. “That’s an additional problem in understanding the heat transport in this region,” he adds. You can’t just take measurements at the surface, he says. “You actually need to be taking a look at that very warm temperature layer, which happens to sit in the middle of the water column. That’s the layer that is actually moving toward the ice shelf.”The results from the gliders revealed that the heat was actually coming from a less predictable source: eddies, swirling underwater storms that are caused by ocean currents.“Eddies are instabilities that are caused by ocean currents, and we often compare their effect on the ocean to putting a spoon in your coffee,” Thompson says. “If you pour milk in your coffee and then you stir it with a spoon, the spoon enhances your ability to mix the milk into the coffee and that is what these eddies do. They are very good at mixing heat and other properties.”Because the gliders could dive and surface every few hours and remain at sea for months, they were able to see these eddies in actionâ€”something that ships and satellites had previously been unable to capture.“Ocean currents are variable, and so if you go just one time, what you measure might not be what the current looks like a day later. It’s sort of like the weatherâ€”you know it’s going to be warm in the summer and cold in the winter, but on a day-to-day basis it could be cold in the summer just because a storm came in,” Thompson says. “Eddies do the same thing in the ocean, so unless you understand how the temperature of currents is changing from day to dayâ€”information we can actually collect with the glidersâ€”then you can’t understand what the long-term heat transport is.”In future work, Thompson plans to couple meteorological data with the data collected from his gliders. In December, the team will use ocean gliders to study a rough patch of ocean between the southern tip of South America and Antarctica, called the Drake Passage, as a surface robot, called a Waveglider, collects information from the surface of the water. “With the Waveglider, we can measure not just the ocean properties, but atmospheric properties as well, such as wind speed and wind direction. So we’ll get to actually see what’s happening at the air-sea interface.”In the Drake Passage, deep waters from the Southern Ocean are “ventilated”â€”or emerge at the surfaceâ€”a phenomenon specific to this region of the ocean. That makes the location important for understanding the exchange of carbon dioxide between the atmosphere and the ocean. “The Southern Ocean is the window through which deep waters can actually come up to ‘see’ the atmosphere”â€”and it’s also a window for oceanographers to more easily see the deep ocean, he says. “It’s a very special place for many reasons.”The work with ocean gliders was published in a paper titled “Eddy transport as a key component of the Antarctic overturning circulation.” Other authors on the paper include Karen J. Heywood of the University of East Anglia, Sunke Schmidtko of GEOMAR Helmholtz Centre for Ocean Research-Kiel, and Andrew Stewart, a former postdoctoral scholar at Caltech who is now at UCLA. Thompson’s glider work was supported by an award from the National Science Foundation and the UK’s Natural Environment Research Council; Stewart was supported by the President’s and Director’s Fund program at Caltech. 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By Marcos Ommati/Diálogo September 25, 2017 In March 2017, Peru was impacted by El Niño Costero, a weather event characterized by an unusual heating of the ocean along the coast of Peru and Ecuador. In Peru, the phenomenon affected more than a million people nationwide and left more than 100 dead. Despite the tragedy, Peru co-hosted the 2017 South American Defense Conference (SOUTHDEC) along with the United States, through U.S. Southern Command (SOUTHCOM). Peruvian Minister of Defense Jorge Nieto Montesinos addressed the participants during the opening ceremony. Diálogo took the opportunity to speak with him about some national security issues.Diálogo: Many of the countries present at SOUTHDEC helped Peru with its humanitarian aid efforts after El Niño Costero.Peruvian Minister of Defense Jorge Nieto Montesinos: I want to thank them for that, and I want to thank all of the countries as well as the government, but also everyone here who helped us during the emergency this summer, giving us aid and sending us materials; for example, equipment to be able to respond to the emergency that we had to face in that moment. And I want to reiterate that your aid was very useful and that our Armed Forces and our entire government were able to effectively use it to benefit our people.Diálogo: How is the Ministry of Defense participating in the reconstruction phase?Minister Nieto: We have been very proud of the involvement of our Armed Forces during the response to El Niño Costero. Admiral [José] Paredes, [the chief of the Peruvian Armed Forces Joint Command] is with me on that. He was the one who led the operation for the deployment of troops at that time. Now we are in the reconstruction phase. We are helping with the work we were asked to help with. We are waiting for the process to move forward, for the project to develop further, and we will be expecting to participate in whatever ways we are asked to.Diálogo: What is the significance for Peru of jointly organizing the South American Defense Conference with the United States?Minister Nieto: In the first place, I want to express my gratitude that on this occasion this meeting is taking place in our country. It is a show of friendship and also of trust in the possibility of appropriately doing the work involved in organizing a meeting like this. The meeting, which begins today, is extremely important. The purpose of this meeting is to discuss experiences relating to issues of terrorism, the issue of cyber defense, and issues concerning trafficking, particularly drug trafficking. The experiences our various countries have had in facing these problems are gathered, knowledge is exchanged, and thus we try to improve the capacities of our Armed Forces in order to confront the problems they may be faced with.Diálogo: Are these new problems or threats?Minister Nieto: Just a few years ago, we thought we were entering a much safer world, but a decade, a decade-and-a-half later, that is not the reality. We have the same uncertainties as we had in the past, but they may have changed. Add to that a new kind of uncertainty, and as an old author says, those uncertainties were part of our lack of knowledge about the world. These uncertainties are often the result of our knowledge of the world. The problem that typifies this is global climate change, which stems solely from the actions of humankind and from our capacity for development applied to production without the controls necessary to avoid that aspect of the problem – the environment in which we live. And as such, these new uncertainties that often stem from our knowledge have to be studied from every perspective, given that they are global problems. And these global problems are seen in every corner of the world and therefore generate many perspectives through which to see them. Therefore, we need meetings like this one that allow for an exchange, analysis, and evolution, because we are facing problems that are often new or old problems that have taken on a new form, but about which we are receiving information, having experiences, and getting knowledge every day that needs to be put on the table and exchanged so that we all learn together and so that we are all able to find appropriate ways of making our world more secure.Diálogo: What are the Ministry of Defense and the Peruvian Armed Forces doing to decrease the production of coca in Peru?Minister Nieto: The issue of drug trafficking is an issue for our National Police, which is making enormous efforts to combat it. Our Armed Forces, especially in the Valley of the Apurímac, Ene and Mantaro rivers [VRAEM, per its Spanish acronym], have a responsibility, and we support the work of our National Police. They are using every measure necessary to keep it under control. As you know, the problem of cocaine trafficking is not a problem that has only a political solution or only a military solution. There is a set of problems that have to be faced and addressed to be able to reduce cocaine trafficking: from the issue of the global demand that exists for this type of product to everything having to do with the supply of chemical products necessary for its production, or the flow of money through financial channels that allows for specifically controlling this process – this international criminal activity. Our Armed Forces are permanently engaged in this. We have just received various reports on this from VRAEM, and we are working hard on it. So much so, that the problem is beginning to evolve in our country, and areas where the work of criminal groups was mostly based are now being displaced to other areas around the country. We are also working to stay up to date on this. Recently, we had a conversation with Brazilian Minister of Defense [Raul Jungmann] about this issue, to work together in a combined way along our shared border, taking charge of this problem because it is a transnational problem.Diálogo: Is there still a Shining Path presence in VRAEM?Minister Nieto: What we have in VRAEM is the remains of, what is left over from what was once the Shining Path. In reality, it is a family clan, the Quispe Palomino family clan, which has now left behind practically any strategy for power and has basically devoted itself to providing cover and travel services to drug trafficking gangs. So we still have the problem, it’s there. The geographic setting in VRAEM is very complicated. It is a very complex jungle, very intricate, with many geographic complications. They are basically all in one area, and we are working on that. We are working to contain their activities.
Weeks Marine’s new hopper dredge Magdalen has arrived in Buxton (NC) to take part in one of the State’s most critical projects, the Buxton Beach Nourishment scheme.Last week, Weeks’ President Richard S. Weeks announced that the single largest investment in the company’s 99-year history, the Magdalen will start her first project in North Carolina.“We are looking forward to observing her at work and integrating her into our dredging and marine construction family,” said Mr Weeks.The introduction of the Magdalen has effectively doubled Weeks’ hopper dredging capacity. The RN Weeks and BE Lindholm, the company’s workhorse hopper dredges, have combined hopper capacity less than the one of the new dredge.Prior to her arrival, the Buxton Beach Nourishment project was 74% complete with dredge RN Weeks performing the pumping operations.Weeks Marine reported earlier in December that approximately 2 million cubic yards of sand (out of the total 2,600,000) has been placed on the beach.