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Glider transforms knowledge of Red Sea in 1000 dives

Lloyd Smith, supervisor of marine electronics from the University's Coastal and Marine Resources Core Lab (CMOR), repairs the glider that completed 1,000 dives in the Red Sea on November 22, 2015. Photo by Ryan Yangyang.


For KAUST Ph.D. student Nikolaos Zarokanellos from the University’s Red Sea Research Center (RSRC), nothing is more fascinating than studying the unknowns of the world’s oceans.

“I grew up in a town about 3 kilometers away from the sea near Patra, Greece, and spent most of my free time at the beach,” he said. “I was fascinated by the fact that despite all the technological advances we have, we’re not able to explore the oceans to the level we want. We made it to the moon, but we are still struggling to explore life in the deepest parts of the oceans and understand marine organisms living there.”

Zarokanellos completed his bachelor’s and master’s degrees in marine science at the University of Thessaly in Greece, and then worked for three years at the Hellenic Centre for Marine Research (HCMR), Institute of Oceanography as a marine data manager before coming to KAUST.

“HCMR previously closely collaborated with KAUST, so I learned about the University and its great facilities and opportunities while working there. I was especially interested in assisting to start a glider program at KAUST, in which researchers use autonomous underwater robots to understand the physical and biological variability of the Red Sea,” he said.

Studying the Red Sea

Burto​n Jones, KAUST professor of marine science, head of the Saudi Aramco-KAUST Marine Environmental Research Center and Zarokanellos’ Ph.D. supervisor, noted “we want to be able to watch the oceans continuously, but this is difficult because we can’t leave a crew out on a ship for months at a time. We can, however, leave the gliders—small robotic submarines about 2 meters long—in the oceans for long periods of time, giving us a continuous presence there. Watching conditions continuously in both space and time presents a tremendous advantage for us.”

Zarokanellos uses the gliders to study the mesoscale eddies of the central Red Sea, focusing on the area of water between KAUST and the Saudi city of Yanbu. Through this work, he and the team in Jones’ Integrated Ocean Processes (IOP) lab learn more about how the eddies, or circular currents of water, drive the biology of the region. Zarokanellos also uses glider data to examine the seasonal intrusion of the Gulf of Aden water and how the eddies contribute to the horizontal distribution of this less salty and high-nutrient water mass, which is one of the main sources of nutrients in Red Sea.

Eddies in 3-D

“The central Red Sea is characterized by high mesoscale eddy activity, and we monitor eddies located in this area that have a diameter from a few kilometers to 200 kilometers,” explained Zarokanellos. “With our gliders, we are able to understand and capture these eddies in 3-D—not only how big they are horizontally, but also at the vertical scale.”

The gliders are equipped with an array of sensors that capture conductivity (salinity), temperature, pressure, chlorophyll, colored dissolved organic matter, backscatter and oxygen. Once in the water, each glider makes a dive to a programmed level approximately every 4 hours, measuring these parameters.

Upon returning to the surface, the glider sends the information it has obtained to a satellite, which then transmits this information back to the team back at KAUST. Zarokanellos and his colleagues complement the gathered data with satellite imagery and information acquired from ship-based hydrographic stations located in the Red Sea.

1,000 dives

In late November of 2015, the KAUST glider operating on what the IOP team calls the “Yanbu line” extending from KAUST to the middle of the Red Sea to Yanbu completed more than 1,000 dives, staying out in the water for 145 days and covering more than 4,500 kilometers of the Red Sea. Team members recovered the glider from the Red Sea on November 22, bringing it back to KAUST on the same day.

“The 1,000th dive of the Yanbu glider is quite a benchmark,” noted Jones. “Up until 2011, there were only about 1,500 profiles of temperature and salinity in the Red Sea, and all these were obtained by ships. In contrast, the glider obtains data constantly as it undulates from the surface down to about 1,000 meters.

“With help from a second glider we have operating off of the city of Duba on the coast of the northern part of the Red Sea, we’ve obtained almost as many profiles of the Red Sea in a few months as were obtained in 100 years of effort prior to that. This has dramatically transformed the amount of information we have about the Red Sea.”

With the data gathered from the Yanbu line glider, Zarokanellos and the team discovered that not only are quasi-permanent anticyclonic eddies present in the Red Sea, but there are also boundary currents and another type of eddy called a cyclonic eddy occurring there.

“This is something unique, because until recently, researchers believed we had only quasi-permanent anticyclonic eddies there, but with the gliders, we were able to observe in real-time and capture the variability of the system in time and space. Both types of eddies are very important for the environment because they bring nutrients to the upper layer of the ocean, increasing primary productivity,” he said.

 

Collaborations in KAUST

Both Zarokanellos and Jones noted that the gliders project would not be possible without the assistance of a large team of multitalented individuals from all over the University.

“We have the support of the KAUST Coastal and Marine Resources Core Lab (CMOR)​; we have the IT department helping us with the data streaming and the satellite communication; and we have all our colleagues in IOP who work to pilot the gliders collect and process glider data,” explained Zarokanellos.

“The gliders feed their data into a computer infrastructure that we maintain here at the University,” said Jones. “We have our software engineer Sebastian Steinke who makes sure all of the data is processed properly, and then it can be transferred to KAUST Associate Professor Ibrahim Hoteit’s group in Earth Science and Engineering, where can be assimilated into near real-time ocean modelling and forecasting. To get to this point, it has taken all these ‘pieces’ from all over the University to make this work and sustain operating the gliders and collecting data on a continuous basis.”

Jones noted that models produced from glider data are important because they provide short-term forecasts for biological or ecological processes that may contribute to events like algal blooms, coral bleaching and other potentially harmful activities.

“The applications of these near-term models are very important to organizations like Saudi Aramco, one of the major supporters of our research,” he said. “The models can be used for managing port operations, for response to and management of oil spills and for the dispersion of microbial contamination from wastewater discharges.

“The models are also an important resource for planning installations of power plants, desalination and wastewater facilities, and for the design and placement of marine-protected areas. Moreover, they give us much insight into the fundamental processes driving the physical, chemical and biological processes in the ocean.”

More gliders—more information

In the future, Jones’ KAUST team hopes to have three to four of the University’s seven gliders in the water at any given time spatially covering almost the whole of the Red Sea while the others are being serviced and prepared for deployment to replace recovered gliders.

“One of our primary goals is to obtain a year-long time series of observations in three of the four major subdivisions of the Red Sea,” said Jones. “Because access to the Red Sea has historically been very limited, there are still limited long-term observations of the annual cycle of physical, biological and chemical processes. Although the gliders can’t measure all of the variables we’re interested in, their sensors give us data describing key parameters relevant to both the physical and biogeochemical environments of the Red Sea.”

In late February 2016, Zarokanellos took the glider data from the Yanbu line to the 2016 Ocean Sciences Meeting in New Orleans, Louisiana (U.S.), one of the world’s most important conferences for discussing and exchanging ideas in marine science. There, he exhibited a poster entitled “Physical and biological response of mesoscale eddies to wintertime forcing in the north central Red Sea (22˚N-25.5˚N).” He hopes to maintain the Yanbu line glider for one year to better understand the seasonal mesoscale eddy variability during the year.

1000th Dive of the Glider

Transforming our knowledge of the Red Sea

“I think the greatest asset KAUST brings to our glider research is the people—people drawn from across laboratories, academic divisions and support services,” said Jones. “There are excellent people here at KAUST who have poured themselves and their excitement into this project, and this makes it very easy overall to do our work because people are capable and passionate about what they are doing.”

“One of the greatest things about our work is that we’re seeing things happening in the Red Sea that people have not seen before,” he continued. “Processes happening in the regions we’ve been studying are a bit of a surprise to us, and they break some of the dogmas on how the Red Sea works—and that’s part of the excitement. By keeping our gliders out there for a period of time, we can actually see these processes happening and find out how persistent they are and how important they are to the ecosystem. This will transform our understanding of the Red Sea.”

“Oceanography is an expensive research field, so the amazing resources and facilities we have here at KAUST are helping to make our plans a reality,” Zarokanellos said. “We are very lucky because we have all the assets and human power here to do great things.”

-By Caitlin Clark, KAUST News