A Scientist's Life: Janet Sprintall

Physical oceanographer tracks circulation in one of the world’s busiest ocean interchanges

Janet Sprintall is a research oceanographer at Scripps Institution of Oceanography at UC San Diego. She received her bachelor’s degree (with honors) from Griffith University in Queensland, Australia in 1985 and her MSc in 1988 and PhD from the University of Sydney in 1992. She joined Scripps Oceanography in 1993.

explorations now: What do you do for a living?

Janet Sprintall: I'm a seagoing physical oceanographer, which means that I go out to sea and take observations of the way the ocean circulates properties, such as a heat, salinity, and density and the velocity of the ocean. I get to go out on ships to different parts of the ocean all over the world. I'm interested in the role of the ocean in climate variability. My specialty is studying ocean basin exchanges. That is when you have exchanges between one ocean basin and another. That can happen in the Southern Ocean, which goes all the way around Antarctica, so you get exchanges among all the global oceans, or it can happen in Indonesia, for instance, which is the only low latitude exchange of waters from the Pacific Ocean into the Indian Ocean. It's the only place in the world where we have that sort of exchange happening in the equatorial regions so I'm interested in that very much as well.

en: What kinds of instruments do you use in your research?

JS: I usually use moorings, which are upright chains of instruments that can measure velocity (currents) and temperature and salinity. We'll often have two or three of these upright moorings so that we can measure any differences in the currents across different channels and also for redundancy in case of mooring failure. A big part of my job is also using components of the global observing system. And these can include XBTs (expendable bathythermographs) that measure temperature over the upper 900 meters (2,950 feet) of the ocean, Argo floats that profile autonomously and measure temperature and salinity, and satellite measurements of sea surface temperature and sea surface height.


en: What are some of the main questions in your field?

JS: We have a fairly good understanding of the mean circulation through these interfaces and choke points, where ocean properties are exchanged from one basin to another, but we don't have a good understanding of small-scale variability because it's very complicated to measure and there are many eddies and variabilities over different timescales that can impact that exchange. That's one of the big things that we're trying to understand now, by having more sustained measurements in these regions to inform us about these small time- and space-scale variabilities. The Indonesian seas are a region where it’s a nexus of initiation of ENSO (El Niño Southern Oscillation) events, for example. In this region, we have propagation of westerly winds and when those westerly winds hit the western Pacific, they can send big planetary waves of warm water across to the eastern Pacific, which warms, and then that can start a whole El Niño event. This region around Indonesia is important because it affects the climate around the Pacific Ocean and the Indian Ocean as well. It can take heat and freshwater from the Pacific Ocean to the Indian Ocean.

That addition of heat and freshwater changes the properties in the Indian Ocean. The Indian Ocean has warmed the fastest of any ocean basin in recent times. The Indonesian Throughflow, we think, plays a major role in that warming, but we don't have many measurements from within the Indonesian seas to validate that the Pacific Ocean transports heat into the Indian Ocean. We don't fully understand why the Indian Ocean is warming faster than other ocean basins, but we think that the Indonesian Throughflow probably plays a very big role in that warming.

en: Describe some of your current research.

JS: We have MINTIE coming up, which is the “Measuring the Indonesian Throughflow International Experiment.” It’s an international experiment with Indonesia, the U.S., and Australia. We're going to deploy moorings in the Indonesian passages for a three-year period, but we're also going to deploy some Argo-type floats in the internal Indonesian seas. The floats will give us measurements of the temperature and salinity between the inflow and the outflow passages. We can see the changes that happen in the properties from the Pacific to the Indian Ocean. We're looking forward to deploying the moorings probably in mid-2022 and they will be out for three years.

en: What made you want to get into oceanography?

JS: When I was an undergraduate, there was no such thing as taking oceanography as an undergraduate class, so I didn't fully understand that you could even have such a thing as physical oceanography as a discipline. I majored in math and enjoyed it, but I also enjoyed the practical side of math. I wanted to use my math in a way that I could apply it to real problems. Then I remember reading a newspaper article about physical oceanography and seeing an advertisement for a position to study physical oceanography for a masters degree and I thought, wow, that looks good. That looks exactly appropriate. I applied and got the position and went on to do my PhD. And now I think I have the best job in the world. We all say that, but I really believe that.

I grew up in Australia. You learn to swim when you're three or four years old and you just spend your life in the water. Even though I am a mathematician, I very much enjoy going out to sea. There's nothing like being out there and seeing the ocean change right beneath your feet. That's really something special.

en: We’ve written about a cruise in your past that was history-making in the sense of female representation in field research. What is your take on the progress of women in oceanography?

JS: When I first went to sea when I was a PhD student in Australia, it was the first time many of the crew on board had sailed with a woman. I can remember them coming up to me and saying, are you just visiting or are you staying? But now we have quite a strong contingent of women in physical oceanography here at Scripps, which is fairly unusual because physical oceanography is, as you know, a math and physics-based discipline. It's not something that typically attracts many women.

At Scripps, our graduate student intake is also at least 50 percent women in physical oceanography, so I think that's boding well for the future. There are many women I know at Scripps and in my field who lead expeditions and go out to sea regularly and still maintain a family and have managed to work out some sort of life-work balance. We actually have a very strong support network of women oceanographers here at Scripps, and there are also a number of national networks for mentoring women in physical oceanography and I think that's really useful. I’ve been part of the mentoring program MPOWIR (Mentoring Physical Oceanography Women to Increase Retention) for about a decade now. 

Janet Sprintall (fourth from left, standing) and female researchers aboard a 2007 cruise to the Bay of Bengal aboard R/V Roger Revelle
Janet Sprintall (standing, fourth from left) was chief scientist of a 2007 research cruise to the Bay of Bengal in which 15 of 32 members of the science party were women.


en: Why did you want to come to Scripps Oceanography?

JS: It's a preeminent place in the world to study physical oceanography and any oceanography actually. But more than that, I worked in the past in different positions in laboratories and things like that. Even though I've enjoyed that experience and I've enjoyed working with those colleagues and still do work with those colleagues, I missed having interaction with students. I really did find that was the main thing that I enjoyed about coming to Scripps and staying at Scripps. I wanted to have a career here because you get to interact with some of the brightest and best in the world. So yeah, it's a very big positive.

About Scripps Oceanography

Scripps Institution of Oceanography at the University of California San Diego is one of the world’s most important centers for global earth science research and education. In its second century of discovery, Scripps scientists work to understand and protect the planet, and investigate our oceans, Earth, and atmosphere to find solutions to our greatest environmental challenges. Scripps offers unparalleled education and training for the next generation of scientific and environmental leaders through its undergraduate, master’s and doctoral programs. The institution also operates a fleet of four oceanographic research vessels, and is home to Birch Aquarium at Scripps, the public exploration center that welcomes 500,000 visitors each year.

About UC San Diego

At the University of California San Diego, we embrace a culture of exploration and experimentation. Established in 1960, UC San Diego has been shaped by exceptional scholars who aren’t afraid to look deeper, challenge expectations and redefine conventional wisdom. As one of the top 15 research universities in the world, we are driving innovation and change to advance society, propel economic growth and make our world a better place. Learn more at ucsd.edu.

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