A Scientist's Life: Luc Lenain

Luc Lenain is an oceanographer and director of the Air-Sea Interaction Laboratory at Scripps Institution of Oceanography at UC San Diego. He received his M.Sc.E. in geophysics and civil engineering from the Université Pierre and Marie Curie, Paris in 2000 and a M.Sc. in physical ocean sciences and engineering from the University of Delaware in 2003. Lenain joined Scripps Oceanography in 2005 as a research and development engineer. He continued to work at Scripps Oceanography during his PhD in physics from the Paris-Saclay University in Cachan, France in 2017.

explorations now (en): What do you do for a living?

Luc Lenain (LL): I try to develop a better understanding of the physical processes that occur when the ocean and the atmosphere interact. This is very important. These processes have a crucial impact on our ability to model climate and the earth system.

en: What are some of the main questions those in your field are trying to answer?

LL: Our ability to parameterize air-sea interactions is of crucial importance to better understand and predict climate so you can predict, for example, the direction climate change is taking us toward.

In that work, one of the big challenges that you're faced with is the fact that you have a very broad range of scales to observe that go anywhere from trying to better understand very small wave-breaking aerosols all the way to very large-scale processes like eddies in the ocean.

With eddies, we know they're very important for biology, for transporting nutrients in various places of the ocean, but we still don't know what their role is when it comes to the interaction between the ocean and the atmosphere. There's a lot of energy exchanged between the ocean and the atmosphere at those scales, but also in the vertical transport into the ocean. These are some of the projects that we've been involved in with NASA in particular, as we try to better physically understand what is going on at those scales.

Another of the questions that I'm interested in is to obtain a better understanding of the life cycle of atmospheric processes above the ocean. For example, we just recently started a new project where we're trying to study the life cycle of fog over the ocean, which is still poorly understood but very important for aviation safety and other applications. There is risk associated with low-flying aircraft in fog conditions so better physical understanding can translate to better predictability of those processes.

en: What are the tools you use in your research?

LL: To develop better understanding of air-sea interaction processes, we use a combination of theory – meaning we try to to develop new mathematics to describe those processes – and observational approaches by collecting data in situ using research vessels, using autonomous vehicles, using aircraft, using satellite, any platform or any instrument we can get our hands on, to better observe the interaction between the ocean and the atmosphere, and numerical simulations.

An autonomous surface vehicle we use in particular is the wave glider. Wave gliders are very well suited to characterize and observe air-sea interactions because they can collect observations really close to the ocean surface on both sides of the interface, in the air and in the water.

We also use drones. Very often we want to collect observations really close to the ocean surface in the atmosphere. We used to do that with research aircrafts, but there is some danger associated with that approach. When you’re flying at an elevation of 100 feet in stormy conditions over the Pacific, for example, this is not a comfortable experience. So we've developed a new technology: miniaturizing a research aircraft and the instrumentation used on large research aircraft that we can deploy onboard drones or on uncrewed aerial vehicles that can fly at very low altitude above the waves.

en: Why did you want to become a scientist?

LL: When I grew up, I was obsessed with earth science and volcanology in particular. I spent a lot of time contacting professors and researchers trying to get into the right direction to be able to make that my job. In the process of doing this, I realized that when you study volcanology in earth science, a lot of it has to do with studying waves propagating in the earth. I grew up in and on the northern coast of France, close to the ocean, so I realized that really my true passion was to have a better understanding of those waves in the ocean.

en: Why did you want to come to Scripps?

LL: I came to Scripps after I met Ken Melville, who was the founder of the Air-Sea Interaction Laboratory here. Ken was a generational scientist who was instrumental in developing a lot of what we know in the field of air-sea interaction. I had the chance to work with him for close to 15 years and learned a tremendous amount from him. Scripps is really one of the leading institutions in the world to do this kind of science. It's also a leading institution to develop new observational capabilities. A large fraction of my research is dedicated to developing new tools, the new robots that collect the information that we need that enable us to do the science that we're after.

The best part of my job is the discovery aspect. I spend every day going into my office trying to develop new technology, to observe all those processes, to analyze those data to develop a better understanding of them.

I'm fortunate to work with a team of engineers and students who are really passionate about air-sea interaction. And it is fun. While we work really hard, very long hours, analyzing data, scratching our heads, trying to figure out what is going on with what we are observing and seeing, spending long hours working through the night during this or that expedition on a research vessel or other locations, we have fun with it, you know? And I think that's a dimension that is really important when you do research.