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Her first name means “wind” in Estonian. So whenever scientist Tuule Müürsepp would sit in a lecture at the University of Tartu and listen to a professor talk about wind speed or tuulekiirus, she would look up, as if she was being addressed directly. It was only when Tuule moved on to ETH Zürich, a Swiss public research university, that she was able to escape hearing her name.
In Swiss German, wind is just der wind.
Still, the atmospheric and climate sciences seem to follow Tuule anywhere she goes. Even as a teenager growing up in Võrumaa, a heavily forested, rural county in southeast Estonia, she was familiar with radar and weather forecasts, because of her love for nature photography. She needed to know where to go to take the best pictures. “I’m very used to looking at weather maps,” she says. “And that came before I acknowledged that this could become a career path.”
She received her bachelor’s degree from the University of Tartu in physics, chemistry, and material science in 2020, and then moved on to ETH Zürich, where she completed her master’s in atmospheric sciences and meteorology. She will soon complete her PhD in atmospheric dynamics at ETH Zürich. In this program, she is studying how the air moves at a greater scale.
A Young Scientist Abroad
Tuule unveiled some of her PhD research at a conference called Estonian Young Scientists Abroad, that was held in Tallinn at the start of January. The conference was organized and funded by the Estonian Young Academy of Sciences (EYAS), with support from Trigon Capital, a Tallinn-based holding company.
Tuule’s talk was entitled “Single-trajectory analysis: how radiation and clouds contribute to the air transport to the stratosphere.” The troposphere is the lowest layer of the Earth’s atmosphere in direct contact with the Earth’s surface. It’s also the layer of the atmosphere where most meteorological phenomena occur. The stratosphere is the second-lowest layer of the atmosphere, located above the troposphere. Tuule’s research has focused on how radiation and clouds contribute to air extending from the troposphere to the stratosphere. Or, as she describes her work to puzzled relatives back home in Estonia, the part of the atmosphere where planes fly.
“I am looking at clouds at the level where one would fly an airplane,” she says. “I look at how these clouds react to radiation, both solar and radiation emitted from the Earth and how it changes the movement of air.”
She has already made some breakthroughs. Previously in the scientific literature, the idea that radiation might play a role in these processes was merely hypothetical. “We didn’t know how important it was, or how often it occurred,” she says. “Now I already have an answer to that.”
Indeed, radiation plays an important role in temperature changes and movement in the atmosphere.
Radiation also impacts different types of clouds and their layers in different ways. Tuule can use her data to gauge the effects of radiation on high-flying cirrus clouds, those wispy white clouds made up of ice crystals, as well as fluffier, low-drifting cumulus clouds. Both clouds warm at the bottom and cool from the top but higher clouds are considered to have a stronger effect on atmospheric warming, as they radiate at a lower temperature, meaning that they have a greater effect on warming. Understanding these processes could lead not only to advances in basic science, but also impact weather forecasts.
“Clouds are always there, absorbing radiation, heating, emitting and cooling in different parts,” says Tuule. “If we could understand these processes, we could interpret our weather better.”
43 Million Trajectories
Much of the data Tuule uses in her studies is generated by the European Centre for Medium-Range Weather Forecasts, an intergovernmental organization with sites in the UK, Germany, and Italy. The ECMWF provides not only forecasts, but the data behind them. This includes data collected from satellites, weather balloons, aircraft and ground observations. Based on existing data, one can model the weather at any given point in time for which information is available.
“You can replicate the weather yesterday or 10 years ago,” notes Tuule.
Most of the radiation data is pulled from satellite data. This can be used in mathematical models – she usually works in Python. In general, radiation is measured in Watts per square meter, but for her researcher she is studying temperature changes, so the unit of measurement is Kelvins per hour. This is where her background in physics comes into play. “I do the data analysis and use my understanding of physics to understand the processes at work,” she says. “So I ask questions from a physics perspective.”
In her talk at the conference, Tuule showed 43 million trajectories based on 10 years of such data collected from between 2011 and 2020. Eight percent of these movements were dominated by radiative processes, she said.
These discoveries could support further work in the applied sciences in the future, she notes. “To do applied science, you need to understand how things are working right now,” says Tuule.
“You need to have the bases covered, the underlying concepts and everything before you can apply them.”
Staying in Touch
As she completes her PhD, Tuule is drawing her final conclusions and completing the data analyses before publishing. She is also thinking about her own future trajectory, one that will impact not just her own life but Estonian science. It was evident at the conference that while Estonia is proud of its scientists abroad, it also would like to entice them back to do science in the country.
“This is what most Estonian PhD students struggle with in their final year,” related Tuule. “Do I stay or not?” Academia is not the only path, by the way, for someone in the atmospheric sciences. Some go into weather forecasting. Even Ott Tänak, an Estonian rally driver, has a professional meteorologist on his team, she notes.
“I do struggle with it,” Tuule says. “I’m young enough that I don’t need to come back, so I could stay here longer and absorb more, which would be of greater value in the future.”
She also says that Estonian scientists abroad play an important role in introducing the country to colleagues who might have only a cursory knowledge of the country. “People don’t know anything about Estonia until we show up,” says Tuule. “And you can see how hard it is for them to network with Estonian researchers, because they are not even aware that there are people working there in this field.”
Tuule stays in touch with her colleagues at the University of Tartu and when possible collaborates with them. One future area of collaboration could be around how climate change is impacting Estonia. “We don’t really know what the impact is,” she says. But to accomplish such studies will require funding and research. Such a study is at the present moment just an idea. When she is back home, Tuule likes to disappear into the countryside with her camera as always. She takes along her cameras and drones and photographs forests and lighthouses.
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The Estonian Research Council (ETAG) offers various funding opportunities, including the Incoming Postdoctoral Grant, for researchers looking to advance their careers in a dynamic and innovative environment. Read more about different funding opportunities from HERE.
This article is written by Justin Petrone. This article was funded by the European Regional Development Fund through Estonian Research Council.
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