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The rainmaker?

Heta Koski

There aren't many people in the world that could be described as a rainmaker quite as literally as Hannele Korhonen. Korhonen, a research professor at the Finnish Meteorological Institute, is launching a new project whose results could be highly significant in solving water shortages in the world's driest regions. Or at least that's the hope. However, from a researcher's perspective it's not that straightforward, and they are currently seeking scientific evidence from the project.

But let's return to that later and first ask how Korhonen ended up researching the topic:

"It's great to learn new things!" Korhonen's eyes light up.

"I really loved school when I began studying physics at the University of Helsinki – I felt a career in research beckoning me right from the outset."

Korhonen wrote her master's thesis in Markku Kulmala's esteemed international research team and continued with her doctoral thesis. After working at the Finnish Meteorological Institute for a few years, Korhonen headed abroad. While working at Leeds University, she reinforced her professional identity as a researcher and boosted her self-confidence.

World-class science

Korhonen had picked up an ambitious attitude from Kulmala's team: let's do world-class science.

"Internalising that approach has helped my career a lot. Healthy self-confidence has driven me boldly onward," says Korhonen

And she has indeed been highly successful with this attitude. The project she is currently leading – a joint project between the Finnish Meteorological Institute, University of Helsinki and Tampere University of Technology – is one of three projects that nabbed a 1.5 million dollar grant each from the United Arab Emirates' Research Program for Rain Enhancement Science. Only three per cent of applications went through.


The successful rain researchers and their sponsors at an awards ceremony in Abu Dhabi in January. Photo: UAE Research Program for Rain Enhancement

Another of Korhonen's research teams was previously granted EUR 2 million in highly sought-after European Research Council (ERC) funding. Her current project will run until 2020, developing statistical depictions of the effects of subgrid aerosol-cloud interactions on climate models. This means that Korhonen and her colleagues will be trying to improve the mathematical accuracy of climate models with regard to the behaviour of particles and clouds. Particles and clouds are also involved in rainmaking.

And rain – or the lack thereof – is no small thing globally. According to a UN estimate, three out of four jobs in the world are to some extent dependant on water. And according to the latest estimates, by 2025 two thirds of the world's population will also be living in areas that suffer from at least occasional water shortages. Rain modification has been put forward as one solution for easing water shortages.

"The Emirates uses twenty times more freshwater than they have. This water must therefore be either processed from seawater or artificially produced. They are continually attempting rain modification, and have designated aircraft that fly 150-200 times per year," says Korhonen.

These aircraft seed aerosol particles in clouds with the hope that they will facilitate the formation of raindrops.

In principle, it is very simple to make it rain. Every raindrop inside a cloud forms around a particle. The drops need to grow large enough for gravity to make them fall and thereby cause rain.

If there are a lot of cloud drops, the water inside the cloud will split into many drops and individual drops will not get the chance to grow large enough. The research project led by Korhonen is trying to find out whether certain particles will facilitate the formation of sufficiently large drops.  At least two requirements are already known: the particles must be sufficiently large and also water soluble, so they can bind water to themselves.

But does it work?

Korhonen's work as a rainmaker is only just beginning. The expectations are considerable, but then so are the challenges. Some of them are purely practical: Operational culture in the Emirates is an unknown factor, and the physical environment will also pose its own challenges.

"The conditions are very different to those we're used to in Finland. It's very dry and dusty, and we're uncertain as to how well our measuring devices will work in such conditions."


Conditions in the Emirates are dry and dusty. Photo: Heikki Lihavainen

Modelling itself is far from straightforward. Korhonen's research will combine measurement data with information from three different computational models in a way that has never been done before.

"In the end, maybe the most significant challenge will be proving whether or not seeding particles in clouds really results in something that causes rain. What would have happened if we had done nothing at all? We're still at the ‘if it works' stage," says Korhonen.

Like climate modification in general, weather modification and rain formation also involve ethical questions.  For example, will human-assisted rain in one place be taking rain away from somewhere else? Researchers are not yet able to answer these questions. It could be that artificially created rain would never have rained anywhere else – it would have gradually evaporated into the air instead. Korhonen's team is seeking to study not only opportunities for increasing rain, but also the overall effects of seeding.

Enabling researchers to think big

During a typical working day, research professors and team leaders no longer have the same amount of time for actual research as they used to. Their days are filled with supervisory work, general expert tasks, and applying for funding.

"Naturally I sometimes miss being able to absorb myself in research," says Korhonen.

However, as team leader, she feels she can make more of an impact in helping the team achieve their shared goal.

"It's great to see your team members taking responsibility and developing as researchers. I look on their work almost with a mother's pride," she says, laughing.

Korhonen is also a member of the Computational Science Forum. The Forum provides the Ministry of Education and Culture with perspectives on the future of scientific computing to support the development of national computing and data management infrastructure.

"My role is to highlight the needs of research institutes in particular. At least the significance of computing is definitely not going to decline in the future. Simulations are often more cost-effective than measurements, and not everything can even be studied empirically. Computational methods will also be extended to an increasing number of new scientific fields," says Korhonen.

"Advancements in computing power mean that in many cases there's no longer a critical need for speeding up actual computing time – the issue is storing and managing continually growing volumes of data."

Korhonen says that, from a service user's perspective, these requirements can be encapsulated into three key points: resources must be available, available exactly when required, and available to the extent required. Long-term, ambitious research work can only be planned when you know that the resources you require will still be available in the future.

"If the resources you require are in sight within, say, the next five years, researchers can think big with no need to scale down their ambition."



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