Six-dimensional model for space weather forecasts
Space storms rage between particle showers from the Sun and the Earth’s magnetic field. Professor Minna Palmroth can predict their behaviour better than anyone else.

The Finnish Meteorological Institute in the Dynamicum building studies the weather. Next door, in Physicum, the recently appointed professor of computational space physics, Minna Palmroth, looks beyond earthly weather and the atmosphere to examine space weather.

“Space weather means the barrage of particles coming from the Sun. The Sun is constantly emitting an endless stream of plasma, or charged particles, into space along with light.”

The Earth only receives a fraction of the incoming plasma, as the planet’s magnetic field diverts the stream past us, similarly to a rock diverting the water in a stream. However, satellites and other equipment launched into space swim in the plasma like ships at sea.

And like ships, they are at the mercy of the weather. The rate of the particle shower coming from the Sun varies. As it hits the Earth’s magnetic field, it creates spiral patterns which Palmroth and her team are better at predicting than any other researchers in the world.

What does space weather look like?

The work is based on their model, the Vlasiator, which Palmroth began to develop when everyone else considered it unfeasible.

“When I suggested that we should start six-dimensional modelling of space weather in 2007, people laughed at me,” Palmroth remembers.

Not even the supercomputers of that time would have been able to run a model where millions of particles each have six variables: their location in three-dimensional space as well as the speed and direction of their movement through three-dimensional space.

“But I told them that we should just make the model, and that computers would catch up.”

And they did. When the first version of the space weather model Vlasiator was completed in 2012, supercomputers had sufficient computational capacity to run it. The model has since developed further, but so have computers. This means that the model has increased the researchers’ understanding of the dynamics of space weather.

“When we present our images abroad, researchers often come up to us and ask if this is really what space weather looks like.”

The model is like a satellite network in near space

The model also provides the opportunity to examine the less known phenomena in space weather. One such phenomenon is the magnetotail generated by the magnetic field on the dark side of the Earth, which breaks off every few hours and floats out into space. This is one of the most central issues in space plasma physics.

The dynamics of why the magnetotail breaks have been studied through specific research satellites. Such efforts have been unsuccessful, as the satellite can only provide information on one solitary point in the vastness of space.
Vlasiator helps in this work, as it is equivalent to a network of satellites placed at 300 kilometre intervals throughout near space.

“We already know what Vlasiator thinks about the reasons for why the magnetotail breaks. The answer is brilliant, but I won’t tell you yet,” teases Palmroth.