New Swedish satellite to map unstudied winds high up in Earth's atmosphere

​Chalmers University of Technology has won the competition to provide Sweden’s next national research satellite to the Swedish National Space Board. The satellite, named SIW, will be the first to study wind currents in the upper atmosphere, increasing understanding about how they affect weather and climate.

​”I am really happy to see our proposal become a reality”, says Kristell Pérot, researcher in the Division of Microwave and Optical Remote Sensing, at the Department of Space, Earth and Environment at Chalmers.
SIW, which stands for Stratospheric Inferred Winds, will study wind patterns in the atmosphere to answer questions about their dynamics and circulation. It will contribute important data to climate models, and increase understanding of how the different parts of the atmosphere interact.

Better weather forecasting

The climate and weather in the troposphere, the layer closest to Earth’s surface, is affected by wind changes in the two layers above, the stratosphere and the mesosphere (altitudes between 11 and 85 kilometres). Observing and analysing events in the upper layers is therefore critical to achieving more reliable long-term predictions.

For example, many consider the recent cold weather across Europe this month, and concurrent warmer temperatures in the Arctic, to be linked to temperature changes in the upper atmosphere – so-called ’sudden stratospheric warming’.

“This process is not very well understood in current models, and more knowledge is needed. With SIW, it will be easier to study this kind of event and to understand the forces behind them. That has never been done in this way before” says Kristell Pérot.


“SIW will also be a fine complement to the satellite Aeolus, to be launched by the European Space Agency later this year to study the winds lower down in the atmosphere,” she adds.

Dual purpose

Patrick Eriksson, professor of Global Environmental Measurements at Chalmers, believes the second part of SIW’s mission will be equally important – to measure the concentration of certain gases in the atmosphere.

”As it stands, SIW looks to be alone in being able to measuring the gases that are important to assessing the status of the ozone layer. Above all, it’s chlorine- and nitrogen-bearing gases that we want to keep track of. SIW will take over that role after the satellite Odin, which will soon be ready for retirement after 17 years in space” says Eriksson.

Several Swedish companies will participate in the SIW project, including Omnisys Instruments, which will be responsible for the scientific instruments, and OHB Sweden, which will construct the satellite itself and have overall responsibility for the project. Donal Murtagh, professor of Global Environmental Measurements and Head of Division Microwave and Optical Remote Sensing at the Department of Space, Earth and Environment, will be scientifically responsible for SIW. The satellite will also contain parts manufactured at the Department of Microtechnology and Nanoscience – MC2 – at Chalmers.

The Swedish National Space Board will finance the production and launch of SIW, which will be the second satellite in its innovative research satellites venture. It is scheduled for launch in 2022.

You can read more about the SIW satellite on the Swedish National Space Board’s website (Swedish only).

Patrick Eriksson
  • Full Professor, Geoscience and Remote Sensing, Space, Earth and Environment