3 days ago
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Most of us probably don't think much about turbulence until we're being bumped around in an aircraft, but a new study has found something we didn't know before: turbulence at the edges of space, and turbulence in Earth's lower atmosphere, have a lot in common.
When we say space here, we're talking about the thermosphere, about 80-550 kilometers (50-342 miles) above sea level. It's not outer space, but it is where the International Space Station (ISS) and most satellites orbit, and where auroras are formed.
Below that, you've got Earth's lower atmosphere, made up of the troposphere (from the surface to around 12 kilometers or 7.5 miles up) and the stratosphere (which is the layer between the troposphere and the thermosphere.
This new knowledge could give us a better understanding of the environmental systems that circulate around the globe, and improve space and Earth weather forecasts, say the researchers from the University of Rostock in Germany and Kyushu University in Japan.
"This means that both the thermosphere and the troposphere – despite having drastically different atmospheric compositions and dynamics – follow the same physical laws," says meteorologist Huixin Liu, from Kyushu University.
"How the energy flows and dissipates in these two regions is very similar."
To reach these conclusions, the researchers analyzed satellite data from the Challenging Minisatellite Payload (CHAMP) and the Gravity Field and Steady State Ocean Circulation Explorer (GOCE), collected between 2007 and 2009.
The researchers used what are known as third-order structure functions in their analysis – statistical tools that can help spot patterns in winds and turbulence – finding that despite the different conditions in each atmosphere layer, a lot of the 'rules' stayed the same.
What's more, the tendency of the winds to circle in one direction (cyclonic motion) was the same in the thermosphere and the lower atmosphere: counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.
"This suggests that similar underlying large-scale turbulence mechanisms may be at play," write the researchers in their published paper.
There's still a lot we don't understand about near-space atmosphere dynamics, and it's important to fill those gaps in our knowledge: Parts of the atmosphere closer to space are more susceptible to phenomena such as solar storms, and we need to know about any potential dangers ahead of time.
These findings also feed into models of climate change, helping to work out how weather systems might evolve over the coming decades. Now we know that as far as turbulence is concerned at least, shifts in Earth's atmosphere could closely match shifts further out towards space.
"Similar to atmospheric weather forecasting, comprehending the energy distributions in the thermosphere is vital to advance our understanding of space dynamics," says Liu.
"We hope these findings can be used to improve space weather forecasting and ensure the continued functionality and safety of satellite-based technologies essential to everyday life."
The research has been published in Geophysical Research Letters.
