GIANT SWIRLS ON THE SUN
A team of scientists led by the Max Planck Institute for Solar System Research and the University of Göttingen has discovered planetary waves of vorticity on and inside the sun that are similar to those that significantly influence weather on earth.
Rossby waves are a natural phenomenon in the earth’s atmosphere and oceans that form in response to the rotation of the planet. They propagate in the direction opposite to rotation and have lifetimes of several months. For forty years, scientists have speculated about the existence of such waves on the sun. Now, they have been unambiguously detected and characterized for the first time“There’s no doubt what we’re seeing are Rossby waves due to the measured, textbook relationship between frequency and wavelength.” said Laurent Gizon, co-principal investigator
at the center for space science at New York University, Abu Dhabi (NYUAD) who was one of the team of scientists involved in the study. The waves are gigantic in size with wavelengths comparable to the solar radius. They are an essential component of the sun’s internal dynamics because they contribute half of the sun’s large-scale kinetic energy.
“That these waves are so big and are only seen in the equatorial regions of the sun is completely unexpected,” Gizon said. In almost every weather map of the earth’s northern hemisphere atmospheric Rossby waves are a prominent feature. They appear as meanders in the jet stream separating cold polar air in the north from warmer subtropical air farther to the south. Sometimes these waves reach the equatorial regions and can even affect weather in Australia. In principle, waves of this type (often referred to as planetary waves) arise on every rotating sphere due to the Coriolis force. Saturn’s hexagon, a stable cloud pattern at the planet’s north pole, may also be an expression of these waves. The team’s findings were reported in the journal “Nature Astronomy.”
