Jun 01, 2018
Planetary waves similar to those that control weather on Earth discovered on Sun
An international team of scientists, led by Laurent Gizon, co-principal
investigator at the Centre for Space
Science at NYU Abu Dhabi (NYUAD), have
discovered planetary waves of vorticity - a
measure of spin - on and inside the Sun
similar to those that signifcantly inﬂuence
weather on Earth.
Rossby waves are a natural phenomenon
in the atmospheres and oceans of planets
that form in response to the rotation of the
planet. Like Earth, the Sun also rotates and
should support Rossby waves, but their
existence on the Sun was in debate, until
“There’s no doubt what we’re seeing
are Rossby waves due to the measured,
textbook relationship between frequency
and wavelength,” said Gizon.
Solar Rossby waves are gigantic in
size, Gizon explained, 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,” he said.
Astrophysicists from NYUAD, the Max
Planck Institute for Solar System
Research, and Stanford University studied six years of space data, which revealed
the Rossby waves moving in the direction
opposite to the Sun’s rotation.
Rossby waves on the Sun are close
relatives to those known to occur in the
Earth’s atmosphere and oceans, Gizon
said, but are extremely diffcult to detect on
the Sun because they have very small ﬂow
amplitudes, around one meter per second.
“We don’t yet know what role Rossby waves
play in the Sun, but know that they can’t be
ignored in future studies,” said Katepalli
R. Sreenivasan, principal investigator at
NYUAD Center for Space Science.
“Their presence may help us understand
solar convection at the largest spatial
scales, which remains poorly understood.
They are very hard to fnd because of low
signal levels but this research team has
used ingenious data processing techniques
to discover their existence,” added