Are granules good tracers of solar surface velocity fields?

• Using a numerical simulation of compressible convection with radiativetransfer mimicking the solar photosphere, we compare the velocity fieldderived from granule motions to the actual velocity field of the plasma.We thus test the idea that granules may be used to trace large-scalevelocity fields at the sun's surface. Our results show that this isindeed the case provided the scale separation is sufficient. We thusestimate that neither velocity fields at scales less than 2500 km nortime evolution at scales shorter than 0.5 hr can be faithfully describedby granules. At larger scales the granular motions correlate linearlywith the underlying fluid motions with a slope of ≲2 reachingcorrelation coefficients up to ~ 0.9.

Subject headings

NATURVETENSKAP  -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)

Keyword

CONVECTION

SUN: GRANULATION

SUN: PHOTOSPHERE

Publication and Content Type

art (subject category)

ref (subject category)