Speaker
Matthias Rempel
(HAO/NCAR)
Description
We present a series of high-resolution sunspot simulations
that cover a time span of up to 100 hours. The simulation
domain covers the upper 18 Mm of the convection zone and we
use open boundaries that do not maintain the initial field
structure against decay driven by convective motions. We
consider two setups: A sunspot simulation with penumbra, a
"naked-spot" simulation in which we removed the penumbra
after 20 hours through a change in the magnetic top boundary
condition. Both spots are surrounded by a moat flow of a few
100 m/s flow speed in the photosphere extending to about
twice the spot radius and several Mm in depth. The flow
system is more extended for the spot with penumbra. In
addition we find in proximity of both spots a region with
significantly reduced convective flow velocities and
downflow filling factor. Both effects stabilize the spots
against decay, in the case of the spot with penumbra this
leads to an almost stationary solution over the time span
simulated.
