Helioseismic wavefields are simulated using different meridional-circulation models. Time-distance helioseismic measurements applied on the simulated data indicate that it may be difficult to distinguish between single- or double-cell meridional circulation profiles.
A new method to derive the helioseismic sensitivity kernels for the Sun’s large-scale internal flows is developed. The new method is based on the idea of placing a small-volume flow perturbation inside the Sun’s model, simulating the wavefield in the photosphere, and then measuring the phase shifts caused by this internal perturbation.
The Sun’s poloidal and toroidal magnetic field components derived from synoptic magnetograms are assimilated into a mean-field dynamo model, and activity level for Cycle 25 is predicted based on this approach.
It is demonstrated that when taking into account of the radial inhomogeneity of the Coriolis number, the solar-like differential rotation and the double-cell meridional circulation can both be reproduced by the mean-field model.
Observed seismic upper bounds on large-scale lateral (horizontal) convective-velocity amplitudes in the solar interior at the depth r/R = 0.96 do not agree with modeling results derived at a similar depth from global convection simulations. The observations of low convective-velocity amplitudes throw into question our understanding of thermal and angular momentum transport in the Sun.
Our results show that raising the source surface height 15-30% during solar minimum (depending on the model used) better reproduces the observed IMF open flux from OMNI. We used two different PFSS models and the MDI/HMI magnetograms as input.