Averaged MDI Dopplergrams show unmistakeable evidence for large-scale velocity features localized to narrow latitude bands. These bands may be evidence of steady zonal flows (torsional oscillation), localized meridional flows (convective rolls), radial flows or lineshifts. There is evidence that they are not continuous across the entire disc, however, indicating that they may be large-scale, but non-axisymmetric flows. They could also be associated with supergranule motions, as they are of comparable scale. I propose to investigate these structures with a view to (a) establishing their nature, i.e. the vector velocity fields or other phenomena responsible for them, (b) intially characterizing their size scale and lifetimes or stability, and (c) their probable effect on estimates of truly axisymmetric velocity structures.
Complete text of proposal.