| Deborah Haber, Brad Hindman and Juri Toomre [Colorado] and Rick Bogart [Stanford] have produced the first comparison of direction and magnitude of subsurface flows at selected depths inferred from ring diagram analysis of 11 hours of data from MDI (above) and the GONG+ Big Bear instrument (below). Independent analyses were performed for a set of thirteen 15-degree regions centered at the Carrington coordinates of the bases of the arrows representing the flows. These results are from 1-Dimension RLS inversions at a depth of 7.1 Mm. The results have shown excellent agreement in the flow maps at depths below 2 Mm, but discrepancies near the surface. These variations are currently thought to arise from the differing optical distortions in the two instruments, which mostly affect the high-l modes that sample just below the surface. |