Abstract


  SURFACE EFFECTS IN HELIOSIESMOLOGY

  P. Rajaguru, Indian Institute of Astrophysics, rajaguru@iiap.res.in

A host of physical and analysis issues due to a complex interplay of radiative transfer, line formation physics, and atmospheric wave evolution, all mediated by magnetohydrodynamics of the near surface layers, make existing helioseismic analyses, especially the time-distance anslyses, highly inadequate. The center-to-limb systematics in travel times and its influence in recent measurements of meridional flow is one example. I will present several other examples where the above listed 'surface' effects dominate, and discuss possible observational avenues based on imaging spectroscopy (and spectropolarimetry) that can provide partial remedies. I will also discuss how such observational analyses help in understanding the MHD wave modes in the atmosphere driven by interior p modes.