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Title: Time-distance helioseismology of two realistic sunspot simulations

Linear time-distance helioseismic inversions are carried out using several filtering schemes to determine vector flow velocities within two ∼100{sup 2} Mm{sup 2} × 20 Mm realistic magnetohydrodynamic sunspot simulations of 25 hr. One simulation domain contains a model of a full sunspot (i.e., one with both an umbra and penumbra), while the other contains a pore (i.e., a spot without a penumbra). The goal is to test current helioseismic methods using these state-of-the-art simulations of magnetic structures. We find that horizontal flow correlations between inversion and simulation flow maps are reasonably high (∼0.5-0.8) in the upper 3 Mm at distances exceeding 25-30 Mm from spot center, but are substantially lower at smaller distances and larger depths. Inversions of forward-modeled travel times consistently outperform those of our measured travel times in terms of horizontal flow correlations, suggesting that our inability to recover flow structure near these active regions is largely due to the fact that we are unable to accurately measure travel times near strong magnetic features. In many cases the velocity amplitudes from the inversions underestimate those of the simulations by up to 50%, possibly indicating nonlinearity of the forward problem. In every case, we find that our inversions aremore » unable to recover the vertical flow structure of the simulations at any depth.« less
Authors:
;  [1] ;  [2]
  1. Department of Astronomy, New Mexico State University, 1320 Frenger Mall, Las Cruces, NM 88003 (United States)
  2. National Center for Atmospheric Research, HAO Division, 3080 Center Green Drive, Boulder, CO 80301 (United States)
Publication Date:
OSTI Identifier:
22370506
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 794; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLITUDES; CORRELATIONS; DISTANCE; MAPS; NONLINEAR PROBLEMS; OSCILLATIONS; SIMULATION; SUN; SUNSPOTS; VELOCITY