Validation of 3D helioseismic inversions of travel-times through simulations of artificial data with the correct noise statistics

In time-distance helioseismology most inversion procedures ignore the correlations in the data errors, which may be large as shown by Gizon & Birch (2004). Here we simulate the travel-time perturbations that result from a known distribution of sound-speed inhomogeneities (simulating sunspot-like structures) using wave-based sensitivity kernels. A realistic stochastic noise component is added to the data. We then apply a 3D inversion procedure that takes into account the full covariance matrix of the simulated data. The validation of the inversion is achieved through comparison of the inferred soundspeed distribution with the exact solution.