Verification of the helioseismology travel-time measurement technique and the inversion procedure for sound speed using artificial data

Journal Article · Thu Apr 10 00:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/785/1/40· OSTI ID:22357178

Parchevsky, K. V.; Zhao, J.; Hartlep, T.

We performed three-dimensional numerical simulations of the solar surface acoustic wave field for the quiet Sun and for three models with different localized sound-speed perturbations in the interior with deep, shallow, and two-layer structures. We used the simulated data generated by two solar acoustics codes that employ the same standard solar model as a background model, but utilize different integration techniques and different models of stochastic wave excitation. Acoustic travel times were measured using a time-distance helioseismology technique, and compared with predictions from ray theory frequently used for helioseismic travel-time inversions. It is found that the measured travel-time shifts agree well with the helioseismic theory for sound-speed perturbations, and for the measurement procedure with and without phase-speed filtering of the oscillation signals. This testing verifies the whole measuring-filtering-inversion procedure for static sound-speed anomalies with small amplitude inside the Sun outside regions of strong magnetic field. It is shown that the phase-speed filtering, frequently used to extract specific wave packets and improve the signal-to-noise ratio, does not introduce significant systematic errors. Results of the sound-speed inversion procedure show good agreement with the perturbation models in all cases. Due to its smoothing nature, the inversion procedure may overestimate sound-speed variations in regions with sharp gradients of the sound-speed profile.

• OSTI ID: 22357178
• Journal Information: Astrophysical Journal, Vol. 785, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
AMPLITUDES
COMPUTERIZED SIMULATION
DISTURBANCES
EXCITATION
FORECASTING
LAYERS
MAGNETIC FIELDS
OSCILLATIONS
PERTURBATION THEORY
SIGNAL-TO-NOISE RATIO
STAR MODELS
STOCHASTIC PROCESSES
SUN
SUNSPOTS
SURFACES
THREE-DIMENSIONAL CALCULATIONS
TIME MEASUREMENT
VELOCITY
WAVE PACKETS