Signatures of Emerging Subsurface Structures in Acoustic Power Maps

Abstract

We show that under certain conditions, subsurface structures in the solar interior can alter the average acoustic power observed at the photosphere above them. By using numerical simulations of wave propagation, we show that this effect is large enough for it to be potentially used for detecting emerging active regions before they appear on the surface. In our simulations, simplified subsurface structures are modeled as regions with enhanced or reduced acoustic wave speed. We investigate the dependence of the acoustic power above a subsurface region on the sign, depth, and strength of the wave speed perturbation. Observations from the Solar and Heliospheric Observatory/Michelson Doppler Imager (SOHO/MDI) prior and during the emergence of NOAA active region 10488 are used to test the use of acoustic power as a potential precursor of magnetic flux emergence.

7 pages, 5 figures, accepted for publication in Solar Physics on 21 March 2010

References in corpus (4)

• Effect of suppressed excitation on the amplitude distribution of 5-min oscillations in sunspots
• Validating Time-Distance Far-side Imaging of Solar Active Regions through Numerical Simulations
• Time-Distance Solar Far-Side Imaging Using Three-Skip Acoustic Signals
• Imaging the Solar Tachocline by Time-Distance Helioseismology

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• Newly identified properties of surface acoustic power
• Solar wave-field simulation for testing prospects of helioseismic measurements of deep meridional flows
• Verification of the helioseismic Fourier-Legendre analysis for meridional flow measurements
• Helioseismic Holography of an Artificial Submerged Sound Speed Perturbation and Implications for the Detection of Pre-Emergence Signatures of Active Regions
• $f$-mode strengthening from a localized bipolar subsurface magnetic field
• Photospheric Velocity Structures during the Emergence of Small Active Regions on the Sun
• On Strengthening of the Solar f-mode Prior to Active Region Emergence Using the Fourier-Hankel Analysis
• Time-dependent suppression of oscillatory power in evolving solar magnetic fields
• Exploring the Connection between Helioseismic Travel Time Anomalies and the Emergence of Large Active Regions during Solar Cycle 24
• Analysis of Time-Distance Helioseismology for Detection of Emerging Active Regions
• Computing Helioseismic Sensitivity Kernels for the Sun's Large-Scale Internal Flows using Global-Scale Wave-Propagation Simulations