HR: 0830h
AN: SP11B-05    [Abstracts]
TI: Sensitivity of time-distance helioseismic measurements to modulation of oscillation amplitudes
AU: * Rajaguru, P
EM: rajaguru@stanford.edu
AF: Stanford University, W.W. Hansen Experimental Physics Lab., Annex A 209, 445 Via Palou, Stanford, CA 94305-4085 United States
AU: Zhao, J
EM: junwei@quake.stanford.edu
AF: Stanford University, W.W. Hansen Experimental Physics Lab., Annex A 209, 445 Via Palou, Stanford, CA 94305-4085 United States
AU: Duvall, T L
EM: tduvall@solar.stanford.edu
AF: NASA Goddard Space Flight Center, Laboratory for Astronomy and Space Physics, Greenbelt, MD 20771 United States
AB: Spatial modulation of oscillation amplitudes in solar active regions arise from several causes, most notably due to the absorption of acoustic waves by sunspots and due to incorrect measurements induced by the changes in the spectral line profiles used in the observations. We show that these modulations may introduce significant changes in the travel times of acoustic waves in addition to those arising directly from the real physical causes. These changes are caused by the convolution of the wave-number spectrum of the modulating function with the power spectra of the oscillations. We develop an empirical 'deconvolution' strategy based on the modulation of oscillation power in each pixel of Dopplergrams and test its effectiveness. These corrections are important in inferring correctly the sub-surface structure and dynamics of localized strong perturbations such as sunspots.
DE: 7522 Helioseismology
DE: 7524 Magnetic fields
SC: Solar Physics Division - AAS [SP]
MN: 2005 Joint Assembly