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Time-Distance HelioseismologyTime-distance helioseismology is a method of ambient noise imaging using the solar oscillations. The basic realization that led to time-distance helioseismology was that the temporal cross correlation of the signals at two 'surface' (or photospheric) locations should show a feature at the time lag corresponding to the subsurface travel time between the locations. The temporal cross correlation, as a function of the location separation, is the Fourier transform of the spatio-temporal power spectrum of the solar oscillations, a commonly used function in helioseismology. It is therefore likely the characteristic ridge structure of the correlation function had been seen before without appreciation of its significance. Travel times are measured from the cross correlations. The times are sensitive to a number of important subsurface solar phenomena. These include sound speed variations, flows, and magnetic fields. There has been much interesting progress in the 17 years since the first paper on this subject (Duvall et al., Nature, 1993, 362, 430-432). This progress will be reviewed in this paper.
Document ID
20110005678
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Duvall, Thomas L., Jr. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 25, 2013
Publication Date
December 13, 2010
Subject Category
Geophysics
Meeting Information
Meeting: 2010 American Geophysical Union (AGU) Fall Meeting
Location: San Francisco, CA
Country: United States
Start Date: December 13, 2010
End Date: December 17, 2010
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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