NDLI: Time-distance helioseismology

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Time-distance helioseismology

Content Provider	NASA Technical Reports Server (NTRS)
Author	Duvall Jr., Thomas L.
Copyright Year	2010
Description	Time-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.
File Size	37430
Page Count	1
File Format	PDF
Alternate Webpage(s)	http://archive.org/details/NASA_NTRS_Archive_20110005678
Archival Resource Key	ark:/13960/t3rv5jb9d
Language	English
Publisher Date	2010-12-13
Access Restriction	Open
Subject Keyword	Geophysics Solar Radio Bursts Fourier Transformation Acoustic Velocity Imaging Techniques Solar Prominences Time Lag Helioseismology Solar Activity Noise Sound Cross Correlation Ambience Magnetic Fields Solar Oscillations Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science
Content Type	Text
Resource Type	Article

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