** Next:** Application to SOHO/MDI dataset
** Up:** Model of stochastic oscillations
** Previous:** Theoretical comparison between time-distance

The justification for spectral factorization rests upon an assumption
of translational invariance. This assumption runs counter to many
applications of time-distance helioseismology, where the interest
comes in three-dimensional structure.
The assumption of translation invariance may be partly overcome by
working with patches of data with small spatial extent.
Time-distance measurements by crosscorrelation may not seem to have
this perceived disadvantage; however, studies
Kosovichev and Duvall (1997) have shown that significant amounts of
averaging are required to produce signal-to-noise levels high enough
to make reliable measurements. There is an implied assumption of
invariance in this averaging procedure.

** Next:** Application to SOHO/MDI dataset
** Up:** Model of stochastic oscillations
** Previous:** Theoretical comparison between time-distance
Stanford Exploration Project

5/27/2001