The concept of multiple coherence is generalized to study the association between two sets of time series. "Intergroup coherence" is introduced as a measure of the linear relationship between the time histories at a collection of points and the time histories at a different collection of points. This theory is applied to a spectral analysis of marigrams from Canton Island.
Miyata, Motoyasu. 1970. "Complex generalization of canonical correlation and its application to a sea-level study." Journal of Marine Research 28, (2). https://elischolar.library.yale.edu/journal_of_marine_research/1182