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Modes and emergent time scales of embayed beach dynamics
Author(s) -
Ratliff Katherine M.,
Murray A. Brad
Publication year - 2014
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl061680
Subject(s) - shore , geology , scaling , forcing (mathematics) , oceanography , geodesy , climatology , geometry , mathematics
In this study, we use a simple numerical model (the Coastline Evolution Model) to explore alongshore transport‐driven shoreline dynamics within generalized embayed beaches (neglecting cross‐shore effects). Using principal component analysis (PCA), we identify two primary orthogonal modes of shoreline behavior that describe shoreline variation about its unchanging mean position: the rotation mode, which has been previously identified and describes changes in the mean shoreline orientation, and a newly identified breathing mode, which represents changes in shoreline curvature. Wavelet analysis of the PCA mode time series reveals characteristic time scales of these modes (typically years to decades) that emerge within even a statistically constant white‐noise wave climate (without changes in external forcing), suggesting that these time scales can arise from internal system dynamics. The time scales of both modes increase linearly with shoreface depth, suggesting that the embayed beach sediment transport dynamics exhibit a diffusive scaling.