On Stratification, Large-Scale Tides, and Temporal Changes in Surface Tidal Elevations: Two-Layer Analytical Model
A. N. Wetzel, B. K. Arbic, I. Cerovecki, M. C. Hendershott, R. H. Karsten, P. D. Miller, and J. F. Molinari
ANW: Graduate Program in Applied and Interdisciplinary Mathematics, University of Michigan
BKA: Department of Earth and Environmental Sciences, University of Michigan
IC and MCH: Physical Oceanography Research Division, Scripps Institution of Oceanography, University of California, San Diego
RHK: Department of Mathematics and Statistics, Acadia University
PDM: Department of Mathematics, University of Michigan
JFM: Department of Mathematics, Florida State University
Abstract:
In this study the influence of stratification on surface tidal elevations in a two-layer analytical model is examined. The model assumes linearized, non-rotating, shallow-water dynamics in one horizontal dimension with astronomical forcing and arbitrary bottom topography. Using a natural separation, both large-scale and small-scale components of the surface tidal elevation are shown to be comparably affected by stratification. It is also demonstrated that the sensitivity of the large-scale surface tide to stratification is significantly affected by the assumed structure of damping and is enhanced by the presence of bottom topography. When bottom topography is present, the model sensitivity is well predicted by the baroclinic wave phase speed. This paper provides a framework to understand how the presence of stratification impacts large-scale as well as small-scale tides, and how, therefore, temporal changes in oceanic stratification can contribute to temporal variations in tides. The analytical model results are qualitiatively consistent with preliminary results from realistic-domain global numerical two-layer tide models.