Publication Date:
2023-07-19
Description:
〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉Abstract〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉This study addresses the evolution of global tidal dynamics since the Last Glacial Maximum focusing on the extraction of tidal levels that are vital for the interpretation of geologic sea‐level markers. For this purpose, we employ a truly‐global barotropic ocean tide model which considers the non‐local effect of Self‐Attraction and Loading. A comparison to a global tide gauge data set for modern conditions yields agreement levels of 65%–70%. As the chosen model is data‐unconstrained, and the considered dissipation mechanisms are well understood, it does not have to be re‐tuned for altered paleoceanographic conditions. In agreement with prior studies, we find that changes in bathymetry during glaciation and deglaciation do exert critical control over the modeling results with minor impact by ocean stratification and sea ice friction. Simulations of 4 major partial tides are repeated in time steps of 0.5–1 ka and augmented by 4 additional partial tides estimated via linear admittance. These are then used to derive time series from which the tidal levels are determined and provided as a global data set conforming to the HOLSEA format. The modeling results indicate a strengthened tidal resonance by M〈sub〉2〈/sub〉, but also by O〈sub〉1〈/sub〉, under glacial conditions, in accordance with prior studies. Especially, a number of prominent changes in local resonance conditions are identified, that impact the tidal levels up to several meters difference. Among other regions, resonant features are predicted for the North Atlantic, the South China Sea, and the Arctic Ocean.〈/p〉
Description:
Plain Language Summary: We discuss changes in ocean tides during the last 21,000 years. This time marks the Last Glacial Maximum when large parts of the Earth's surface were covered by ice and the sea level was more than 100 m lower than today. Such a low sea level means that many regions of the Earth became land and the ocean's depth changed markedly. The distribution of land and water dominates changes in the tidal levels like the spring or neap tide. With a tidal computer model recently developed by our group, we determine these tidal levels for different times steps from 21,000 years to today. Tidal levels are important for geologists who want to understand former sea level changes with samples found at ancient shorelines. As many of such samples were deposited at a specific tidal level, our modeled information will help them to relate their height to the mean sea‐level. Of course, our model is not the only one that can estimate such changes, but we discuss the advantages of our recent development over previous tools available.〈/p〉
Description:
Key Points: Evolution of four major partial tides from Last Glacial Maximum until present times.〈/p〉〈/list-item〉
〈list-item〉
〈p xml:lang="en"〉Validation of the employed ocean tide model with present‐day tide gauge data and dissipation rates.〈/p〉〈/list-item〉
〈list-item〉
〈p xml:lang="en"〉Diligent derivation of global tidal levels for the interpretation of sea level indexpoints.〈/p〉〈/list-item〉
〈/list〉
〈/p〉
Description:
Bundesministerium für Bildung und Forschung
http://dx.doi.org/10.13039/501100002347
Description:
Deutsche Forschungsgemeinschaft
http://dx.doi.org/10.13039/501100001659
Keywords:
ddc:551.46
;
ocean tide modeling
;
tidal dissipation
;
tidal levels
;
indicative range
;
sea level index points
;
numerical modeling
Language:
English
Type:
doc-type:article
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