Presenter: Kristin Barton, University of Michigan and Los Alamos National Laboratory

Title: Improving Barotropic Tide Modeling in MPAS-Ocean and Estimating Changes in Future Tides

Abstract:

Modeling the ocean is critical for understanding both present and future risks posed by climate change on coastal communities. Ocean tides in these regions will continue to change over the following decades, yet tides are seldom resolved in climate models. This work seeks to improve barotropic tidal modeling in the Department of Energy’s Model for Prediction Across Scales, or MPAS-Ocean, and to use the resulting tide capabilities to examine potential future changes to tides. When the sea-surface height over a column of ocean moves up and down, this change in mass loading causes small deformations of the Earth’s crust. This deformation, along with changes in the gravitational potential of the deformed Earth and ocean, are known as “self-attraction and loading,” or SAL. We implement an inline SAL calculation using the fast spherical-harmonic transform package and compare the resulting tidal errors to the more common (and computationally cheaper) scalar approximation. We find that using a variable resolution mesh and inline SAL calculations reduce the errors by several centimeters. We further reduce tidal error to 3.3cm through careful selection of parameterized topographic wave drag which occurs as tides flow over the ocean floor, leading to energy dissipation into the baroclinic tide. Finally, using the results of this model development, we examine how tides might look in a future climate by running simulations in MPAS-Ocean with sea-level change, ice-shelf cavity geometry, and landfast ice. We adopt regionally varying sea-level and ice shelves from moderate and extreme future scenarios. The sea-level changes exert the most influence in near-shore regions, while the ice shelves have more impact on the global ocean. However, some near-shore areas see more or comparable impact from ice shelves than sea-level rise, indicating the importance of accounting for cavity geometry in future tide simulations.

Date 07 Dec 2023

Time

PT: 8:30 am
ET: 11:30 am

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Attendees

Time	Title	Presenter	Presentation	Recording	Notes
30 min	Improving Barotropic Tide Modeling in MPAS-Ocean and Estimating Changes in Future Tides	Kristin Barton

Time

Title

Presenter

Presentation

Recording

Notes

30 min

Improving Barotropic Tide Modeling in MPAS-Ocean and Estimating Changes in Future Tides

Kristin Barton