Global Barotropic Tide Modeling Using Inline Self‐Attraction and Loading in MPAS‐Ocean

Abstract

Tides are an integral and dynamic component of the Earth system. According to the IPCC Special Report for Oceans and Cryosphere in a Changing Climate, "it is very likely that the majority of coastal regions will experience statistically significant changes in tidal amplitudes over the course of the 21st century" (Bindoff et al., 2019). Additionally, the report concluded with "high confidence" that tides are one of several local processes essential to predicting future extreme sea level events (Oppenheimer et al., 2019). Coastal tide gauge records point to changes in tidal amplitudes by as much as 1%-2% per decade (Flick et al., 2003;Müller et al., 2011;Ray, 2006). In some locations, the secular changes in tidal amplitudes are of comparable magnitude to changes in mean sea level (Jay, 2009). There are a number of processes that affect observed tides in a particular region, from long-term Earth system processes (such as tectonic motion) to shorter-term processes which could have impacts over the

Improving Global Barotropic Tides With Sub‐Grid Scale Topography

“…We show amplitude and phase of SSH induced by M 2 tides from the baseline experiment in MOM6 (Figure 3a) and compare modeled SSH fields with observations (Figure 3b). 2022) and 6.8 cm in Barton et al (2022). The SSH error is mostly dominated by tides in the Atlantic basin, possibly related to the strongly resonant tides in the Hudson Bay (Arbic et al, 2007(Arbic et al, , 2009.…”

“…Other SAL schemes (e.g., scalar approximation, reading in observed SAL fields, and iterative method) have been adopted to circumvent the need for a fully inline SAL calculation, but these approaches are either highly inaccurate or not applicable to non‐tidal motions or evolving tides in a changing climate. In recent years, a number of ocean models and earth system ocean component models have begun to compute SAL inline (Barton et al., 2022; Brus et al., 2023; Schindelegger et al., 2018; Shihora et al., 2022; Vinogradova et al., 2015). A similar effort is made in MOM6 and results in this work demonstrate the utility of inline SAL.…”

Storm Surge Modeling as an Application of Local Time‐Stepping in MPAS‐Ocean

“…Historically, MPAS‐O has been used primarily for long‐term (on the order of hundreds of years) climate modeling; such models require a multi‐layered ocean that can resolve both barotropic and baroclinic motions. As such, it is uncommon for MPAS‐O to be run in a single layer configuration and only recently was the ability to compute tidal forcing added to the model (Barton et al., 2022).…”

“…In these equations u is the horizontal velocity, t is the time coordinate, f is the Coriolis parameter, k is the local vertical unit vector, $$K=\frac{\vert \mathbf{u}{\vert }^{2}}{2}$$ is the kinetic energy per unit mass, ρ 0 is the (constant) fluid density, p s is the surface pressure, g is the gravitational constant, η is the sea‐surface height perturbation, η EQ is the sea‐surface height perturbation due to equilibrium tidal forcing (Arbic et al., 2018), β is the self‐attraction and loading coefficient (Accad et al., 1978), $$\frac{\mathcal{C}}{H}$$ is a spatially varying internal tide dissipation coefficient (Jayne & St. Laurent, 2001), χ is a scalar tuning factor optimized for barotropic tides response (Barton et al., 2022). H is the resting depth of the ocean, h is the total ocean thickness such that h = H + η , $${\mathcal{C}}_{\mathrm{D}}$$ is the bottom drag coefficient, $${\mathcal{C}}_{\mathrm{W}}$$ is the wind stress coefficient, and u W is the horizontal wind velocity.…”

Scalable self attraction and loading calculations for unstructured ocean tide models

“…Harmonic analysis was performed for these 5 constituents over a 90 day period beginning 30 days after the start of the simulation, resulting in modeled amplitudes, 𝐴, and phase lags, 𝜑, for each constituent. The model configurations, including topographic wave drag and bottom friction schemes, are the same as those used in Barton et al (2022).…”