This study showcases a global, heterogeneously coupled total water level system wherein salinity and temperature outputs from a coarse-resolution ($\sim$12 km) ocean general circulation model are used to calculate density-driven terms within a global, high-resolution ($\sim$2.5 km) depth-averaged total water level model. We demonstrate that the inclusion of baroclinic forcing in the barotropic model requires careful treatment of the internal wave drag term in order to maintain the fidelity of tidal results from the purely barotropic model. By accurately capturing the internal tide dissipation within the coupled system, the resulting heterogeneously coupled model has deep-ocean tidal errors of 2.27 cm, outperforming global, depth-resolving ocean models in representing global tides. Moreover, global median root mean square errors as compared to observations of total water levels, 30-day sea levels, and non-tidal residuals improve by 1.86, 2.55, and 0.36 cm respectively. The drastic improvement in model performance highlights the importance of including density-driven effects within global hydrodynamic models and will help to improve the results of both hindcasts and forecasts in modeling extreme and nuisance flooding. With only an 11\% increase in computational time as compared to the fully barotropic total water level model, this efficient approach paves the way for high resolution coastal water level and flood models to be used directly alongside climate models, improving operational forecasting of total water levels.

e-Navigation—the digitalization and harmonization of data collection, integration, exchange, presentation, and analysis on board and ashore—is an International Maritime Organization initiative that enhances marine navigation and supports safety of life at sea. As e-Navigation and marine activities continue to grow and become more diverse, data providers and users are also becoming more diverse, and the number of data types and sources and amount of data are increasing. Thus, there is an important need to standardize the data into uniform, usable formats so that 1) navigation systems can easily integrate and seamlessly display the data, and 2) mariners can make effective, accurate, and swift navigation decisions based on those data. Effective international standards are developed in consideration of all stakeholder countries’ needs, with the flexibility to evolve to cater to new user requirements. Following these principles, the International Hydrographic Organization has developed a framework for standardization of maritime data products (the S-100 Universal Hydrographic Data Model)—a “standard for standards.” S-100 serves as the umbrella structure by which all other data products should follow, such as high resolution bathymetry (S-102), water levels (S-104), surface currents (S-111), and weather (S-412). This presentation will provide insight into the development and application of international standards for three maritime data products: S-104, S-111, and S-412. Further, we will provide examples of how a data provider employs the international S-100 standard, via state-of-the-art work at the NOAA/National Ocean Service (NOS)/Office of Coast Survey that is converting in real-time, gridded NOS Operational Forecast System surface current predictions into an S-100/S-111 compliant format. Future work includes developing interoperability standards and testing products to ensure they meet user needs.

The mechanisms and geographic locations of tidal dissipation in barotropic tidal models is examined using a global, unstructured, finite element model. From simulated velocities and depths, the total dissipation within the global model is estimated. This study examines the effect that altering bathymetry can have on global tides. The Ronne ice shelf and Hudson Bay are identified as a highly sensitive region to bathymetric specification. We examine where dissipation occur and find that high boundary layer dissipation regions are very limited in geographic extent while internal tide dissipation regions are more distributed. By varying coefficients used in the parameterizations of both boundary layer and internal tide dissipation, regions that are highly sensitive to perturbations are identified. Particularly sensitive regions are used in a simple optimization technique to improve both global and local tidal results. Bottom friction coefficients are high in energetic flow regions, across the arctic ocean, and across deep ocean island chains such as the Aleutian and Ryuku Islands. Global errors of the best solution in the $M_2$ are 3.10 \si{cm} overall, 1.94 \si{cm} in areas deeper than 1000 \si{m}, and 7.74 \si{cm} in areas shallower than 1000 \si{m}. In addition to improvements in tidal amplitude, the total dissipation is estimated and compared to astronomical estimates. Greater understanding of the geographical distribution of regions which are sensitive to friction allows for a more efficient approach to optimizing tidal models.