Coupling of WAVEWATCH III and ADCIRC Using the NUOPC/ESMF Framework

WAVEWATCH III (Tolman et al. 2016) is a major ocean wave modeling system that is widely applied in both operational and research arenas. Initially designed on a global regular grid, in recent years it has been extended to unstructured grids for application in nearshore waters. Similarly, the unstructured-mesh ADvanced CIRCulation (ADCIRC, Luettich et al 1992) model has a wide application both in research and as an operational tide and surge model. Creating a coupling between these two widely-used models, using a community-based coupling infrastructure is therefore a valuable contribution to a wide range of applications. In this study we have coupled these two models using the National Unified Operational Prediction Capability (NUOPC) framework, which in turn is based on the Earth Systems Modeling Framework (ESMF). The primary application for which this has been developed is the Named Storm Event Model (NSEM), which is a high-fidelity, high-accuracy hindcast model designed to provide estimates of wind and waterborne damage due to landfalling hurricanes in compliance with the COASTAL Act of 2012. Within the NUOPC/ESMF framework, each model component is included via an interface called a model cap, which provides the NUOPC driver access to the underlying model variables and model advancing. Such model caps have been developed for ADCIRC (see Moghimi et al. 2017 and for WAVEWATCH III (this study). The model cap for WAVEWATCH III has been based on a new domain decomposition version of the model, which also features the option to use an implicit numerical scheme for coastal application at a high spatial resolution. The new domain decomposition is computationally efficient and scalable to be run on a large number of computational nodes, making it a powerful tool to increase the nearshore resolution and study wave surge interaction in inner shelf regions. This coupled wave-surge model has been validated for idealized laboratory cases as well as a number of major hurricanes, including Ike, Isabel and Sandy. The latter tests were run on the operational HSOFS unstructured mesh featuring 1.8 M nodes, with inundation potential of up to +10 m MSL. The coupled model results showed improvements compared to stand-alone runs and compare well against available observations, showing clear effects on both the wind wave and surge fields in the nearshore and overland regions at landfall via dynamic data exchange between models.

References

Luettich Jr RA, Westerink JJ, Scheffner NW (1992) ADCIRC: An advanced three-dimensional circulation model for shelves, coasts, and estuaries. Report 1. Theory and methodology of adcirc-2ddi and adcirc-3dl. Tech. rep., COASTAL ENGINEERING RESEARCH CENTER VICKSBURG MS

Moghimi et al. (2017) Development of a flexible coupling interface for ADCIRC model for coastal inundation studies, Technical note, NOS, NOAA.

Tolman HL, et al (2016) The WAVEWATCH III development group (ww3dg), 2016: User Manual and system documentation of WAVEWATCH III version 5.16., College Park, MD, USA. NOAA/NWS/NCEP/MMAB Tech. Note 329:326