Modeling nearshore storm waves with unstructured implicit WAVEWATCH III in Duck, NC

Accurately modeling nearshore wave transformation during large storms at regional scales is critical for simulating coastal change and estimating flood hazard risks. Recent work has demonstrated that the new, unstructured, implicit WAVEWATCH III (WW3) model can estimate regional wave conditions during hurricanes in depths greater than 10 meters with more accuracy than similar runs with explicit and structured grids due to avoidance of error splitting in the explicit solvers and an improved representation of coastal geometries. In this work, we focus on evaluating the wave action source terms within the model for shallow water physics, including bottom friction, wave breaking, triad interactions, and wave current interactions during Hurricanes and Nor’easters measured at the U.S. Army Engineer Research and Development Center’s Field Research Facility in Duck, NC. Both integral parameters (wave height, period, direction) and energy spectra computed from the model are validated with a cross-shore array of acoustic and pressure gauges in depths ranging from 11- to 2-meters. The results are evaluated with boundary forcing from buoy observations with Neumann type lateral boundaries as well as a full nest into a regional scale grid. Additionally, we also compare results from a full regional unstructured mesh with localized high resolution (~5 meter) at the FRF, which is made possible due to the advances in the scalability of the WW3 code on High Performance Computers using domain decomposition.