On the dynamics of the Mouth of the Columbia River: Results from a three‐dimensional fully coupled wave‐current interaction model. Issue 7 (3rd July 2017)

• Record Type: Journal Article
• Authors: Akan, Çiğdem; Moghimi, Saeed; Özkan‐Haller, H. Tuba; Osborne, John; Kurapov, Alexander
• Is Part Of: Journal of geophysical research. Volume 122:Issue 7(2017)
• Page Start: 5218
• Page End: 5236
• Publication Date: 2017-07-03
• Subjects: Columbia River -- wave‐current interaction -- ROMS‐SWAN coupling; Oceanography -- Periodicals; 551.4605
• DOI: 10.1002/2016JC012307
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: Numerical simulations were performed using a 3‐D ocean circulation model (ROMS) two‐way coupled to a phase‐averaged wave propagation model (SWAN), to expand our understanding of the dynamics of wave‐current interactions at the Mouth of the Columbia River (MCR). First, model results are compared with water elevations, currents, temperature, salinity, and wave measurements obtained by the U.S. Army Corp of Engineers during the Mega‐Transect Experiment in 2005. We then discuss the effects of the currents on the waves and vice versa. Results show that wave heights are intensified notably at the entrance of the mouth in the presence of the tidal currents, especially in ebb flows. We also find nonlocal modifications to the wave field because of wave focusing processes that redirect wave energy toward the inlet mouth from adjacent areas, resulting in the presence of a tidal signatures in areas where local currents are weak. The model also suggests significant wave amplification at the edge of the expanding plume in the later stages of ebb, some tens of kilometers offshore of the inlet mouth, with potential implications for navigation safety. The effect of waves on the location of the plume is also analyzed, and results suggest that the plume is shifted in the down‐wave direction when wave effects are considered, and that this shift is more pronounced for larger waves, and consistent with the presence of alongshore advection terms in the salt advection equation, which are related to the Stokes velocities associated with waves. Key Points: Model results show a clear tidal signature in significant wave height at the Mouth of the Columbia River Wave motions modify the location of the plume by hundreds of meters. This effect also feeds back to the wave field, causing subtle but observable further changes Wave effects result in a displacement of the plume in the down‐wave direction