Modification of Internal Wave Generation and Energy Conversion in the Nearshore Due To Tide‐Tide and Tide‐Wind Interactions. Issue 4 (5th April 2022)

• Record Type: Journal Article
• Authors: Omidvar, Sorush; Fagundes, Matheus; Woodson, C. Brock
• Is Part Of: Journal of geophysical research. Volume 127:Issue 4(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-04-05
• Subjects: internal waves -- shallow water -- tide and wind; Oceanography -- Periodicals; 551.4605
• DOI: 10.1029/2021JC017986
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: Internal wave generation due to semi‐diurnal tides ( M 2 ) through the acceleration of barotropic tidal flow over sloped topography has received considerable attention over the past several decades. However, the contribution of other tidal constituents and their interactions with M 2 have not been as extensively evaluated. Moreover, on the inner shelf, the cross‐shore wind, which is often neglected in the energy conversion studies, dominates the cross‐shore transport and can also affect the energy conversion process. This study addresses this gap by including a diurnal ( K 1 ) tidal component and a shoreward diurnal sea breeze in an idealized model of southern Monterey Bay as it represents a highly stratified system that experiences active surface and internal tides. Our simulations demonstrate the role of the K 1 tide and its interaction with M 2, which is constructive and insensitive to the initial phase lag. Wind‐induced perturbations grow with the wind speed and enhance M 2 conversion. On the other hand, the wind interaction with the K 1 and M 2 K 1 tides highly depends on the timing with constructive (destructive) conversion occurring when the shoreward wind intensifies during the ebb (flood) tide. Interactions among tides and winds lead to highly variable conversion rates, changes in timing and location of peak conversion, and a range of internal wave frequencies. Such a dynamic alone can be responsible for the complex internal wave environments often observed in the nearshore. Plain Language Summary: Tidal energy is often dissipated in the deep ocean through internal waves (waves that occur beneath the water surface). Internal waves are induced by tidal flow over sloped topography, mainly at the continental shelf break. However, internal wave generation can also occur near shore. In shallow water, tides and sea breezes can affect coastal ocean dynamics, including energy conversion. In this study, we investigate these interactions and the role of environmental parameters such as wind speed, spring‐neap cycle, wind intensification timing and ocean density stratification. We find that nearshore internal wave generation is not likely to be observed as periodic, and the magnitude of energy conversion is variable. Key Points: The linear supper‐position of energy conversion by tides and cross‐shore wind can introduce an error ≥15% on the inner‐shelf region The cross‐shore wind interacts constructively with M 2 and destructively or constructively with M 2 K 1 and K 1 depending on their phasing The linear superposition of conversion by M 2 and K 1 can introduce an error up to 40% for cases with the pycnocline shallower than 17.5 m