Analysis of turbulence characteristics in a nearshore area beyond the surf zone of a mesotidal bay

Turbulence impacts renewable energy converters’ performance due to differences in turbulent kinetic energy (TKE) production and TKE dissipation in estuarine, coastal, and shelf regions. However, the turbulence structure under different environmental forcings is not well understood. This study uses waves, tides, and wind data to analyse the mean flow field and turbulence characteristics in Todos Santos Bay (TSB), a mesotidal bay in the northern Mexican Pacific. The main results are based on a month-long time series obtained with a Sentinel V50, a five-beam Acoustic Doppler Current Profiler (ADCP), installed in a location within the bay where currents are less than 0.55 m s −1 . A tidal decomposition analysis of sea level and current data confirmed mixed and predominantly semi-diurnal tides. Waves and wind stresses affect the flow in the layers near the sea surface. We computed the Reynolds stresses, TKE, anisotropy, TKE production and TKE dissipation to characterize the turbulence properties. The zonal vertical Reynolds stress increases from the bottom upwards, while the meridional vertical Reynolds stress decreases from the bottom upwards. The turbulent kinetic energy increases from the bottom upwards. The waves do not significantly affect the Reynolds stresses, the TKE, or the anisotropy ratio when the significant wave height is less than 0.7 m. It is worth highlighting that strong wave conditions have an important effect on the turbulence characteristics of the site, even during spring tides. In addition, turbulent processes change with time following flood and ebb tides in the bay, and the TKE and the zonal vertical Reynolds stress are higher during neap tides than during spring tides. Finally, TKE budget computations showed that TKE dissipation dominates over TKE production, implying the existence of non-local transport to the TKE budget at the site; these turbulence metrics are enhanced during neap tides. • Turbulence vertical structure relates to Reynolds stresses and TKE. • Waves alter turbulence structure when wave height exceeds 0.7 m. • Zonal stress and TKE rise bottom-to-surface; meridional stress rises opposite. • Neap tides with strong waves intensify turbulent processes. • TKE budget shows dissipation dominates over production.