Wind-Induced Mixing Processes Under Winter Shamal Conditions in the Northwestern Arabian/Persian Gulf Waters

Abstract This research investigates the impact of air-sea heat fluxes driven by cold and dry Shamal wind events on physical dynamics and vertical mixing processes in the northwestern Arabian/Persian Gulf. The study integrates in situ observations with numerical simulations employing two-equation turbulence models, the k–ε and k–kl formulations. Field measurements were conducted between mid-January and mid-April 2013 at two coastal stations near Qarooh Island, Kuwait. These observations form the initial phase of an extended monitoring effort and include continuous air-sea measurements of water temperature, dissolved oxygen, light penetration, and current profiles, complemented by meteorological data used to drive the numerical models. Turbulence properties including Reynolds stresses, vertical eddy diffusivity, turbulent kinetic energy (TKE), and its dissipation rate were estimated from measurements obtained using a pulse-coherent Acoustic Doppler Current Profiler (ADCP) and subsequently used to evaluate the numerical simulations. Mixing processes were primarily driven by shear instabilities associated with the semi-diurnal tidal currents and convective mixing triggered by Shamal winds, which reached speeds of up to 15 m/s. These observations were compared with simulation outputs using statistical metrics such as mean bias error, root mean square error, Pearson's correlation coefficient, and the Nash–Sutcliffe model efficiency. Both turbulence models demonstrated agreement with the observed turbulence quantities, with correlation values greater than 0.63, demonstrating their effectiveness in reproducing the episodic convective, wind-driven, and tidal mixing dynamics characteristic of this shallow, semi-enclosed marine environment.