Wind-driven flow dynamics off the Northwestern Arabian Gulf Coast

Abstract

This study investigates the wind-driven hydrodynamics and their influence on the water properties (temperature and salinity) in the Northwestern Arabian/Persian Gulf, off the Kuwaiti Coast. Understanding the effects of wind-driven hydrodynamics on the abrupt changes in water properties and offshore transport is key in determining the fate of the Gulf's environmental sensitive species and distribution of coastal contaminants offshore. Observational meteorological and hydrographical data were collected from mid-October 2013 to mid-January 2014 at two locations. Using time series of the observed water-current profiles, we show that three wind events (order of 2–3 days) with wind directions parallel to the coast generated significant volume transports (1.96 m2/s) in the upper layer directed perpendicular to the coast. The ensuing upwelling/downwelling effects appear to be generally confined to the near coast region (16 km offshore), with cooler waters observed during upwelling and warmer waters during downwelling. Further offshore (Qarooh Island, 44 km offshore) the thermal structure was found to be strongly influenced by a warm ‘tongue’ that extended across the Northern Gulf. The progression and retreat of the ‘tongue’ was found to be in close response to the general wind direction during two wind events. Numerical simulations of the thermal structure at Qarooh, using a one-dimensional model based on the two equation k-ε turbulence model, showed an overall good agreement between the observations and simulations during the three wind events. In particular, the along-shore volume transports which followed the general wind direction were captured well in the simulation. However, the inability of the model to reproduce effects related to the coastal boundary resulted in a poor matching of simulated and observed cross-shore transports.