Wind and density driven flow along the Texas-Louisiana continental shelf

Rob Hetland (TAMU), Zhaoru Zhang (TAMU), Xiaoqian Zhang (TAMU), Martino Marta-Almeida (Universidade de Aveiro)

A multi-year numerical simulation of flow and water properties over the Texas-Louisiana is used to investigate weather-band to seasonal variability of wind-driven currents. On shorter timescales, along-shore currents are well correlated with the along-shore wind, with lags of less than six hours in winter, but longer in summer when the shelf is more stratified. Also, the character of the correlation changes in the along-shore direction with a region around Galviston Bay having the lowest relative correlation between winds and currents. On longer timescales, the currents are in a near thermal wind balance, assuming no flow at the sea floor. Seasonal wind patterns are also important in driving the seasonal circulation patterns, indicating that the density field is altered in a way to minimize bottom stress. Interestingly, this also occurs in summer, when the flow is upcoast; strong, retrograde density gradients in the bottom boundary layer are responsible for maintaining the thermal wind balance of the upcoast flow.