Wind-driven exchange flow and inter-basin connectivity in a multi-inlet bay during hurricane and non-hurricane periods

Abstract

This study quantifies wind-induced water volume exchanges through bay-ocean interfaces and among sub-bays of a multiple-inlet estuary, Biscayne Bay in Florida. The bay is elongated and oriented roughly in the north-south direction. Numerical simulations were conducted for both typical and extreme (Hurricane Irma) wind conditions. Results show that wind forcing accounts for 〈 10 % of total volume exchanges during typical winds but for 〉 60 % during hurricane conditions. Further, volume transport through seven inlets and five inter-basin transects is mainly driven by the North wind component (∼ parallel to the orientation of the bay). As a result, the major outflow through inlets is related to Ekman transport driven by southerly (or northward) winds. Except for the fifth inlet, volume transport through all the other six inlets is outward under southerly wind (R²>0.65). In contrast, southward inter-basin transports are mainly driven by northerly (or southward) wind and northward transports by southerly (or northward) wind. Inter-basin volume transport is highly related with the N-S wind (R² >0.74), i.e., the northward/southward transport is in line with the southerly/northerly wind. Additionally, the forcing-response joint Empirical Orthogonal Function (EOF) analysis shows that Biscayne Bay exhibits only one predominant exchange pattern, which explains > 90 % under typical winds and > 80 % during hurricane winds.