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A periodic freshwater patch detachment process from the B lock I sland S ound estuarine plume
Author(s) -
Liu Qianqian,
Rothstein Lewis M.,
Luo Yiyong
Publication year - 2017
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1002/2015jc011546
Subject(s) - estuary , plume , spring (device) , oceanography , stratification (seeds) , discharge , bay , geology , streams , shore , current (fluid) , hydrology (agriculture) , turbulence , tidal current , environmental science , drainage basin , meteorology , geography , physics , seed dormancy , germination , botany , cartography , geotechnical engineering , dormancy , biology , computer network , computer science , thermodynamics
Previous observations suggest periodic freshwater patches separating from the Block Island Sound (BIS) estuarine plume. In this study, the dynamics of the separation process is investigated through a series of numerical experiments using the Regional Ocean Modeling System (ROMS). In addition, we explore the seasonal variability of the freshwater patches and their response to river discharge and ambient current. The model results indicate that episodic freshwater patches are triggered by small changes in tidal currents over the spring‐neap tidal cycle. The spring‐neap variation in tidal currents causes significant, monthly fluctuations in turbulent mixing and vertical stratification in BIS, modulating the freshwater discharge thereby generating episodic freshwater patches that move both downstream along the southern shore of Long Island and toward Rhode Island Sound (RIS). The realistically configured model shows that the freshwater patches experience strong seasonal variability. They are largest in spring when the river discharge peaks, and smallest in summer due to the weak river discharge and a robust upstream ambient current from RIS. According to the analysis of the freshwater transport out of BIS, we conclude that such detachment occurs at tidal mixing fronts.