A modeling study of the seasonal variability of the circulation in the Rhode Island Sound

Qianqian Liu, University of Rhode Island

Abstract

The Rhode Island Sound (RIS) and Block Island Sound (BIS) exhibit pronounced seasonal changes in their circulation patterns. The Regional Ocean Modeling System (ROMS), configured both for idealized and realistic experiments, is used to help understand the dynamical impact of tides, wind forcing and river discharge, both independently and cumulatively, on this seasonal variability. ^ Both observations (e.g., Acoustic Doppler Current Profiler (ADCP) surveys between 1998 and July 1999 in Narragansett Bay and RIS) and numerical modeling studies reveal a summer cyclonic circulation (5-15 cm/s) pattern in the RIS that disappears in the winter. We find that this seasonal variability is primarily due to wind fluctuations that modify a strong residual tidal circulation. A data set that includes 23 sea level stations and 19 tidal current stations is first used to verify ROMS ability for modeling the tides. We then run wind-forced experiments to show that an offshore Ekman flow, driven by wintertime northwest winds, is responsible for reducing the summertime cyclonic circulation. ^ The seasonal variability of circulation and stratification in the region is further influenced by the Connecticut River which is the major buoyant discharge entering the Long Island Sound (LIS). This generates a freshwater plume around its outflow, which greatly influences the circulation in the LIS, BIS and southern Long Island (LI) coast. The buoyant outflow generates temperature and salinity fronts south of the BIS and around BI and strengthens the down-shelf current in spring.^

Subject Area

Physical Oceanography

Recommended Citation

Qianqian Liu, "A modeling study of the seasonal variability of the circulation in the Rhode Island Sound" (2011). Dissertations and Master's Theses (Campus Access). Paper AAI1502416.
http://digitalcommons.uri.edu/dissertations/AAI1502416

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