Long Island Sound (LIS) is a large and wide macrotidal estuary with distributed river inputs, inc... more Long Island Sound (LIS) is a large and wide macrotidal estuary with distributed river inputs, including the Connecticut River (the largest freshwater source) that flows into the eastern LIS near the mouth. In 2010, shipboard surveys of salinity, temperature, and currents were collected along an across-estuary transect in eastern LIS. Numerical model results are compared to these observations and used to study the spatial and temporal variability of salinity, velocity, and freshwater and salt fluxes over a 4-yr period. For all low wind conditions, observations and model results indicate an outward-flowing, low-salinity wedge on the south side with an inward-flowing, higher-salinity area underneath and to the north. Observations and model results during the low wind surveys indicate that stratification substantially decreases with increased tidal amplitude and decreased river discharge; the velocity field is less variable among surveys. Model analysis indicates strong sensitivities to...
ABSTRACT The FRONT experimental coastal observatory combined near-real time measurements, data te... more ABSTRACT The FRONT experimental coastal observatory combined near-real time measurements, data telemetry technology and a theoretical model to provide now-casts and forecasts of the hydrographic structure and circulation in the approaches to Block Island Sound, an estuarine outflow influenced region of the inner southern New England continental shelf. Satellite observations of surface temperature and ocean color have shown that fronts occur frequently in the region. Simulating the characteristics and positions of these fronts using only a sparse array of instruments is a stringent test of the observatory approach. To deliver in-situ data to the model, we developed and demonstrated a robust underwater acoustic data network for transferring observations from an array of bottom mounted acoustic Doppler current profilers to shore in near real-time. Technology developments overcame the challenges presented by the substantial variability of the sound-speed and bottom topography. A three site CODAR installation and a program of fine and course scale hydrographic surveys provided data with which the observatory performance could be evaluated. The three dimensional model at the core of the observatory assimilated satellite-derived surface temperature distributions and long term average temperature and salinity fields. This approach ensured that the tidal frequency sea level variations were imposed at the open boundaries using a global tide model. Assimilation of in-situ current observations in the interior of the domain substantially improved the characteristics of the simulated sub-tidal current variability. The interaction of the tidal and sub-tidal currents with coarse-scale hydrographic gradients created transient fine scale structures (fronts). The project has resulted in new insights to the physical oceanography of a dynamically complex region of the coastal ocean and in addition provided operational nowcasts and forecasts.
... Hebert 1 , Christopher Kincaid 1 , Michelle Aleszczyk 1 , Josh Kohut 2 1. Graduate School of ... more ... Hebert 1 , Christopher Kincaid 1 , Michelle Aleszczyk 1 , Josh Kohut 2 1. Graduate School of Oceanography, University of Rhode Island, 215 South Ferry Road, Narragansett, RI 02882, USA email: d.ullman@gso.uri.edu, dcodiga@gso.uri.edu, lbdecker@gmail.com, sstach@gso ...
... Hebert 1 , Christopher Kincaid 1 , Michelle Aleszczyk 1 , Josh Kohut 2 1. Graduate School of ... more ... Hebert 1 , Christopher Kincaid 1 , Michelle Aleszczyk 1 , Josh Kohut 2 1. Graduate School of Oceanography, University of Rhode Island, 215 South Ferry Road, Narragansett, RI 02882, USA email: d.ullman@gso.uri.edu, dcodiga@gso.uri.edu, lbdecker@gmail.com, sstach@gso ...
<p>... more <p>With a focus on modelling physical aspects of estuaries covering Rhode Island, USA, the Ocean State Ocean Model (OSOM) has been implemented using the Regional Ocean Modeling System. The estuary includes Narragansett Bay, Mt. Hope Bay, and nearby regions including the shelf circulation from Long Island to Nantucket. Our goal is to find predictability and estuarine time scales in order to build a forecasting system </p><p> </p><p>Perturbed ensemble simulations with altered initial condition parameters (temperature, salinity) are combined with concepts from Information Theory to quantify the predictability of the OSOM forecast system. Predictability provides a theoretical estimate of the potential forecasting capabilities of the model in the form of prediction time scales and enhances readily estimable timescales such as the freshwater/ saline water flushing timescale. The predictability of the OSOM model is around 10-40 days, varying by perturbation parameters and season. Internal variability is low when compared to forced variability for the current resolution of OSOM suggesting modest chaos at this resolution.</p><p> </p><p>Freshwater flushing time scale and total exchange flow was calculated for the OSOM model. The freshwater flushing time scale was found to be ~20 days and varies with the choice of the estuary boundary. The predictability time scales and flushing time scales reveal important dynamics of the tracers involved and elucidate their role in driving the estuary.  </p>
The southern New England coast of the United States is particularly vulnerable to land-falling hu... more The southern New England coast of the United States is particularly vulnerable to land-falling hurricanes because of its east-west orientation. The impact of two major hurricanes on the city of Providence (Rhode Island, USA) during the middle decades of the 20th century spurred the construction of the Fox Point Hurricane Barrier (FPHB) to protect the city from storm surge flooding. Although the Rhode Island/Narragansett Bay area has not experienced a major hurricane for several decades, increased coastal development along with potentially increased hurricane activity associated with climate change motivates an assessment of the impacts of a major hurricane on the region. The ocean/estuary response to an extreme hurricane is simulated using a high-resolution implementation of the ADvanced CIRCulation (ADCIRC) model coupled to the Precipitation-Runoff Modeling System (PRMS). The storm surge response in ADCIRC is first verified with a simulation of a historical hurricane that made land...
The potential of using ADvanced CIRCulation model (ADCIRC) to assess the time incremented progres... more The potential of using ADvanced CIRCulation model (ADCIRC) to assess the time incremented progression of hazard impacts on individual critical facilities has long been recognized but is not well described. As ADCIRC is applied to create granular impact models, the lack of transparency in the methods is problematic. It becomes difficult to evaluate the entire system in situations where modeling integrates different types of data (e.g., hydrodynamic and existing geospatial point data) and involves multiple disciplines and stakeholders. When considering increased interest in combining hydrodynamic models, existing geospatial information, and advanced visualizations it is necessary to increase transparency and identify the pitfalls that arise out of this integration (e.g., the inadequacy of data to support the resolution of proposed outputs). This paper thus describes an all numerical method to accomplish this integration. It provides an overview of the generation of the hydrodynamic mo...
Long Island Sound (LIS) is a large and wide macrotidal estuary with distributed river inputs, inc... more Long Island Sound (LIS) is a large and wide macrotidal estuary with distributed river inputs, including the Connecticut River (the largest freshwater source) that flows into the eastern LIS near the mouth. In 2010, shipboard surveys of salinity, temperature, and currents were collected along an across-estuary transect in eastern LIS. Numerical model results are compared to these observations and used to study the spatial and temporal variability of salinity, velocity, and freshwater and salt fluxes over a 4-yr period. For all low wind conditions, observations and model results indicate an outward-flowing, low-salinity wedge on the south side with an inward-flowing, higher-salinity area underneath and to the north. Observations and model results during the low wind surveys indicate that stratification substantially decreases with increased tidal amplitude and decreased river discharge; the velocity field is less variable among surveys. Model analysis indicates strong sensitivities to...
ABSTRACT The FRONT experimental coastal observatory combined near-real time measurements, data te... more ABSTRACT The FRONT experimental coastal observatory combined near-real time measurements, data telemetry technology and a theoretical model to provide now-casts and forecasts of the hydrographic structure and circulation in the approaches to Block Island Sound, an estuarine outflow influenced region of the inner southern New England continental shelf. Satellite observations of surface temperature and ocean color have shown that fronts occur frequently in the region. Simulating the characteristics and positions of these fronts using only a sparse array of instruments is a stringent test of the observatory approach. To deliver in-situ data to the model, we developed and demonstrated a robust underwater acoustic data network for transferring observations from an array of bottom mounted acoustic Doppler current profilers to shore in near real-time. Technology developments overcame the challenges presented by the substantial variability of the sound-speed and bottom topography. A three site CODAR installation and a program of fine and course scale hydrographic surveys provided data with which the observatory performance could be evaluated. The three dimensional model at the core of the observatory assimilated satellite-derived surface temperature distributions and long term average temperature and salinity fields. This approach ensured that the tidal frequency sea level variations were imposed at the open boundaries using a global tide model. Assimilation of in-situ current observations in the interior of the domain substantially improved the characteristics of the simulated sub-tidal current variability. The interaction of the tidal and sub-tidal currents with coarse-scale hydrographic gradients created transient fine scale structures (fronts). The project has resulted in new insights to the physical oceanography of a dynamically complex region of the coastal ocean and in addition provided operational nowcasts and forecasts.
... Hebert 1 , Christopher Kincaid 1 , Michelle Aleszczyk 1 , Josh Kohut 2 1. Graduate School of ... more ... Hebert 1 , Christopher Kincaid 1 , Michelle Aleszczyk 1 , Josh Kohut 2 1. Graduate School of Oceanography, University of Rhode Island, 215 South Ferry Road, Narragansett, RI 02882, USA email: d.ullman@gso.uri.edu, dcodiga@gso.uri.edu, lbdecker@gmail.com, sstach@gso ...
... Hebert 1 , Christopher Kincaid 1 , Michelle Aleszczyk 1 , Josh Kohut 2 1. Graduate School of ... more ... Hebert 1 , Christopher Kincaid 1 , Michelle Aleszczyk 1 , Josh Kohut 2 1. Graduate School of Oceanography, University of Rhode Island, 215 South Ferry Road, Narragansett, RI 02882, USA email: d.ullman@gso.uri.edu, dcodiga@gso.uri.edu, lbdecker@gmail.com, sstach@gso ...
<p>... more <p>With a focus on modelling physical aspects of estuaries covering Rhode Island, USA, the Ocean State Ocean Model (OSOM) has been implemented using the Regional Ocean Modeling System. The estuary includes Narragansett Bay, Mt. Hope Bay, and nearby regions including the shelf circulation from Long Island to Nantucket. Our goal is to find predictability and estuarine time scales in order to build a forecasting system </p><p> </p><p>Perturbed ensemble simulations with altered initial condition parameters (temperature, salinity) are combined with concepts from Information Theory to quantify the predictability of the OSOM forecast system. Predictability provides a theoretical estimate of the potential forecasting capabilities of the model in the form of prediction time scales and enhances readily estimable timescales such as the freshwater/ saline water flushing timescale. The predictability of the OSOM model is around 10-40 days, varying by perturbation parameters and season. Internal variability is low when compared to forced variability for the current resolution of OSOM suggesting modest chaos at this resolution.</p><p> </p><p>Freshwater flushing time scale and total exchange flow was calculated for the OSOM model. The freshwater flushing time scale was found to be ~20 days and varies with the choice of the estuary boundary. The predictability time scales and flushing time scales reveal important dynamics of the tracers involved and elucidate their role in driving the estuary.  </p>
The southern New England coast of the United States is particularly vulnerable to land-falling hu... more The southern New England coast of the United States is particularly vulnerable to land-falling hurricanes because of its east-west orientation. The impact of two major hurricanes on the city of Providence (Rhode Island, USA) during the middle decades of the 20th century spurred the construction of the Fox Point Hurricane Barrier (FPHB) to protect the city from storm surge flooding. Although the Rhode Island/Narragansett Bay area has not experienced a major hurricane for several decades, increased coastal development along with potentially increased hurricane activity associated with climate change motivates an assessment of the impacts of a major hurricane on the region. The ocean/estuary response to an extreme hurricane is simulated using a high-resolution implementation of the ADvanced CIRCulation (ADCIRC) model coupled to the Precipitation-Runoff Modeling System (PRMS). The storm surge response in ADCIRC is first verified with a simulation of a historical hurricane that made land...
The potential of using ADvanced CIRCulation model (ADCIRC) to assess the time incremented progres... more The potential of using ADvanced CIRCulation model (ADCIRC) to assess the time incremented progression of hazard impacts on individual critical facilities has long been recognized but is not well described. As ADCIRC is applied to create granular impact models, the lack of transparency in the methods is problematic. It becomes difficult to evaluate the entire system in situations where modeling integrates different types of data (e.g., hydrodynamic and existing geospatial point data) and involves multiple disciplines and stakeholders. When considering increased interest in combining hydrodynamic models, existing geospatial information, and advanced visualizations it is necessary to increase transparency and identify the pitfalls that arise out of this integration (e.g., the inadequacy of data to support the resolution of proposed outputs). This paper thus describes an all numerical method to accomplish this integration. It provides an overview of the generation of the hydrodynamic mo...
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