Richard P Signell, Ph.D. (Former Employee)

A three-dimensional hydrodynamic model was developed as part of a cooperative U.S. Geological Survey/Massachusetts Water Resources Authority program to study contaminated sediment accumulation and transport in Massachusetts Bay. This report details the development of the model and assesses how well the model represents observed currents and water properties in the bay. It also summarizes...

Massachusetts and Cape Cod Bays form a semienclosed coastal basin that opens onto the much larger Gulf of Maine. Subtidal circulation in the bay is driven by local winds and remotely driven flows from the gulf. The local-wind forced flow is estimated with a regional shallow water model driven by wind measurements. The model uses a gravity wave radiation condition along the open-ocean...

No abstract available.

An 18 month simulation of circulation was conducted in Massachusetts Bay, a roughly 35 m deep, 100??50 km embayment on the northeastern shelf of the United States. Using a variant of the Blumberg-Mellor (1987) model, it was found that a continuous 18 month run was only possible if the velocity field was Shapiro filtered to remove two grid length energy that developed along the open...

A time-dependent, three-dimensional numerical modeling study of the tides of Massachusetts and Cape Code Bays, motivated by construction of a new sewage treatment plant and ocean outfall for the city of Boston, has been undertaken by the authors. The numerical model being used is a hybrid version of the Blumberg and Mellor ECOM3D model, modified to include a semi-implicit time-stepping...

This physical oceanographic study of the Massachusetts Bays (fig. 1) was designed to provide for the first time a bay-wide description of the circulation and mixing processes on a seasonal basis. Most of the measurements were conducted between April 1990 and June 1991 and consisted of moored observations to study the current flow patterns (fig. 2), hydrographic surveys to document the...

Tidal dispersion and the horizontal exchange of water between Boston Harbor and the surrounding ocean are examined with a high-resolution (200 m) depth-averaged numerical model. The strongly varying bathymetry and coastline geometry of the harbor generate complex spatial patterns in the modeled tidal currents which are verified by shipboard acoustic Doppler surveys. Lagrangian exchange...

The role of tidal dispersion is reassessed, based on a consideration of the relevant physical mechanisms, particularly those elucidated by numerical simulations of tide-induced dispersion. It appears that the principal influence of tidal currents on dispersion occurs at length scales of the tidal excursion and smaller; thus the effectiveness of tidal dispersion depends on the relative...

Unidata's network Common Data Form, netCDF, provides users with an efficient set of software for scientific-data-storage, retrieval, and manipulation. The netCDF file format is machine-independent, direct-access, self-describing, and in the public domain, thereby alleviating many problems associated with accessing output from large hydrodynamic models. NetCDF has programming interfaces...

The flushing of Boston Harbor, a shallow, tidally dominated embayment with little fresh water input, is investigated using a depth-averaged model. The modeled tidal currents exhibit strong spatial variability and ebb/flood asymmetry due to complex topography and coastline geometry and were verified by shipboard acoustic Doppler current profiler measurements. At the inlets to the harbor...

The U.S. Geological Survey (USGS) is conducting studies in Boston Harbor, Massachusetts Bay, and Cape Cod Bay designed to define the geologic framework of the region and to understand the transport and accumulation of contaminated sediments. The region is being studied because of environmental problems caused by the introduction of wastes for a long time, because a new ocean outfall (to...

Eddies with length scales of 1-10 km are commonly observed in coastal waters and play an important role in the dispersion of water-borne materials. The generation and evolution of these eddies by oscillatory tidal flow around coastal headlands is investigated with analytical and numerical models. Using shallow water depth-averaged vorticity dynamics, eddies are shown to form when flow...