Richard P Signell, Ph.D. (Former Employee)
Science and Products
Filter Total Items: 83
The freshwater transport and dynamics of the western Maine coastal current
Observations in the Gulf of Maine, USA, were used to characterize the freshwater transport, temporal variability and dynamics of the western Maine coastal current. These observations included moored measurements, multiple hydrographic surveys, and drifter releases during April–July of 1993 and 1994. There is a strong seasonal signal in salinity and along-shore velocity of the coastal current, caus
Authors
W.R. Geyer, R. P. Signell, D.A. Fong, Jingyuan Wang, D.M. Anderson, B.A. Keafer
A mechanism for offshore initiation of harmful algal blooms in the coastal Gulf of Maine
A combination of observations and model results suggest a mechanism by which coastal blooms of the toxic dinoflagellate Alexandrium fundyense can be initiated from dormant cysts located in offshore sediments. The mechanism arises from the joint effects of organism behavior and the wind-driven response of a surface-trapped plume of fresh water originating from riverine sources. During upwelling-fav
Authors
D.J. McGillicuddy, R. P. Signell, C.A. Stock, B.A. Keafer, M.D. Keller, R.D. Hetland, D.M. Anderson
CMGTooL user's manual
During the past several years, the sediment transport group in the Coastal and Marine Geology Program (CMGP) of the U. S. Geological Survey has made major revisions to its methodology of processing, analyzing, and maintaining the variety of oceanographic time-series data. First, CMGP completed the transition of the its oceanographic time-series database to a self-documenting NetCDF (Rew et al., 19
Authors
Jingping Xu, Fran Lightsom, Marlene A. Noble, Charles Denham
Report of the Community sediment transport modeling workshop
No abstract available.
Authors
Christopher R. Sherwood, Richard P. Signell, Courtney K. Harris
Workshop discusses community models for coastal sediment transport
Numerical models of coastal sediment transport are increasingly used to address problems ranging from remediation of contaminated sediments, to siting of sewage outfalls and disposal sites, to evaluating impacts of coastal development. They are also used as a test bed for sediment-transport algorithms, to provide realistic settings for biological and geochemical models, and for a variety of other
Authors
Christopher R. Sherwood, Richard P. Signell, Courtney K. Harris, Bradford Butman
Predicting the physical effects of relocating Boston's sewage outfall
Boston is scheduled to cease discharge of sewage effluent in Boston Harbor in Spring 2000 and begin discharge at a site 14 km offshore in Massachusetts Bay in a water depth of about 30 m. The effects of this outfall relocation on effluent dilution, salinity and circulation are predicted with a three-dimensional hydrodynamic model. The simulations predict that the new bay outfall will greatly decre
Authors
R. P. Signell, H. L. Jenter, A.F. Blumberg
Bottom currents and sediment transport in Long Island Sound: A modeling study
A high resolution (300-400 m grid spacing), process oriented modeling study was undertaken to elucidate the physical processes affecting the characteristics and distribution of sea-floor sedimentary environments in Long Island Sound. Simulations using idealized forcing and high-resolution bathymetry were performed using a three-dimensional circulation model ECOM (Blumberg and Mellor, 1987) and a s
Authors
R. P. Signell, J. H. List, A.S. Farris
Modeling surface trapped river plumes: A sensitivity study
To better understand the requirements for realistic regional simulation of river plumes in the Gulf of Maine, we test the sensitivity of the Blumberg-Mellor hydrodynamic model to choice of advection scheme, grid resolution, and wind, using idealized geometry and forcing. The test case discharges 1500 m3/s of fresh water into a uniform 32 psu ocean along a straight shelf at 43?? north. The water de
Authors
Jason Hyatt, Richard P. Signell
Modeling sand bank formation around tidal headlands
Sandbanks are often found in the vicinity of coastal headlands around which tidal flows are strong enough to generate significant tidally-forced residual eddies, typically with scales of 2-10 km. One popular hypothesis is that these sandbanks are generated by a 'tidal stirring' mechanism in which the inward-directed pressure gradient associated with these residual eddies produces an inward-directe
Authors
Richard P. Signell, Courtney K. Harris
Circulation and sediment transport in the vicinity of the Hudson Shelf Valley
Sediment transport in the Hudson Shelf Valley and on the adjacent Long Island Shelf are evaluated using available data along with a three-dimensional wind-driven circulation model and a one-dimensional sediment transport model. Winds from the northwest drive currents up the Hudson Shelf Valley, while winds from the east produce weaker currents directed down the valley. Consistent with previous stu
Authors
Courtney K. Harris, Richard P. Signell
Construction of digital bathymetry for the Gulf of Maine
No abstract available.
Authors
Ed T. Roworth, Rich P. Signell
Seafloor environments in the Long Island Sound estuarine system
Four categories of modern seafloor sedimentary environments have been identified and mapped across the large, glaciated, topographically complex Long Island Sound estuary by means of an extensive regional set of sidescan sonographs, bottom samples, and video-camera observations and supplemental marine-geologic and modeled physical-oceanographic data. (1) Environments of erosion or nondeposition co
Authors
H.J. Knebel, R. P. Signell, R.R. Rendigs, L.J. Poppe, J. H. List
Science and Products
Filter Total Items: 83
The freshwater transport and dynamics of the western Maine coastal current
Observations in the Gulf of Maine, USA, were used to characterize the freshwater transport, temporal variability and dynamics of the western Maine coastal current. These observations included moored measurements, multiple hydrographic surveys, and drifter releases during April–July of 1993 and 1994. There is a strong seasonal signal in salinity and along-shore velocity of the coastal current, caus
Authors
W.R. Geyer, R. P. Signell, D.A. Fong, Jingyuan Wang, D.M. Anderson, B.A. Keafer
A mechanism for offshore initiation of harmful algal blooms in the coastal Gulf of Maine
A combination of observations and model results suggest a mechanism by which coastal blooms of the toxic dinoflagellate Alexandrium fundyense can be initiated from dormant cysts located in offshore sediments. The mechanism arises from the joint effects of organism behavior and the wind-driven response of a surface-trapped plume of fresh water originating from riverine sources. During upwelling-fav
Authors
D.J. McGillicuddy, R. P. Signell, C.A. Stock, B.A. Keafer, M.D. Keller, R.D. Hetland, D.M. Anderson
CMGTooL user's manual
During the past several years, the sediment transport group in the Coastal and Marine Geology Program (CMGP) of the U. S. Geological Survey has made major revisions to its methodology of processing, analyzing, and maintaining the variety of oceanographic time-series data. First, CMGP completed the transition of the its oceanographic time-series database to a self-documenting NetCDF (Rew et al., 19
Authors
Jingping Xu, Fran Lightsom, Marlene A. Noble, Charles Denham
Report of the Community sediment transport modeling workshop
No abstract available.
Authors
Christopher R. Sherwood, Richard P. Signell, Courtney K. Harris
Workshop discusses community models for coastal sediment transport
Numerical models of coastal sediment transport are increasingly used to address problems ranging from remediation of contaminated sediments, to siting of sewage outfalls and disposal sites, to evaluating impacts of coastal development. They are also used as a test bed for sediment-transport algorithms, to provide realistic settings for biological and geochemical models, and for a variety of other
Authors
Christopher R. Sherwood, Richard P. Signell, Courtney K. Harris, Bradford Butman
Predicting the physical effects of relocating Boston's sewage outfall
Boston is scheduled to cease discharge of sewage effluent in Boston Harbor in Spring 2000 and begin discharge at a site 14 km offshore in Massachusetts Bay in a water depth of about 30 m. The effects of this outfall relocation on effluent dilution, salinity and circulation are predicted with a three-dimensional hydrodynamic model. The simulations predict that the new bay outfall will greatly decre
Authors
R. P. Signell, H. L. Jenter, A.F. Blumberg
Bottom currents and sediment transport in Long Island Sound: A modeling study
A high resolution (300-400 m grid spacing), process oriented modeling study was undertaken to elucidate the physical processes affecting the characteristics and distribution of sea-floor sedimentary environments in Long Island Sound. Simulations using idealized forcing and high-resolution bathymetry were performed using a three-dimensional circulation model ECOM (Blumberg and Mellor, 1987) and a s
Authors
R. P. Signell, J. H. List, A.S. Farris
Modeling surface trapped river plumes: A sensitivity study
To better understand the requirements for realistic regional simulation of river plumes in the Gulf of Maine, we test the sensitivity of the Blumberg-Mellor hydrodynamic model to choice of advection scheme, grid resolution, and wind, using idealized geometry and forcing. The test case discharges 1500 m3/s of fresh water into a uniform 32 psu ocean along a straight shelf at 43?? north. The water de
Authors
Jason Hyatt, Richard P. Signell
Modeling sand bank formation around tidal headlands
Sandbanks are often found in the vicinity of coastal headlands around which tidal flows are strong enough to generate significant tidally-forced residual eddies, typically with scales of 2-10 km. One popular hypothesis is that these sandbanks are generated by a 'tidal stirring' mechanism in which the inward-directed pressure gradient associated with these residual eddies produces an inward-directe
Authors
Richard P. Signell, Courtney K. Harris
Circulation and sediment transport in the vicinity of the Hudson Shelf Valley
Sediment transport in the Hudson Shelf Valley and on the adjacent Long Island Shelf are evaluated using available data along with a three-dimensional wind-driven circulation model and a one-dimensional sediment transport model. Winds from the northwest drive currents up the Hudson Shelf Valley, while winds from the east produce weaker currents directed down the valley. Consistent with previous stu
Authors
Courtney K. Harris, Richard P. Signell
Construction of digital bathymetry for the Gulf of Maine
No abstract available.
Authors
Ed T. Roworth, Rich P. Signell
Seafloor environments in the Long Island Sound estuarine system
Four categories of modern seafloor sedimentary environments have been identified and mapped across the large, glaciated, topographically complex Long Island Sound estuary by means of an extensive regional set of sidescan sonographs, bottom samples, and video-camera observations and supplemental marine-geologic and modeled physical-oceanographic data. (1) Environments of erosion or nondeposition co
Authors
H.J. Knebel, R. P. Signell, R.R. Rendigs, L.J. Poppe, J. H. List