Richard P Signell, Ph.D. (Former Employee)
Science and Products
Filter Total Items: 90
Toxic Alexandrium blooms in the western Gulf of Maine: The plume advection hypothesis revisited Toxic Alexandrium blooms in the western Gulf of Maine: The plume advection hypothesis revisited
The plume advection hypothesis links blooms of the toxic dinoflagellate Alexandrium fundyense in the western Gulf of Maine (GOM) to a buoyant plume derived from river outflows. This hypothesis was examined with cruise and moored-instrument observations in 1993 when levels of paralytic shellfish poisoning (PSP) toxins were high, and in 1994 when toxicity was low. A coupled physical...
Authors
D.M. Anderson, B.A. Keafer, W.R. Geyer, R. P. Signell, T.C. Loder
Structure and variability of the Western Maine Coastal Current Structure and variability of the Western Maine Coastal Current
Analyses of CTD and moored current meter data from 1998 and 2000 reveal a number of mechanisms influencing the flow along the western coast of Maine. On occasions, the Eastern Maine Coastal Current extends into the western Gulf of Maine where it takes the form of a deep (order 100 m deep) and broad (order 20 km wide) southwestward flow with geostrophic velocities exceeding 20 cm s -1...
Authors
J.H. Churchill, N.R. Pettigrew, R. P. Signell
The kinematic and hydrographic structure of the Gulf of Maine Coastal Current The kinematic and hydrographic structure of the Gulf of Maine Coastal Current
The Gulf of Maine Coastal Current (GMCC), which extends from southern Nova Scotia to Cape Cod Massachusetts, was investigated from 1998 to 2001 by means of extensive hydrographic surveys, current meter moorings, tracked drifters, and satellite-derived thermal imagery. The study focused on two principal branches of the GMCC, the Eastern Maine Coastal Current (EMCC) that extends along the...
Authors
N.R. Pettigrew, J.H. Churchill, C.D. Janzen, L.J. Mangum, R. P. Signell, A.C. Thomas, D.W. Townsend, J.P. Wallinga, H. Xue
Sediment dynamics in the Adriatic Sea investigated with coupled models Sediment dynamics in the Adriatic Sea investigated with coupled models
Several large research programs focused on the Adriatic Sea in winter 2002-2003, making it an exciting place for sediment dynamics modelers (Figure 1). Investigations of atmospheric forcing and oceanic response (including wave generation and propagation, water-mass formation, stratification, and circulation), suspended material, bottom boundary layer dynamics, bottom sediment, and small...
Authors
Christopher R. Sherwood, Jeffrey W. Book, Sandro Carniel, Luigi Cavaleri, Jacopo Chiggiato, Himangshu Das, James D. Doyle, Courtney K. Harris, Alan W. Niedoroda, Henry Perkins, Pierre-Marie Poulain, Julie Pullen, Christopher W. Reed, Aniello Russo, Mauro Sclavo, Richard P. Signell, Peter A. Traykovski, John C. Warner
The freshwater transport and dynamics of the western Maine coastal current 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...
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 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...
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 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...
Authors
Jingping Xu, Fran Lightsom, Marlene A. Noble, Charles Denham
Report of the Community sediment transport modeling workshop 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 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...
Authors
Christopher R. Sherwood, Richard P. Signell, Courtney K. Harris, Bradford Butman
Predicting the physical effects of relocating Boston's sewage outfall 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...
Authors
R. P. Signell, H. L. Jenter, A.F. Blumberg
Bottom currents and sediment transport in Long Island Sound: A modeling study 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...
Authors
R. P. Signell, J. H. List, A.S. Farris
Modeling surface trapped river plumes: A sensitivity study 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...
Authors
Jason Hyatt, Richard P. Signell
Science and Products
Filter Total Items: 90
Toxic Alexandrium blooms in the western Gulf of Maine: The plume advection hypothesis revisited Toxic Alexandrium blooms in the western Gulf of Maine: The plume advection hypothesis revisited
The plume advection hypothesis links blooms of the toxic dinoflagellate Alexandrium fundyense in the western Gulf of Maine (GOM) to a buoyant plume derived from river outflows. This hypothesis was examined with cruise and moored-instrument observations in 1993 when levels of paralytic shellfish poisoning (PSP) toxins were high, and in 1994 when toxicity was low. A coupled physical...
Authors
D.M. Anderson, B.A. Keafer, W.R. Geyer, R. P. Signell, T.C. Loder
Structure and variability of the Western Maine Coastal Current Structure and variability of the Western Maine Coastal Current
Analyses of CTD and moored current meter data from 1998 and 2000 reveal a number of mechanisms influencing the flow along the western coast of Maine. On occasions, the Eastern Maine Coastal Current extends into the western Gulf of Maine where it takes the form of a deep (order 100 m deep) and broad (order 20 km wide) southwestward flow with geostrophic velocities exceeding 20 cm s -1...
Authors
J.H. Churchill, N.R. Pettigrew, R. P. Signell
The kinematic and hydrographic structure of the Gulf of Maine Coastal Current The kinematic and hydrographic structure of the Gulf of Maine Coastal Current
The Gulf of Maine Coastal Current (GMCC), which extends from southern Nova Scotia to Cape Cod Massachusetts, was investigated from 1998 to 2001 by means of extensive hydrographic surveys, current meter moorings, tracked drifters, and satellite-derived thermal imagery. The study focused on two principal branches of the GMCC, the Eastern Maine Coastal Current (EMCC) that extends along the...
Authors
N.R. Pettigrew, J.H. Churchill, C.D. Janzen, L.J. Mangum, R. P. Signell, A.C. Thomas, D.W. Townsend, J.P. Wallinga, H. Xue
Sediment dynamics in the Adriatic Sea investigated with coupled models Sediment dynamics in the Adriatic Sea investigated with coupled models
Several large research programs focused on the Adriatic Sea in winter 2002-2003, making it an exciting place for sediment dynamics modelers (Figure 1). Investigations of atmospheric forcing and oceanic response (including wave generation and propagation, water-mass formation, stratification, and circulation), suspended material, bottom boundary layer dynamics, bottom sediment, and small...
Authors
Christopher R. Sherwood, Jeffrey W. Book, Sandro Carniel, Luigi Cavaleri, Jacopo Chiggiato, Himangshu Das, James D. Doyle, Courtney K. Harris, Alan W. Niedoroda, Henry Perkins, Pierre-Marie Poulain, Julie Pullen, Christopher W. Reed, Aniello Russo, Mauro Sclavo, Richard P. Signell, Peter A. Traykovski, John C. Warner
The freshwater transport and dynamics of the western Maine coastal current 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...
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 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...
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 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...
Authors
Jingping Xu, Fran Lightsom, Marlene A. Noble, Charles Denham
Report of the Community sediment transport modeling workshop 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 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...
Authors
Christopher R. Sherwood, Richard P. Signell, Courtney K. Harris, Bradford Butman
Predicting the physical effects of relocating Boston's sewage outfall 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...
Authors
R. P. Signell, H. L. Jenter, A.F. Blumberg
Bottom currents and sediment transport in Long Island Sound: A modeling study 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...
Authors
R. P. Signell, J. H. List, A.S. Farris
Modeling surface trapped river plumes: A sensitivity study 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...
Authors
Jason Hyatt, Richard P. Signell