Geology Reports⌕ Search

Geology topics

Research about Massachusetts Bay

Source-linked reports with geographic coverage including Massachusetts Bay.

At least 19 recordsLinked to original sources
USGS2008

Shoaling of nonlinear internal waves in Massachusetts Bay

The shoaling of the nonlinear internal tide in Massachusetts Bay is studied with a fully nonlinear and nonhydrostatic model. The results are compared with current and temperature observations obtained during the August 1998 Massachusetts Bay Internal Wave Experiment and observations from a shorter experiment which took place in September 2001. The model shows how the approaching nonlinear undular bore interacts strongly with a shoaling bottom, offshore of where KdV theory predicts polarity switching should occur. It is shown that the shoaling process is dominated by nonlinearity, and the model results are interpreted with the aid of a two-layer nonlinear but hydrostatic model. After interacting with the shoaling bottom, the undular bore emerges on the shallow shelf inshore of the 30-m isobath as a nonlinear internal tide with a range of possible shapes, all of which are found in the available observational record. Copyright 2008 by the American Geophysical Union.

Masschusetts↗
USGS2008

Northeast storms ranked by wind stress and wave-generated bottom stress observed in Massachusetts Bay, 1990-2006

Along the coast of the northeastern United States, strong winds blowing from the northeast are often associated with storms called northeasters, coastal storms that strongly influence weather. In addition to effects caused by wind stress, the sea floor is affected by bottom stress associated with these storms. Bottom stress caused by orbital velocities associated with surface waves integrated over the duration of a storm is a metric of storm strength at the sea floor. Near-bottom wave-orbital velocities calculated by using measurements of significant wave height and dominant wave period and the parametric spectral method described in Wiberg and Sherwood [Wiberg, P.L., Sherwood, C.R. Calculating wave-generated bottom orbital velocities from surface wave parameters. Computers in Geosciences, in press] compared well with observations in Massachusetts Bay. Integrated bottom-wave stress (called IWAVES), calculated at 30 m water depth, and a companion storm-strength metric, integrated surface wind stress at 10 m (called IWINDS), are used to provide an overview of the strength, frequency, and timing of large storms in Massachusetts Bay over a 17-year period from January 1990 through December 2006. These new metrics reflect both storm duration and intensity. Northeast storms were the major cause of large waves in Massachusetts Bay because of the long fetch to the east: of the strongest 10% of storms (n=38) ranked by IWAVES, 22 had vector-averaged wind stress from the northeast quadrant. The Blizzard of December 1992, the Perfect Storm of October 1991, and a December 2003 storm were the strongest three storms ranked by IWAVES and IWINDS, and all were northeasters. IWAVES integrated over the winter season (defined as October-May) ranged by about a factor of 11; the winters with the highest integrated IWAVES were 1992-1993 and 2004-2005 and the winter with the lowest integrated IWAVES was 2001-2002. May 2005 was the only month in the 17-year record that two of the nine strongest northeast storms ranked by IWINDS occurred in the same month or year; these were also the only storms of the nine strongest northeast storms to occur in the spring.

Massachusetts Bay↗
USGS2008

Time-series photographs of the sea floor in western Massachusetts Bay, version 2, 1989 - 1996

Time-series photographs of the sea floor were obtained from an instrumented tripod deployed in western Massachusetts Bay at LT-A (42° 22.6' N, 70° 47.0' W; nominal water depth of 32 m; fig. 1) from December 1989 through September 2005. The photographs provide time-series observations of physical changes of the sea floor, near-bottom water turbidity, and life on the sea floor. Several reports present these photographs in digital form (table 1). This report, U.S. Geological Survey Data Series 265, Version 2.0, contains the photographs obtained from December 1989 to October 1996, adding to (and replacing) Version 1 of Data Series 265 (Butman and others, 2007a) that contained photographs from 1989 through 1993. Data Series 266 (Butman and others, 2008b) contains photographs obtained from October 1996 through September 2005. The photographs are published in separate reports because the data files are too large for distribution on a single DVD. These reports present the photographs, originally collected on 35-mm film, in digital form to enable easy viewing and to provide a medium-resolution digital archive. The photographs, obtained every 4 or every 6 hours, are presented as individual photographs (in .png format) and as a movie (in .avi format). The time-series photographs taken at LT-A were collected as part of a U.S. Geological Survey (USGS) study to understand the transport and fate of sediments and associated contaminants in Massachusetts Bay and Cape Cod Bay (Bothner and Butman, 2007). This long-term study was carried out by the USGS in partnership with the Massachusetts Water Resources Authority (MWRA) (https://www.mwra.state.ma.us/) and with logistical support from the U.S. Coast Guard (USCG). Long-term oceanographic observations help to identify the processes causing bottom sediment resuspension and transport and provide data for developing and testing numerical models. The observations document seasonal and interannual changes in currents, hydrography, suspended-matter concentration, and the importance of infrequent catastrophic events, such as major storms, in sediment resuspension and transport. LT-A is approximately 1 km south of the ocean outfall that began discharging treated sewage effluent from the Boston metropolitan area into Massachusetts Bay in September 2000. See Butman and others (2004d) for a description of the oceanographic measurements at LT-A, and Butman and others (2007c) and Warner and others (2008) for discussion of sediment transport in Massachusetts Bay.

Massachusetts↗
USGS2008

Time-series photographs of the sea floor in western Massachusetts Bay, 1996 - 2005

Time-series photographs of the sea floor were obtained from an instrumented tripod deployed in western Massachusetts Bay at LT-A (42° 22.6' N, 70° 47.0' W; 32 m water depth; fig. 1 ) from December 1989 through September 2005. The photographs provide time-series observations of physical changes of the sea floor, near-bottom water turbidity, and life on the sea floor. Two reports present these photographs in digital form ( table 1 ) and chronological order. U.S. Geological Survey Data Series 265 (Butman and others, 2008a) contains the photographs obtained from December 1989 to October 1996. This report, U.S. Geological Survey Data Series 266 (Butman and others, 2008b), contains photographs obtained from October 1996 through September 2005. The photographs are published in separate reports because the data files are too large for distribution on a single DVD. This report also contains photographs that were published previously in an uncompressed format (Butman and others 2004a, b, and c; table 1 ); they have been compressed and included in this publication so that all of the photographs are available in the same format. The photographs, obtained every 4 or every 6 hours, are presented as individual photographs (in .png format, each accessible through a page of thumbnails) and as a movie (in .avi format). The time-series photographs taken at LT-A were collected as part of a U.S. Geological Survey (USGS) study to understand the transport and fate of sediments and associated contaminants in Massachusetts Bay and Cape Cod Bay (Bothner and Butman, 2007). This long-term study was carried out by the USGS in partnership with the Massachusetts Water Resources Authority (MWRA) ( https://www.mwra.state.ma.us/ ) and with logistical support from the U.S. Coast Guard (USCG). Long-term oceanographic observations help to identify the processes causing bottom sediment resuspension and transport and provide data for developing and testing numerical models. The observations document seasonal and interannual changes in currents, hydrography, suspended-matter concentration, and the importance of infrequent catastrophic events, such as major storms, in sediment resuspension and transport. LT-A is approximately 1 km south of the ocean outfall that began discharging treated sewage effluent from the Boston metropolitan area into Massachusetts Bay in September 2000. See Butman and others (2004d) and Butman and others (2007a) for a description of the oceanographic measurements at LT-A. See Butman and others (2007c) and Warner and others (2008) for discussion of sediment transport in Massachusetts Bay.

Massachusetts Bay↗
USGS2007

Long-term performance of Aanderaa optodes and sea-bird SBE-43 dissolved-oxygen sensors bottom mounted at 32 m in Massachusetts Bay

A field evaluation of two new dissolved-oxygen sensing technologies, the Aanderaa Instruments AS optode model 3830 and the Sea-Bird Electronics, Inc., model SBE43, was carried out at about 32-m water depth in western Massachusetts Bay. The optode is an optical sensor that measures fluorescence quenching by oxygen molecules, while the SBE43 is a Clark polarographic membrane sensor. Optodes were continuously deployed on bottom tripod frames by exchanging sensors every 4 months over a 19-month period. A Sea-Bird SBE43 was added during one 4-month deployment. These moored observations compared well with oxygen measurements from profiles collected during monthly shipboard surveys conducted by the Massachusetts Water Resources Authority. The mean correlation coefficient between the moored measurements and shipboard survey data was >0.9, the mean difference was 0.06 mL L −1 , and the standard deviation of the difference was 0.15 mL L −1 . The correlation coefficient between the optode and the SBE43 was >0.9 and the mean difference was 0.07 mL L −1 . Optode measurements degraded when fouling was severe enough to block oxygen molecules from entering the sensing foil over a significant portion of the sensing window. Drift observed in two optodes beginning at about 225 and 390 days of deployment is attributed to degradation of the sensing foil. Flushing is necessary to equilibrate the Sea-Bird sensor. Power consumption by the SBE43 and required pump was 19.2 mWh per sample, and the optode consumed 0.9 mWh per sample, both within expected values based on manufacturers’ specifications.

Massachusetts↗
USGS2007

Generation and propagation of nonlinear internal waves in Massachusetts Bay

During the summer, nonlinear internal waves (NLIWs) are commonly observed propagating in Massachusetts Bay. The topography of the area is unique in the sense that the generation area (over Stellwagen Bank) is only 25 km away from the shoaling area, and thus it represents an excellent natural laboratory to study the life cycle of NLIWs. To assist in the interpretation of the data collected during the 1998 Massachusetts Bay Internal Wave Experiment (MBIWE98), a fully nonlinear and nonhydrostatic model covering the generation/shoaling region was developed, to investigate the response of the system to the range of background and driving conditions observed. Simplified models were also used to elucidate the role of nonlinearity and dispersion in shaping the NLIW field. This paper concentrates on the generation process and the subsequent evolution in the basin. The model was found to reproduce well the range of propagation characteristics observed (arrival time, propagation speed, amplitude), and provided a coherent framework to interpret the observations. Comparison with a fully nonlinear hydrostatic model shows that during the generation and initial evolution of the waves as they move away from Stellwagen Bank, dispersive effects play a negligible role. Thus the problem can be well understood considering the geometry of the characteristics along which the Riemann invariants of the hydrostatic problem propagate. Dispersion plays a role only during the evolution of the undular bore in the middle of Stellwagen Basin. The consequences for modeling NLIWs within hydrostatic models are briefly discussed at the end.

Massachusetts↗
USGS2006

On the interpretation of energy and energy fluxes of nonlinear internal waves: An example from Massachusetts Bay

A self-consistent formalism to estimate baroclinic energy densities and fluxes resulting from the propagation of internal waves of arbitrary amplitude is derived using the concept of available potential energy. The method can be applied to numerical, laboratory or field data. The total energy flux is shown to be the sum of the linear energy flux ??? u??? p??? dz (primes denote baroclinic quantities), plus contributions from the non-hydrostatic pressure anomaly and the self-advection of kinetic and available potential energy. Using highly resolved observations in Massachusetts Bay, it is shown that due to the presence of nonlinear internal waves periodically propagating in the area, ??? u??? p??? dz accounts for only half of the total flux. The same data show that equipartition of available potential and kinetic energy can be violated, especially when the nonlinear waves begin to interact with the bottom. ?? 2006 Cambridge University Press.

Massachusetts Bay↗
USGS2006

Large internal waves in Massachusetts Bay transport sediments offshore

A field experiment was carried out in Massachusetts Bay in August 1998 to assess the role of large-amplitude internal waves (LIWs) in resuspending bottom sediments. The field experiment consisted of a four-element moored array extending from just west of Stellwagen Bank (90-m water depth) across Stellwagen Basin (85- and 50-m water depth) to the coast (24-m water depth). The LIWs were observed in packets of 5–10 waves, had periods of 5–10 min and wavelengths of 200–400 m, and caused downward excursions of the thermocline of as much as 30 m. At the 85-m site, the current measured 1 m above bottom (mab) typically increased from near 0 to 0.2 m/s offshore in a few minutes upon arrival of the LIWs. At the 50-m site, the near-bottom offshore flow measured 6 mab increased from about 0.1 to 0.4–0.6 m/s upon arrival of the LIWs and remained offshore in the bottom layer for 1–2 h. The near-bottom currents associated with the LIWs, in concert with the tidal currents, were directed offshore and sufficient to resuspend the bottom sediments at both the 50- and 85-m sites. When LIWs are present, they may resuspend sediments for as long as 5 hours each tidal cycle as they travel westward across Stellwagen Basin. At 85-m water depth, resuspension associated with LIWs is estimated to occur for about 0.4 days each summer, about the same amount of time as caused by surface waves.

Massachusetts↗
USGS2006

The Massachusetts Bay internal wave experiment, August 1998: Data report

This data report presents oceanographic observations made in Massachusetts Bay (fig. 1) in August 1998 as part of the Massachusetts Bay Internal Wave Experiment (MBIWE98). MBIWE98 was carried out to characterize large-amplitude internal waves in Massachusetts Bay and to investigate the possible resuspension and transport of bottom sediments caused by these waves. This data report presents a description of the field program and instrumentation, an overview of the data through summary plots and statistics, and the time-series data in NetCDF format. The objective of this report is to make the data available in digital form and to provide summary plots and statistics to facilitate browsing of the data set. The existence of large-amplitude internal waves in Massachusetts Bay was first described by Halpern (1971). In summer when the water is stratified, packets of waves propagate westward into the bay on the flood (westward flowing) tide at about 0.5 m/s. The internal waves are observed in packets of 5-10 waves, have periods of 5-10 minutes and wavelengths of 200-400 m, and cause downward excursions of the thermocline of as much as 30 m. The waves are generated by interaction of the barotropic tide with Stellwagen Bank (Haury and others (1979). Several papers present analyses and interpretations of the data collected during the MBIWE98. Grosenbaugh and others (2002) report on the results of the horizontal array, Scotti and others (2005) describe a strategy for processing observations made by Acoustic Doppler Current Profilers (ADCPs) in the presence of short-wavelength internal waves, Butman and others (in press) describe the effect of these waves on sediment transport, and Scotti and others (in press) describe the energetics of the internal waves.

Massachusetts↗
USGS2004

Bioturbation depths, rates and processes in Massachusetts Bay sediments inferred from modeling of 210Pb and 239 + 240Pu profiles

Profiles of 210 Pb and 239 + <240 Pu from sediment cores collected throughout Massachusetts Bay (water depths of 36-192 m) are interpreted with the aid of a numerical sediment-mixing model to infer bioturbation depths, rates and processes. The nuclide data suggest extensive bioturbation to depths of 25-35 cm. Roughly half the cores have 210 Pb and 239 + 240 Pu profiles that decrease monotonically from the surface and are consistent with biodiffusive mixing. Bioturbation rates are reasonably well constrained by these profiles and vary from ~0.7 to ~40 cm 2 yr -1 . As a result of this extensive reworking, however, sediment ages cannot be accurately determined from these radionuclides and only upper limits on sedimentation rates (of ~0.3 cm yr -1 ) can be inferred. The other half of the radionuclide profiles are characterized by subsurface maxima in each nuclide, which cannot be reproduced by biodiffusive mixing models. A numerical model is used to demonstrate that mixing caused by organisms that feed at the sediment surface and defecate below the surface can cause the subsurface maxima, as suggested by previous work. The deep penetration depths of excess 210 Pb and 239 + 240 Pu suggest either that the organisms release material over a range of >15 cm depth or that biodiffusive mixing mediated by other organisms is occurring at depth. Additional constraints from surficial sediment 234 Th data suggest that in this half of the cores, the vast majority of the present-day flux of recent, nuclide-bearing material to these core sites is transported over a timescale of a month or more to a depth of a few centimeters below the sediment surface. As a consequence of the complex mixing processes, surface sediments include material spanning a range of ages and will not accurately record recent changes in contaminant deposition.

Massachusetts↗
USGS2004

Time-series photographs of the sea floor in western Massachusetts Bay: June 1997 to June 1998

This report presents time-series photographs of the sea floor obtained from an instrumented tripod deployed at Site A in western Massachusetts Bay (42° 22.6' N., 70? 47.0' W., 30 m water depth, from June 1997 through June 1998. Site A is approximately 1 km south of an ocean outfall that began discharging treated sewage effluent from the Boston metropolitan area into Massachusetts Bay in September 2000. Time-series photographs and oceanographic observations were initiated at Site A in December 1989 and are anticipated to continue to September 2005. This is the first in a series of reports planned to summarize and distribute these images in digital form. The objective of these reports is to enable easy and rapid viewing of the photographs and to provide a medium-resolution digital archive. The images, obtained every 4 hours, are presented as a movie (in .avi format, which may be viewed using an image viewer such as QuickTime or Windows Media Player) and as individual images (.tif format). The images provide time-series observations of changes of the sea floor and near-bottom water properties.

Massachusetts↗
USGS2002

Design and performance of a horizontal mooring for upper-ocean research

This paper describes the design and performance of a two-dimensional moored array for sampling horizontal variability in the upper ocean. The mooring was deployed in Massachusetts Bay in a water depth of 84 m for the purpose of measuring the horizontal structure of internal waves. The mooring was instrumented with three acoustic current meters (ACMs) spaced along a 170-m horizontal cable that was stretched between two subsurface buoys 20 m below the sea surface. Five 25-m-long vertical instrument strings were suspended from the horizontal cable. A bottom-mounted acoustic Doppler current profiler (ADCP) was deployed nearby to measure the current velocity throughout the water column. Pressure sensors mounted on the subsurface buoys and the vertical instrument strings were used to measure the vertical displacements of the array in response to the currents. Measurements from the ACMs and the ADCP were used to construct time-dependent, two-dimensional current fields. The current fields were used as input to a numerical model that calculated the deformation of the array with respect to the nominal zero-current configuration. Comparison of the calculated vertical offsets of the downstream subsurface buoy and downstream vertical instrument string with the pressure measurements were used to verify the numerical code. These results were then used to estimate total deformation of the array due to the passage of the internal waves. Based on the analysis of the three internal wave events with the highest measured vertical offsets, it is concluded that the geometry of the main structure (horizontal cable and anchor legs) was kept to within ±2.0 m, and the geometry of the vertical instrument strings was kept to within ±4.0 m except for one instance when the current velocity reached 0.88 m s −1 .

Massachusetts↗
USGS2000

Portable coastal observatories

Ocean observational science is in the midst of a paradigm shift from an expeditionary science centered on short research cruises and deployments of internally recording instruments to a sustained observational science where the ocean is monitored on a regular basis, much the way the atmosphere is monitored. While satellite remote sensing is one key way of meeting the challenge of real-time monitoring of large ocean regions, new technologies are required for in situ observations to measure conditions below the ocean surface and to measure ocean characteristics not observable from space. One method of making sustained observations in the coastal ocean is to install a fiber optic cable from shore to the area of interest. This approach has the advantage of providing power to offshore instruments and essentially unlimited bandwidth for data. The LEO-15 observatory offshore of New Jersey (yon Alt et al., 1997) and the planned Katama observatory offshore of Martha's Vineyard (Edson et al., 2000) use this approach. These sites, along with other cabled sites, will play an important role in coastal ocean science in the next decade. Cabled observatories, however, have two drawbacks that limit the number of sites that are likely to be installed. First, the cable and the cable installation are expensive and the shore station needed at the cable terminus is often in an environmentally sensitive area where competing interests must be resolved. Second, cabled sites are inherently limited geographically to sites within reach of the cable, so it is difficult to cover large areas of the coastal ocean.

Massachusetts Bay↗
USGS1996

Open-ocean boundary conditions from interior data: Local and remote forcing of Massachusetts Bay

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 boundary. Results compare reasonably well with observed currents near the coast. In some offshore regions, however, modeled flows are an order of magnitude less energetic than the data. Strong flows are observed even during periods of weak local wind forcing. Poor model-data comparisons are attributable, at least in part, to open-ocean boundary conditions that neglect the effects of remote forcing. Velocity measurements from within Massachusetts Bay are used to estimate the remotely forced component of the flow. The data are combined with shallow water dynamics in an inverse-model formulation that follows the theory of Bennett and McIntosh [1982], who considered tides. We extend their analysis to consider the subtidal response to transient forcing. The inverse model adjusts the a priori open-ocean boundary condition, thereby minimizing a combined measure of model-data misfit and boundary condition adjustment. A “consistency criterion” determines the optimal trade-off between the two. The criterion is based on a measure of plausibility for the inverse solution. The “consistent” inverse solution reproduces 56% of the average squared variation in the data. The local-wind-driven flow alone accounts for half of the model skill. The other half is attributable to remotely forced flows from the Gulf of Maine. The unexplained 44% comes from measurement errors and model errors that are not accounted for in the analysis.

Massachusetts↗
USGS1995

Seafloor environments within the Boston Harbor- Massachusetts Bay sedimentary system: A regional synthesis

Modern seafloor sedimentary environments within the glaciated, topographically complex Boston Harbor and Massachusetts Bay area have been interpreted and mapped from an extensive collection of sidescan sonar records and supplemental marine geologic data. Three categories of environments are present that reflect the dominant long-term processes of erosion or nondeposition, deposition, and sediment reworking. (1) Environments of erosion or nondeposition comprise exposures of bedrock, glacial drift, coarse lag deposits, and possibly coastal plain rocks that contain sediments (where present) ranging from boulder fields to gravelly sands and occur in areas of relatively strong currents. (2) Environments of deposition contain fine-grained sediments ranging from muddy sands to muds that have accumulated in areas of predominantly weak bottom currents. (3) Environments of sediment reworking contain patches with textures ranging from sandy gravels to muds that have been produced by a combination of erosion and deposition in areas with variable bottom currents. The distribution of sedimentary environments across the Boston Harbor-Massachusetts Bay area is extremely patchy. Locally, this patchiness is due either to modifications of bottom-current strength (caused by the irregular topography and differences in water depth) or to small-scale changes in the supply of fine-grained sediments. Regional patchiness, however, reflects differences in geologic and oceanographic conditions among the estuarine, inner shelf, and basinal parts of the sedimentary system. The estuarine part of the system (Boston Harbor) is a depositional trap for fine-grained sediments because it is protected from large waves, has generally weak and variable tidal currents, and receives a large supply of fine grained detritus from natural and anthropogenic sources. The inner shelf, on the other hand, is largely an area of erosion or nondeposition due to sediment removal and redistribution during past sea-level changes, to sediment resuspension and winnowing by modern waves and currents, and to an inadequate supply of fine-grained sediments. The basinal part of the system (Stellwagen Basin) is mainly a tranquil depositional environment in which fine-grained sediments from several potential sources settle through the water column and accumulate under weak bottom currents. This study indicates areas within the Boston Harbor-Massachusetts Bay sedimentary system where fine-grained sediments and associated contaminants are likely to be either moved or deposited. It also provides a guide to the locations and variability of benthic habitats.

Massachusetts Bay↗