Lentz Steven J.

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Steven J.

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  • Article
    Acceleration of a stratified current over a sloping bottom, driven by an alongshelf pressure gradient
    (American Meteorological Society, 2005-08) Chapman, David C. ; Lentz, Steven J.
    An idealized theoretical model is developed for the acceleration of a two-dimensional, stratified current over a uniformly sloping bottom, driven by an imposed alongshelf pressure gradient and taking into account the effects of buoyancy advection in the bottom boundary layer. Both downwelling and upwelling pressure gradients are considered. For a specified pressure gradient, the model response depends primarily on the Burger number S = Nα/f, where N is the initial buoyancy frequency, α is the bottom slope, and f is the Coriolis parameter. Without stratification (S = 0), buoyancy advection is absent, and the alongshelf flow accelerates until bottom stress balances the imposed pressure gradient. The e-folding time scale to reach this steady state is the friction time, h/r, where h is the water depth and r is a linear bottom friction coefficient. With stratification (S ≠ 0), buoyancy advection in the bottom boundary layer produces vertical shear, which prevents the bottom stress from becoming large enough to balance the imposed pressure gradient for many friction time scales. Thus, the alongshelf flow continues to accelerate, potentially producing large velocities. The acceleration increases rapidly with increasing S, such that even relatively weak stratification (S > 0.2) has a major impact. These results are supported by numerical model calculations.
  • Technical Report
    Coastal ocean processes inner-shelf study : coastal and moored physical oceanographic measurements
    (Woods Hole Oceanographic Institution, 1996-05) Alessi, Carol A. ; Lentz, Steven J. ; Austin, Jay A.
    To improve our understanding of the physical and biological processes influencing plantonic larval distributions over the inner shelf, an interdisciplinary field program funded by the National Science Foundation's Coastal Ocean Processes program (CoOP) was conducted near Duck, North Carolina in the southern porton of the Middle Atlantic Bight. The field program took place from August to December, 1994 and included both moored and shipboard measurements of physical, biological and sedimentological variables. This report summarizes the observations from one component of this field program, a moored array of physical oceanographic and meteorological instruments. This component of the field program consisted of a cross-shelf array of three surface/subsurface mooring pairs in 13 m, 20 m and 25 m of water supporting instruments to measure currents, temperature and conductivity, a suite of meteorological instruments on surface buoys at the 20 -m and 25 -m site, and an along-shelf array of temperature, conductivity and bottom pressure sensors mounted on jetted pipes along the 5-m isobath and on moorings along the 20-m isobath. The report includes descriptions of the cross-shelf and along-shelf arrays, the four types of instruments used (VAWRs, VMCMs, SeaCats, and SeaGauges), and the data return from the field program. Statistical and graphical summaries of the atmospheric (wind, air temperature, barometric pressure, relative humidity, short- and long-wave radiation), and oceanic (current, water temperature, conductivity and bottom pressure) measurements are presented.
  • Article
    The summer heat balance of the Oregon inner shelf over two decades: mean and interannual variability
    (American Geophysical Union, 2020-01-24) Lemagie, Emily ; Kirincich, Anthony R. ; Lentz, Steven J.
    Summer temperature and velocity measurements from 14 years in 15 m of water over the inner shelf off Oregon were used to investigate interannual temperature variability and the capacity of the across‐shelf heat flux to buffer net surface warming. There was no observable trend in summer mean temperatures, and the standard deviation of interannual variability (0.5°C) was less than the standard deviation in daily temperatures each summer (1.6°C, on average). Yet net surface heat flux provided a nearly constant source of heat each year, with a standard deviation less than 15 urn:x-wiley:jgrc:media:jgrc23812:jgrc23812-math-0001 of the interannual mean. The summer mean across‐shelf upwelling circulation advected warmer water offshore near the surface, cooling the inner shelf and buffering the surface warming. In most years (11 out of 14), this two‐dimensional heat budget roughly closed with a residual less than 20 urn:x-wiley:jgrc:media:jgrc23812:jgrc23812-math-0002 of the leading term. Even in years when the heat budget did not balance, the observed temperature change was negligible, indicating that an additional source of cooling was needed to close the budget. A comparison of the residual to the interannual variability in fields such as along‐shelf wind stress, stratification, and along‐shelf currents found no significant correlation, and further investigation into the intraseasonal dynamics is recommended to explain the results. An improved understanding of the processes that contribute to warming or cooling of the coastal ocean has the potential to improve predictions of the impact of year‐to‐year changes in local winds and circulation, such as from marine heat waves or climate change, on coastal temperatures.
  • Article
    Observations of tidal variability on the New England shelf
    (American Geophysical Union, 2004-06-04) Shearman, R. Kipp ; Lentz, Steven J.
    Observations from the Coastal Mixing and Optics experiment moored array, deployed from August 1996 through June 1997, are used to describe barotropic and baroclinic tidal variability over the New England shelf. The dominant M 2 tidal elevations decrease toward the northeast to a minimum over the Nantucket shoals (about 34 cm), and barotropic tidal current amplitudes increase strongly toward the northeast to a maximum over the shoals (about 35 cm s−1). Estimates of the depth-averaged M 2 momentum balance indicate that tidal dynamics are linear, and along-shelf pressure gradients are as large as cross-shelf pressure gradients. In addition, tidal current ellipses are weakly polarized, confirming that the dynamics are more complex than simple plane waves. The vertical structure of the M 2 currents decreases in amplitude and phase (phase lead near bottom) over the bottom 20 m. The M 2 momentum deficit near the bottom approximately matches direct covariance estimates of stress, confirming the effects of stress on current structure in the tidally driven bottom boundary layer. Baroclinic current variability at tidal frequencies is small (2 cm s−1 amplitude), with a predominantly mode 1 vertical structure. High-frequency (approaching the buoyancy frequency) internal solitons are observed following the pycnocline. The internal solitons switch from waves of depression to waves of elevation when the depth of maximum stratification is deeper than half the water column depth. Both low-mode baroclinic tidal and high-frequency internal wave energy decrease linearly with bottom depth across the shelf.
  • Preprint
    Observations of fresh, anticyclonic eddies in the Hudson Strait outflow
    ( 2010-07) Sutherland, David A. ; Straneo, Fiamma ; Lentz, Steven J. ; St-Laurent, Pierre
    The waters that flow out through Hudson Strait, a coastal system that connects Hudson Bay with the Labrador Sea, constitute the third largest freshwater contribution to the northern North Atlantic. Recent studies have documented the mean structure and transport of the outflow, as well as highlighting significant variability on synoptic scales (days–week). This study examines the outflow’s variability on these synoptic scales through the use of observations collected by a mooring array from 2005-2006. We focus on the mechanisms that cause the freshwater export to be concentrated in a series of discrete pulses during the fall/winter season. We find that the pulses occur once every 4.4 days on average and are associated with anticyclonic, surface-trapped eddies propagated through the strait by the mean outflow. Their occurrence is related to the passage of storms across Hudson Bay, although local instability processes also play a role in their formation. The eddies are responsible for approximately 40% of the mean volume transport and 50% of the mean freshwater transport out of the strait. We discuss the implications of this freshwater release mechanism on the delivery of nutrient-rich and highly stratified waters to the Labrador shelf, a productive region south of Hudson Strait.
  • Article
    The influence of wind forcing on the Chesapeake Bay buoyant coastal current
    (American Meteorological Society, 2006-07) Lentz, Steven J. ; Largier, John
    Observations of the buoyant coastal current that flows southward from Chesapeake Bay are used to describe how the thickness, width, and propagation speed vary in response to changes in the along-shelf wind stress. Three basic regimes were observed depending on the strength of the wind. For weak wind stresses (from −0.02 to 0.02 Pa), the buoyant coastal current was relatively thin, the front slope was not steep, and the width was variable (1–20 km). For moderate downwelling (southward) wind stresses (0.02–0.07 Pa), wind-driven cross-shelf advection steepened the front, causing the plume to narrow and thicken. For stronger downwelling wind stresses (greater than 0.07 Pa), vertical mixing dominated, bulk Richardson numbers were approximately 0.25, isopycnals were nearly vertical, and the plume front widened but the plume width did not change. Plume thickness and width were normalized by the theoretical plume scales in the absence of wind forcing. Normalized plume thickness increased linearly from 1 to 2 as downwelling wind stresses increased from 0 to 0.2 Pa. Normalized plume widths were approximately 1 for downwelling wind stresses from 0.02 to 0.2 Pa. The observed along-shelf propagation speed of the plume was roughly equal to the sum of the theoretical propagation speed and the wind-driven along-shelf flow.
  • Article
    Rapid generation of upwelling at a shelf break caused by buoyancy shutdown
    (American Meteorological Society, 2015-01) Benthuysen, Jessica A. ; Thomas, Leif N. ; Lentz, Steven J.
    Model analyses of an alongshelf flow over a continental shelf and slope reveal upwelling near the shelf break. A stratified, initially uniform, alongshelf flow undergoes a rapid adjustment with notable differences onshore and offshore of the shelf break. Over the shelf, a bottom boundary layer and an offshore bottom Ekman transport develop within an inertial period. Over the slope, the bottom offshore transport is reduced from the shelf’s bottom transport by two processes. First, advection of buoyancy downslope induces vertical mixing, destratifying, and thickening the bottom boundary layer. The downward-tilting isopycnals reduce the geostrophic speed near the bottom. The reduced bottom stress weakens the offshore Ekman transport, a process known as buoyancy shutdown of the Ekman transport. Second, the thickening bottom boundary layer and weakening near-bottom speeds are balanced by an upslope ageostrophic transport. The convergence in the bottom transport induces adiabatic upwelling offshore of the shelf break. For a time period after the initial adjustment, scalings are identified for the upwelling speed and the length scale over which it occurs. Numerical experiments are used to test the scalings for a range of initial speeds and stratifications. Upwelling occurs within an inertial period, reaching values of up to 10 m day−1 within 2 to 7 km offshore of the shelf break. Upwelling drives an interior secondary circulation that accelerates the alongshelf flow over the slope, forming a shelfbreak jet. The model results are compared with upwelling estimates from other models and observations near the Middle Atlantic Bight shelf break.
  • Article
    Interannual and seasonal along-shelf current variability and dynamics: seventeen years of observations from the southern New England inner shelf
    (American Meteorological Society, 2022-11-07) Lentz, Steven J.
    The characteristics and dynamics of depth-average along-shelf currents at monthly and longer time scales are examined using 17 years of observations from the Martha’s Vineyard Coastal Observatory on the southern New England inner shelf. Monthly averages of the depth-averaged along-shelf current are almost always westward, with the largest interannual variability in winter. There is a consistent annual cycle with westward currents of 5 cm s−1 in summer decreasing to 1–2 cm s−1 in winter. Both the annual cycle and interannual variability in the depth-average along-shelf current are predominantly driven by the along-shelf wind stress. In the absence of wind forcing, there is a westward flow of ∼5 cm s−1 throughout the year. At monthly time scales, the depth-average along-shelf momentum balance is primarily between the wind stress, surface gravity wave–enhanced bottom stress, and an opposing pressure gradient that sets up along the southern New England shelf in response to the wind. Surface gravity wave enhancement of bottom stress is substantial over the inner shelf and is essential to accurately estimating the bottom stress variation across the inner shelf.
  • Article
    River-discharge effects on United States Atlantic and Gulf coast sea-level changes
    (National Academy of Sciences, 2018-07-09) Piecuch, Christopher G. ; Bittermann, Klaus ; Kemp, Andrew C. ; Ponte, Rui Vasques de Melo ; Little, Christopher M. ; Engelhart, Simon E. ; Lentz, Steven J.
    Identifying physical processes responsible for historical coastal sea-level changes is important for anticipating future impacts. Recent studies sought to understand the drivers of interannual to multidecadal sea-level changes on the United States Atlantic and Gulf coasts. Ocean dynamics, terrestrial water storage, vertical land motion, and melting of land ice were highlighted as important mechanisms of sea-level change along this densely populated coast on these time scales. While known to exert an important control on coastal ocean circulation, variable river discharge has been absent from recent discussions of drivers of sea-level change. We update calculations from the 1970s, comparing annual river-discharge and coastal sea-level data along the Gulf of Maine, Mid-Atlantic Bight, South Atlantic Bight, and Gulf of Mexico during 1910–2017. We show that river-discharge and sea-level changes are significantly correlated (p<0.01), such that sea level rises between 0.01 and 0.08 cm for a 1 km3 annual river-discharge increase, depending on region. We formulate a theory that describes the relation between river-discharge and halosteric sea-level changes (i.e., changes in sea level related to salinity) as a function of river discharge, Earth’s rotation, and density stratification. This theory correctly predicts the order of observed increment sea-level change per unit river-discharge anomaly, suggesting a causal relation. Our results have implications for remote sensing, climate modeling, interpreting Common Era proxy sea-level reconstructions, and projecting coastal flood risk.
  • Article
    Momentum balances on the inner continental shelf at Martha's Vineyard Coastal Observatory
    (American Geophysical Union, 2010-12-09) Fewings, Melanie R. ; Lentz, Steven J.
    The subtidal, depth-average momentum balances in 12 m and 27 m water depth are investigated using observations from 2001 to 2007 of water velocity, temperature, and density; bottom pressure; surface gravity waves; and wind stress. In the fluctuating across-shelf momentum budget, the dominant terms are surface wind stress, pressure gradient, and Coriolis acceleration. The balance is a combination of (1) the geostrophic balance expected at midshelf sites and (2) the coastal setup and setdown balance driven by the across-shelf wind stress expected where surface and bottom boundary layers overlap. At the 12 m site, the estimated wave radiation stress gradient due to surface gravity wave shoaling is also large but is uncorrelated with the observed pressure gradient. A simple model suggests the wave radiation stress gradient is balanced by an across-shelf pressure gradient with a spatial scale too small to resolve with this mooring array. In the fluctuating along-shelf momentum balance, the dominant terms are surface wind stress, pressure gradient, and bottom stress at the shallower site, but the other estimated terms are not negligible. Our results support the Grant and Madsen (1986) formulation for wave-induced bottom stress. The fluctuating along-shelf pressure gradient is mainly a local sea level response to wind forcing, not a remotely generated pressure gradient. A strong correlation between along-shelf velocity and along-shelf wind stress at the shallower site is captured by a simple steady model of imbalance between wind stress and pressure gradient balanced by linear bottom drag.
  • Article
    The importance of lateral variability on exchange across the inner shelf south of Martha's Vineyard, MA
    (John Wiley & Sons, 2017-03-24) Kirincich, Anthony R. ; Lentz, Steven J.
    This study examines the spatial variability of transport within the inner-shelf south of Martha's Vineyard Massachusetts, its time and space dependence, and its importance to the total volume exchanged between the nearshore and the coastal ocean. The exchange of water across the inner shelf is often considered to be driven primarily by wind forcing, yet the effects of small-scale O(1–10 km) variability on the total exchange have not been well quantified. Using a combination of high-resolution HF radar-based surface currents and a dense array of moorings to document the lateral variability of across-shelf exchange, the cumulative wind-driven across-shelf transport over the summer stratified period was less than the volume of the inner-shelf onshore of the 25 m isobath. Along-shelf variations in the wind-driven exchange were as large as the spatial mean of the wind-driven exchange. A spatially varying time-averaged circulation caused by tidal rectification resulted in across-shelf exchange larger in magnitude than, and independent of, the integrated wind-forced exchange. Coherent submesoscale eddies also occurred frequently within the domain due to flow-topography effects onshore and horizontal density gradients offshore, generally with lifespans shorter than 10 h, diameters smaller than 6 km, and vertical depths shallower than 10 m. The across-shelf volume transport due to eddies, estimated by seeding particles within the surface current fields, was more than half the wind-driven depth-dependent exchange. Thus, accounting for the potential coherent along-shelf variability present over the inner shelf can significantly increase estimates of the across-shelf transfer of water masses and particles.
  • Technical Report
    The 1995 Georges Bank Stratification Study and moored array measurements
    (Woods Hole Oceanographic Institution, 2001-08) Alessi, Carol A. ; Beardsley, Robert C. ; Caruso, Michael J. ; Churchill, James H. ; Irish, James D. ; Lentz, Steven J. ; Limeburner, Richard ; Werner, R. ; Weller, Robert A. ; Williams, Albert J. ; Williams, William J. ; Manning, James P. ; Smith, P.
    The 1995 Geoges Bank Stratification Study (GBSS) was the first intensive process study conducted as part of the U.S. GLOBEC Northwest Atlantic/Georges Bank field program. The GBSS was designed to investigate the physical processes which control the seasonal development of stratification along the southern flank of Georges Bank during spring and summer. Past work suggested that during this period, larval cod and haddock tended to aggregate to the thermocline on the southern flank where higher concentrations of their copepod prey were found. A moored array was deployed as part of GBSS to observe the onset and evolution of sesonal stratification over the southern flank with sufficient vertical and horizontal resolution that key physical processes could be identified and quantified. Moored current, temperature, and conductivity (salinity) measurements were made at three sites along the southern flank, one on the crest, and one on the northeast peak of the bank. Moored surface meteorological measurements were also made at one southern flank site to determine the surface wind stress and heat and moisture fluxes. The oceanographic and meteorological data collected with the GBSS array during January-August 1995 are presented in this report. Meteorological data collected on National Data Buoy Center environmental buoys 44011 (Georges Bank), 44008 (Nantucket Shoals), and 44005 (Gulf of Maine) are included in this report for completeness and comparison with the GBSS southern flank meteorological measurements.
  • Technical Report
    Shelf MIxed Layer Experiment (SMILE) program description and coastal and moored array data report
    (Woods Hole Oceanographic Institution, 1991-12) Alessi, Carol A. ; Lentz, Steven J. ; Beardsley, Robert C.
    The Shelf MIxed Layer Experiment (SMILE) was designed to study the response of the oceanic surface boundary layer over the continental shelf to atmospheric forcing. The SMILE field program was conducted over the northern California shelf between Pt. Arena and Pt. Reyes from mid-November 1988 to mid-May 1989. The field program consisted of five main components: (a) a long-term moored array to obtain current, temperature, and conductivity time series observations in the upper ocean over the shelf; (b) a short-term moored instrument deployment to measure the vertical current shear and stratification in the top 6 m of the water column; (c) shipboard CTD and acoustic Doppler current profiler (ADCP) surveys over the shelf and adjacent slope to map regional water property and current distributions; (d) a long-term moored and coastal meteorological array including one sounding station to obtain time series observations of the atmospheric surface forcing and monitor the structure of the marine boundary layer; and (e) overflights with an instrumented aircraft to measure the spatial structure of the surface wind, wind stress, and heat flux fields under different atmospheric conditions. This report has two objectives: (a) to describe the SMILE field program, including overviews of the five components, and (b) to present a statistical and graphical summary of the atmospheric (wind, air temperature, pressure, relative humidity, short- and longwave radiation) and oceanic (current, water temperature, and conductivity) long-term array measurements made as part of SMILE. A more detailed description of the instrumentation used in SMILE and an assessment of instrument performance and accuracy are presented separately by Dean et al. (1991).
  • Article
    Investigating the eddy diffusivity concept in the coastal ocean
    (American Meteorological Society, 2016-06-29) Rypina, Irina I. ; Kirincich, Anthony R. ; Lentz, Steven J. ; Sundermeyer, Miles A.
    This paper aims to test the validity, utility, and limitations of the lateral eddy diffusivity concept in a coastal environment through analyzing data from coupled drifter and dye releases within the footprint of a high-resolution (800 m) high-frequency radar south of Martha’s Vineyard, Massachusetts. Specifically, this study investigates how well a combination of radar-based velocities and drifter-derived diffusivities can reproduce observed dye spreading over an 8-h time interval. A drifter-based estimate of an anisotropic diffusivity tensor is used to parameterize small-scale motions that are unresolved and underresolved by the radar system. This leads to a significant improvement in the ability of the radar to reproduce the observed dye spreading.
  • Article
    Surface gravity wave transformation across a platform coral reef in the Red Sea
    (John Wiley & Sons, 2016-01-22) Lentz, Steven J. ; Churchill, James H. ; Davis, Kristen A. ; Farrar, J. Thomas
    The transformation of surface gravity waves across a platform reef in the Red Sea is examined using 18 months of observations and a wave transformation model developed for beaches. The platform reef is 200 m across, 700 m long, and the water depth varies from 0.3 to 1.2 m. Assuming changes in wave energy flux are due to wave breaking and bottom drag dissipation, the wave transformation model with optimal parameters characterizing the wave breaking (γm = 0.25) and bottom drag (hydrodynamic roughness zo = 0.08 m) accounts for 75%–90% of the observed wave-height variance at four sites. The observations and model indicate that wave breaking dominates the dissipation in a 20–30 m wide surf zone while bottom drag dominates the dissipation over the rest of the reef. Friction factors (drag coefficients) estimated from the observed wave energy balance range from fw = 0.5 to fw = 5 and increase as wave-orbital displacements decrease. The observed dependence on wave-orbital displacement is roughly consistent with extrapolation of an empirical relationship based on numerous laboratory studies of oscillatory flow. As a consequence of the dependence on wave-orbital displacement, wave friction factors vary temporally due to changes in water depth and incident wave heights, and spatially across the reef as the waves decay.
  • Article
    Wind-driven circulation in a shelf valley. Part II : Dynamics of the along-valley velocity and transport
    (American Meteorological Society, 2018-04-16) Zhang, Weifeng G. ; Lentz, Steven J.
    The dynamics controlling the along-valley (cross shelf) flow in idealized shallow shelf valleys with small to moderate Burger number are investigated, and analytical scales of the along-valley flows are derived. This paper follows Part I, which shows that along-shelf winds in the opposite direction to coastal-trapped wave propagation (upwelling regime) force a strong up-valley flow caused by the formation of a lee wave. In contrast, along-shelf winds in the other direction (downwelling regime) do not generate a lee wave and consequently force a relatively weak net down-valley flow. The valley flows in both regimes are cyclostrophic with 0(1) Rossby number. A major difference between the two regimes is the along-shelf length scales of the along-valley flows L. In the upwelling regime Ls, depends on the valley width W, and the wavelength lambda(1w) of the coastal-trapped lee wave arrested by the along-shelf flow U-s. In the downwelling regime L depends on the inertial length scale U-s|'f and W-c. The along-valley velocity scale in the upwelling regime, given by V-u approximate to root pi H-c/H-s integral W-c lambda(1w)/2 pi L-x (1+L-x(2)/L-c(2))(-1) e(-(pi Wc)/(lambda 1w),) is based on potential vorticity (PV) conservation and lee-wave dynamics (Hs and H, are the shelf and valley depth scales, respectively, and fis the Coriolis parameter). The velocity scale in the downwelling regime, given by |v(d)| approximate to (H-s/H-s)[1 + (L-x(2)/L-x(2))](-1) fL, is based on PV conservation. The velocity scales are validated by the numerical sensitivity simulations and can be useful for observational studies of along -valley transports. The work provides a framework for investigating cross -shelf transport induced by irregular shelf bathymetry and calls for future studies of this type under realistic environmental conditions and over a broader parameter space.
  • Article
    Coral reef drag coefficients—surface gravity wave enhancement
    (American Meteorological Society, 2018-07-13) Lentz, Steven J. ; Churchill, James H. ; Davis, Kristen A.
    A primary challenge in modeling flow over shallow coral reefs is accurately characterizing the bottom drag. Previous studies over continental shelves and sandy beaches suggest surface gravity waves should enhance the drag on the circulation over coral reefs. The influence of surface gravity waves on drag over four platform reefs in the Red Sea is examined using observations from 6-month deployments of current and pressure sensors burst sampling at 1Hz for 4–5min. Depth-average current fluctuations U0 within each burst are dominated by wave orbital velocities uw that account for 80%–90%of the burst variance and have a magnitude of order 10 cm s21, similar to the lower-frequency depth-average current Uavg. Previous studies have shown that the cross-reef bottom stress balances the pressure gradient over these reefs. A bottom stress estimate that neglects the waves (rCdaUavgjUavgj, where r is water density and Cda is a drag coefficient) balances the observed pressure gradient when uw is smaller than Uavg but underestimates the pressure gradient when uw is larger than Uavg (by a factor of 3–5 when uw 5 2Uavg), indicating the neglected waves enhance the bottom stress. In contrast, a bottom stress estimate that includes the waves [rCda(Uavg 1 U0)jUavg 1 U0j)] balances the observed pressure gradient independent of the relative size of uw and Uavg, indicating that this estimate accounts for the wave enhancement of the bottom stress. A parameterization proposed by Wright and Thompson provides a reasonable estimate of the total bottom stress (including the waves) given the burst-averaged current and the wave orbital velocity.
  • Article
    Long-term sea surface temperature variability along the U.S. East Coast
    (American Meteorological Society, 2010-05) Shearman, R. Kipp ; Lentz, Steven J.
    Sea surface temperature variations along the entire U.S. East Coast from 1875 to 2007 are characterized using a collection of historical observations from lighthouses and lightships combined with recent buoy and shore-based measurements. Long-term coastal temperature trends are warming in the Gulf of Maine [1.0° ± 0.3°C (100 yr)−1] and Middle Atlantic Bight [0.7° ± 0.3°C (100 yr)−1], whereas trends are weakly cooling or not significant in the South Atlantic Bight [−0.1° ± 0.3°C (100 yr)−1] and off Florida [−0.3° ± 0.2°C (100 yr)−1]. Over the last century, temperatures along the northeastern U.S. coast have warmed at a rate 1.8–2.5 times the regional atmospheric temperature trend but are comparable to warming rates for the Arctic and Labrador, the source of coastal ocean waters north of Cape Hatteras (36°N). South of Cape Hatteras, coastal ocean temperature trends match the regional atmospheric temperature trend. The observations and a simple model show that along-shelf transport, associated with the mean coastal current system running from Labrador to Cape Hatteras, is the mechanism controlling long-term temperature changes for this region and not the local air–sea exchange of heat.
  • Technical Report
    Fluid mechanical measurements within the boundary layer over the northern California Continental Shelf during STRESS
    (Woods Hole Oceanographic Institution, 1993-09) Fredericks, Janet J. ; Trowbridge, John H. ; Williams, Albert J. ; Lentz, Steven J. ; Butman, Bradford ; Gross, Thomas F.
    In studying the processes controlling particle distrbution of fine sediments over the continental shelf, the height, structure and dynamics of the bottom boundary layer must be better understood. The Sediment Transport Events on Shelves and Slopes (STRESS) program provides a comprehensive set of data over the bottom half of the water column at the 90m and the 130m isobaths along the northern California continental shelf during the winters of 1988-89 and 1990-91. This report presents the STRESS salinity, temperature, velocity, wave characteristics and attenuation data. The report describes the processing, provides plots and tables of the data and corresponding statistics for evaluation of the data, and documents the data fies. The combined set of moored and tripod mounted instrument measurements provides integrated, hourly-averaged profiles of the lower half of the water column at the four sites which can be used for analysis and modeling purposes.
  • Dataset
    Event logs from the U.S. GLOBEC Georges Bank project, from 10 vessels and 104 cruises in the Gulf of Maine and Georges Bank area from 1994-1999 (GB project)
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2019-02-18) Ashjian, Carin J. ; Bollens, Steve M. ; Bucklin, Ann ; Campbell, Robert ; Davis, Cabell S. ; Durbin, Edward ; Gallager, Scott ; Garrahan, Peter ; Gibson, James ; Gifford, Dian J. ; Green, John ; Greene, Charles H ; Hebert, Dave ; Horgan, Erich ; Houghton, Robert W ; Incze, Lewis ; Irish, Jim ; Ledwell, James R. ; Lentz, Steven J. ; Limeburner, Richard ; Lough, Greg ; Madin, Laurence P. ; Miller, Charles B. ; Mountain, David ; Oakey, Neil ; Schlitz, Ronald ; Sibunka, John ; Smith, Peter C. ; Taylor, Maureen ; Weller, Robert A. ; Wiebe, Peter H. ; Williams, Albert J. ; Wishner, Karen ; Lee, Craig
    Event logs from the U.S. GLOBEC Georges Bank project, from 10 vessels and 104 cruises in the Gulf of Maine and Georges Bank area from 1994-1999. Event logs provide an overall summary of the sampling activities during a cruise. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/2321