A large‐amplitude meander of the shelfbreak front during summer south of New England: Observations from the Shelfbreak PRIMER experiment

Gawarkiewicz, Glen; Brink, Kenneth H.; Bahr, Frank; Beardsley, Robert C.; Caruso, Michael J.; Lynch, James F.; Chiu, Ching‐Sang

doi:10.1029/2002jc001468

Cited by 65 publications

(94 citation statements)

References 23 publications

(52 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At all five transects, the maximum alongshore flow is seen at the shelf break, with the highest speed of 0.25 m s −1 . This is the shelfbreak jet, documented by earlier studies (e.g., Chen and He, 2010;Gawarkiewicz et al, 2001Gawarkiewicz et al, , 2004Linder and Gawarkiewicz, 1998). Mean cross-shelf velocity maps (Fig.…”

Section: Mean Velocity and Thermohaline Structurementioning

confidence: 72%

“…In another study on a large WCR in 2006, we found that, over a timescale of 1 week, the WCR can significantly change the cross-shelf exchange of water mass, heat and salt (Chen et al, 2014). Other work also reported the significant role of eddy activities in the cross-shelf exchange (e.g., Gawarkiewicz et al, 2001Gawarkiewicz et al, , 2004Joyce et al, 1992). Measuring the cross-shelf transport at these locations will therefore be very challenging.…”

Section: Mean Transportmentioning

confidence: 99%

“…For example, Joyce et al (1992) indicated that a single ring acting over a short time span (a couple of months) can account for the entire annual shelf-ocean transport and flux exchange. Shelfbreak frontal eddies associated with rings (e.g., Houghton et al, 1986), baroclinic instability and frontal meandering (Garvine et al, 1988;Gawarkiewicz et al, 2004) and topography and channels (e.g., Churchill et al, 1986;Ramp et al, 1985) also significantly affect the shelf-ocean exchange.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mean circulation in the coastal ocean off northeastern North America from a regional-scale ocean model

Chen

2015

Ocean Sci.

View full text Add to dashboard Cite

Abstract. A regional-scale ocean model was used to hindcast the coastal circulation over the Middle Atlantic Bight (MAB) and Gulf of Maine (GOM) from 2004 to 2013. The model was nested inside a data assimilative global ocean model that provided initial and open boundary conditions. Realistic atmospheric forcing, tides and observed river runoff were also used to drive the model. Hindcast solutions were compared against observations, which included coastal sea levels, satellite altimetry sea surface height, in situ temperature and salinity measurements in the GOM, and observed mean depth-averaged velocities. Good agreements with observations suggest that the hindcast model is capable of capturing the major circulation variability in the MAB and GOM. Time-and space-continuous hindcast fields were used to depict the mean circulation, along-and cross-shelf transport and the associated momentum balances. The hindcast confirms the presence of the equatorward mean shelf circulation, which varies from 2.33 Sv over the Scotian Shelf to 0.22 Sv near Cape Hatteras. Using the 200 m isobath as the shelf/slope boundary, the mean cross-shelf transport calculations indicate that the shelfbreak segments off the Gulf of Maine (including the southern flank of Georges Bank and the Northeast Channel) and Cape Hatteras are the major sites for shelf water export. The momentum analysis reveals that the along-shelf sea level difference from Nova Scotia to Cape Hatteras is about 0.36 m. The nonlinear advection, stress, and horizontal viscosity terms all contribute to the ageostrophic circulation in the along-isobath direction, whereas the nonlinear advection plays a dominant role in determining the ageostrophic current in the cross-isobath direction.

show abstract

Section: Mean Velocity and Thermohaline Structurementioning

confidence: 72%

Section: Mean Transportmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mean circulation in the coastal ocean off northeastern North America from a regional-scale ocean model

Chen

2015

Ocean Sci.

View full text Add to dashboard Cite

show abstract

“…The general circulation on the New England Shelf is part of the larger shelf circulation of the Middle Atlantic Bight, which is characterized by a southwestward along-shelf flow of relatively fresh water, with across-shelf offshore currents at the surface and bottom and onshore currents in the middle of the water column [57]. Shelf water is separated from saltier slope water by a shelf-slope front, but exchanges between these water types can occur due to frontal instabilities [31], eddies [30], warm-core ring shelf interactions [22,48], and saline intrusions at the seasonal pycnocline [56]. Locally, there is a counter-clockwise recirculation just south of MVCO, which is strongest in the summer months [50].…”

Section: Synechococcus Diversity At Mvcomentioning

confidence: 99%

Population dynamics and diversity of Synechococcus on the New England Shelf

Hunter-Cevera¹

2014

View full text Add to dashboard Cite

Synechococcus is a ubiquitous marine primary producer. Our understanding of the factors that determine its abundance has been limited by available observational tools, which have not been able to resolve population dynamics at timescales that match response times of cells (hours-days). Development of an automated flow cytometer (FlowCytobot) has enabled hourly observation of Synechococcus at the Martha's Vineyard Coastal Observatory (MVCO) since 2003. In order to ascribe changes in cell abundances to either growth or loss processes, information on division rate is needed. I refined a matrix population model that relates diel changes in the distribution of cell volume to division rate and demonstrated that it provides accurate estimates of daily division rate for both cultured and natural populations. Application of the model to the 11-year MVCO time series reveals that division rate is temperature limited during winter and spring, but light limited during fall. Inferred loss rates closely follow division rate in magnitude over the entire seasonal cycle, suggesting that losses are mainly generated by biological processes. While Synechococcus cell abundance, division rate, and loss rate demonstrate striking seasonal patterns, there are also significant shorter timescale variations and important multi-year trends that may be linked to climate. Interpretation of population dynamic patterns is complicated by the diversity found within marine Synechococcus, which is partitioned into 20 genetically distinct clades. Each clade may represent an ecotype, with a distinct ecological niche. To understand how diversity may affect population dynamics, I assessed the diversity at MVCO over annual cycles with culture-independent and dependent approaches. The population at MVCO is diverse, but dominated by clade I representatives throughout the year. Other clades were only found during summer and fall. High through-put sequencing of a diversity marker allowed a more quantitative investigation into these patterns. Five main Synechococcus oligotypes that comprise the population showed seasonal abundance patterns: peaking either during the spring bloom or during late summer and fall. This pattern strongly suggests that features of seasonal abundance are affected by the underlying diversity structure. Synechococcus abundance patterns result from a complex interplay among seasonal environmental changes, diversity, and biological losses.

show abstract

“…The undulations of the Scanfish were processed such that one up and one down cycle were averaged into a single vertical profile. Further details on the processing (for a SeaSoar vehicle) appear in Gawarkiewicz et al (2004). Horizontal spacing between profiles varied with water depth, but was typically between 0.5 and 2.0 km.…”

Section: Sampling Strategy and Methodsmentioning

confidence: 99%

Shelfbreak frontal structure and processes north of Cape Hatteras in winter

Gawarkiewicz¹,

Churchill²,

Bahr³

et al. 2008

j mar res

Self Cite

View full text Add to dashboard Cite

The circulation north of Cape Hatteras is complicated by the proximity of the shelfbreak front, the Gulf Stream, and convergent shelf flow from the Middle and South Atlantic Bights. A three-week cruise in this region in January/February, 2005 was undertaken in order to study the structure of the shelfbreak front as it terminates near Cape Hatteras and to quantify the freshwater transport from the Middle Atlantic Bight shelf into the Gulf Stream. Two strongly contrasting conditions were identified. Early in the cruise, the Gulf Stream directly abutted the shelfbreak at Cape Hatteras and drove a northward flow over the continental shelf as far north as 35°45ЈN. All of the Middle Atlantic Bight shelf water terminated by 35°30ЈN. Ten days later, the Gulf Stream had moved away from the shelfbreak south of Cape Hatteras and strong winds from the north were present. During this time, the shelfbreak frontal jet was strong (maximum southward velocity of approximately 0.5 m s Ϫ1 with a Rossby number of 2) and abruptly turned eastward and offshore between 35°35ЈN and 35°45ЈN. Freshwater transport eastward from the shelfbreak jet was 7.4 mSv and southward over the shelf was 19.9 mSv, giving a total freshwater transport of 27.3 mSv. This likely represents an upper bound due to the strong wind forcing. Implications of these results for the freshwater budget of the Middle Atlantic Bight shelf, stability properties of the shelfbreak front in this region, and the formation of "Ford water" in the Gulf Stream are discussed.

show abstract

A large‐amplitude meander of the shelfbreak front during summer south of New England: Observations from the Shelfbreak PRIMER experiment

Cited by 65 publications

References 23 publications

Mean circulation in the coastal ocean off northeastern North America from a regional-scale ocean model

Mean circulation in the coastal ocean off northeastern North America from a regional-scale ocean model

Population dynamics and diversity of Synechococcus on the New England Shelf

Shelfbreak frontal structure and processes north of Cape Hatteras in winter

Contact Info

Product

Resources

About