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Award Detail

Doing Business As Name:Woods Hole Oceanographic Institution
  • John M Toole
  • (508) 289-2531
  • Magdalena Andres
  • Terrence M Joyce
  • Michael S McCartney
  • Ruth G Curry
Award Date:12/16/2013
Estimated Total Award Amount: $ 1,545,515
Funds Obligated to Date: $ 1,545,515
  • FY 2014=$1,545,515
Start Date:03/01/2014
End Date:02/29/2020
Transaction Type:Grant
Awarding Agency Code:4900
Funding Agency Code:4900
CFDA Number:47.050
Primary Program Source:040100 NSF RESEARCH & RELATED ACTIVIT
Award Title or Description:Collaborative Research: Completing a 10-Year Record of Deep Western Boundary Current Observations at Line W: A Contribution to the Atlantic Meridional Overturning Circulation Study
Federal Award ID Number:1332667
DUNS ID:001766682
Parent DUNS ID:001766682
Program Officer:
  • Baris Uz
  • (703) 292-4557

Awardee Location

County:Woods Hole
Awardee Cong. District:09

Primary Place of Performance

Organization Name:Woods Hole Oceanographic Institution
Street:266 Woods Hole Rd.
City:Woods Hole
County:Woods Hole
Cong. District:09

Abstract at Time of Award

Overview: Over the last decade, a growing international research effort has focused attention on the physical state of the Atlantic Meridional Overturning Circulation (AMOC), including its climatically-vital transports of heat, mass and tracers, and the causes and consequences of its variability. Begun in 2004, the Line W program - moored and shipboard measurements of the equatorward-flowing Deep Western Boundary Current (DWBC) and poleward-flowing Gulf Stream along an altimeter track between New England and Bermuda has acquired a remarkable 10-year time series of this component of the AMOC. The goals of this project are to conduct a final Line W cruise to recover the current meter array presently in the water and reoccupy the hydrographic section, to process the recovered sensor data to final form and refurbish the sea-going equipment, and to complete the scientific analysis of the Line W data set in conjunction with fellow AMOC investigators. Intellectual Merit: Property and transport time series generated by several AMOC programs are now approaching or exceeding a decade in length and are starting to provide truly unprecedented views of the AMOC's structure, strength and variability. Synthesizing these results and combining them with state estimate models will undoubtedly result in improved understanding of the mechanics, dynamics and impacts of AMOC variability. Key foci of this project's analysis effort include careful quantification of the local variability at Line W, estimating variations in net (coast-to-coast) meridional transport of selected water masses by combining Line W observations with interior-ocean data and via models, and investigating the meridional coherence of water property anomalies and AMOC fluctuations by comparing Line-W observations with water property observations and AMOC estimates at other latitudes. Broader Impacts: A graduate student in the MIT/WHOI Joint Program will be funded to complete her Ph.D. thesis that will be based on Line W. As in past years, several students and/or postdocs will be involved in the final Line W cruise to gain hands-on experience with hydrographic sampling procedures and physical oceanographic mooring work. In this analysis and synthesis project, the original Line W investigators are entraining a new junior scientist into the research effort. This will introduce the investigator to new observational practices and associated data reduction and analysis procedures while bringing new expertise and viewpoints to the study. It is absolutely critical to observational physical oceanography that young investigators become fully versed in modern observational methods. The project's investigators will additionally continue to showcase Line W in public outreach events as a demonstration of ocean science and climate variation studies. Beyond these human elements, the Line W program is continuing to serve as a testbed for several emerging ocean measurement technologies and associated data processing procedures.

Publications Produced as a Result of this Research

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Andres, M., J. M. Toole, D. J. Torres, W. M. Smethie, Jr., T. M. Joyce and R. G. Curry "Stirring by deep cyclones and the evolution of Denmark Strait Overflow Water observed at Line W" Deep-Sea Research, v.109, 2016, p.10. doi:10.1016/j.dsr.2015.12.011 

Le Bras, I. A., I. Yashayaev and J. M. Toole "Tracking Labrador Sea Water property changes along the path of the Deep Western Boundary Current" In preparation, v., 2017, p..

Le Bras, I. A., M. Sonnewald and J. M. Toole "A vorticity budget for the Western North Atlantic based on observations" Journal of Physical Oceanography, v.49, 2019, p.2781. doi:10.1175/JPO-D-19-0111.1 

Evans, D.G., J. Toole, G. Forget, J.D. Zika, A.C. Naveira Garabato, A.J. George Nurser and L. Yu "Recent wind-driven changes in the Atlantic meridional overturning circulation" Journal of Physical Oceanography, v., 2017, p..

Huang, J., S.J. Manganini, JJ Park. D.B. Montluçon, J.M. Toole and T.I. Eglinton "Biological and physical controls on the flux and characteristics of sinking particles on the Northwest Atlantic margin" Journal of Geophysical Research, v., 2017, p..

Le Bras, I, S. Jayne and J. Toole "A model for the interaction between the Gulf Stream Northern Recirculation Gyre and the Deep Western Boundary Current" In preparation, v., 2017, p..

Andres, M. "On the recent destabilization of the Gulf Stream path downstream of Cape Hatteras" Geophysical Research Letters, v.43, 2016, p.9836. doi:10.1002/2016GL069966 

J. Forsyth, M. Andres, and G.G Gawarkiewicz "Recent accelerated warming of the continental shelf off New Jersey: Observations from the CMV Oleander expendable bathythermograph line." Journal of Geophysical Research, v.120, 2015, p.2370. doi:10.1002/2014JC010516 

Andres, A., K. A. Donohue, and J. M. Toole "The Gulf Stream’s path, time-averaged velocity structure and transport at 68.5˚W and 70.3˚W" Deep-Sea Research, Part I, v.156, 2020, p.. doi:10.1016/j.dsr.2019.103179 

Andres, M. J. M. Toole, D. Torres, W. M. Smethie, Jr., T. M. Joyce and R. G. Curry "Corrigendum to " Stirring by deep cyclones and the evolution of Denmark Strait Overflow Water observed at Line W."" Deep-Sea Research, v., 2017, p..

Project Outcomes Report


This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

The Line W research program was conceived to observe and characterize the time-averaged structure and intensity of the Deep Western Boundary Current (DWBC) and Gulf Stream, and to investigate the nature and causes of their variability.  These two oppositely-directed flows: the Gulf Stream carrying warm water northwards and the DWBC transporting cold water equatorward, are major contributors to the so-called Atlantic Meridional Overturning Circulation.   A long-term community research goal is to develop better understanding of the role of these time-varying circulations in earth?s climate system. The Line W study's approach centered around a sustained observational program that spanned the continental slope on a line running approximately from Woods Hole towards Bermuda.  The field program, that employed moored instruments, repeated ship-based sampling and analyses of remote sensing data, produced a 10-year-long time series of boundary current data that were (and continue to be be) used together with companion programs at other latitudes in the Atlantic to characterize the Meridional Overturning Circulation in the North Atlantic Ocean.  The field program ended in May 2014; the present grant supported the processing of the final set of recovered data and continued scientific analysis of the full 10 years of observations.  Highlights of the latter (reported in peer-reviewed journal articles) include quantifying the time averaged fluxes of water carried by the Gulf Stream and DWBC and a suggestion that these flows weakened by approximately 30% over the measurement period.  It is not known at this time if this finding reflects a decadal timescale oscillation that was not fully resolved by the 10-year observational program or manifests a sustained climate change.  In addition to the scientific research, the entire Line W program supported three (female) graduate students through to successful doctoral dissertation defenses, hosted many 10s of students and junior support staff on research cruises to gain sea going experience, and provided a testbed for several oceanographic sensors and measurement systems. 



Last Modified: 03/20/2020
Modified by: John M Toole

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