Tracing the flow of North Atlantic Deep Water using-chlorofluorocarbons

William M. Smethie, Rana A Fine, Alfred Putzka, E. Peter Jones

Research output: Contribution to journalArticle

119 Citations (Scopus)

Abstract

Chlorofluorocarbon (CFC) and hydrographic data collected in the North Atlantic in the late 1980s and early 1990s are used to confirm and add to earlier work on the large-scale circulation pathways and timescales for the spreading of North Atlantic Deep Water (NADW) components and how these components relate to the hydrographic structure. Throughout the western North Atlantic, high CFC concentrations are coincident with newly formed NADW components of Upper Labrador Sea Water (ULSW), Classical Labrador Sea Water (CLSW), and Overflow Waters (OW). ULSW is marked by a CFC maximum throughout the western subtropical and tropical Atlantic, and CLSW is marked by a CFC maximum north of 38° N in data collected in 1990-1992. Iceland-Scotland Overflow Water (ISOW) splits into two branches in the eastern basin, with one branch entering the western basin where it mixes with Denmark Strait Overflow Water (DSOW) and the densest branch flows southward along the bottom in the eastern basin. DSOW contributes the largest portion of the CFC signal in OW. It is estimated that these NADW components are at 60-75% equilibrium with the CFC concentration in the atmosphere at the time of formation. The large-scale data set confirms that NADW spreads southward by complex pathways involving advection in the Deep Western Boundary Current (DWBC), recirculation in deep gyres, and mixing. Maps of the CFC distribution show that properties within the gyres are relatively homogeneous, particularly for OW, and there is a profound change at the gyre boundaries. The density of the core of ULSW increases in the equatorward direction because of entrainment by overlying northward flowing Upper Circumpolar Water and at the equator, ULSW has the same density as CLSW in the subtropics but is warmer and saltier. The density of OW decreases between the subpolar region and the subtropics. This is caused by the least dense part of OW exiting the subpolar region in the DWBC, while the densest component recirculates in the subpolar basins. Some variability is observed in OW density in the subtropics and tropics because of variability in mixing with Antarctic Bottom Water and changes in the subtropics that are probably related to the transport of different vintages of DSOW. Ages derived from CFC ratios show that the NADW components of northern origin spread throughout the western North Atlantic within 25-30 years. This corresponds to a spreading rate of 1-2 cm s-1 and is comparable to the time a climate anomaly introduced into the subpolar North Atlantic will take to penetrate the entire western North Atlantic Ocean.

Original languageEnglish (US)
Article number1999JC900274
Pages (from-to)14297-14323
Number of pages27
JournalJournal of Geophysical Research C: Oceans
Volume105
Issue numberC6
StatePublished - Jun 15 2000

Fingerprint

Chlorofluorocarbons
chlorofluorocarbons
North Atlantic Deep Water
CFC
deep water
tracing
Labrador
sea water
Water
water
seawater
Denmark
straits
gyres
strait
western boundary current
basin
Antarctic Bottom Water
Scotland
Iceland

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Atmospheric Science
  • Astronomy and Astrophysics
  • Oceanography

Cite this

Smethie, W. M., Fine, R. A., Putzka, A., & Jones, E. P. (2000). Tracing the flow of North Atlantic Deep Water using-chlorofluorocarbons. Journal of Geophysical Research C: Oceans, 105(C6), 14297-14323. [1999JC900274].

Tracing the flow of North Atlantic Deep Water using-chlorofluorocarbons. / Smethie, William M.; Fine, Rana A; Putzka, Alfred; Jones, E. Peter.

In: Journal of Geophysical Research C: Oceans, Vol. 105, No. C6, 1999JC900274, 15.06.2000, p. 14297-14323.

Research output: Contribution to journalArticle

Smethie, WM, Fine, RA, Putzka, A & Jones, EP 2000, 'Tracing the flow of North Atlantic Deep Water using-chlorofluorocarbons', Journal of Geophysical Research C: Oceans, vol. 105, no. C6, 1999JC900274, pp. 14297-14323.
Smethie WM, Fine RA, Putzka A, Jones EP. Tracing the flow of North Atlantic Deep Water using-chlorofluorocarbons. Journal of Geophysical Research C: Oceans. 2000 Jun 15;105(C6):14297-14323. 1999JC900274.
Smethie, William M. ; Fine, Rana A ; Putzka, Alfred ; Jones, E. Peter. / Tracing the flow of North Atlantic Deep Water using-chlorofluorocarbons. In: Journal of Geophysical Research C: Oceans. 2000 ; Vol. 105, No. C6. pp. 14297-14323.
@article{e24597c677624b1f875cdf3d5ceb358d,
title = "Tracing the flow of North Atlantic Deep Water using-chlorofluorocarbons",
abstract = "Chlorofluorocarbon (CFC) and hydrographic data collected in the North Atlantic in the late 1980s and early 1990s are used to confirm and add to earlier work on the large-scale circulation pathways and timescales for the spreading of North Atlantic Deep Water (NADW) components and how these components relate to the hydrographic structure. Throughout the western North Atlantic, high CFC concentrations are coincident with newly formed NADW components of Upper Labrador Sea Water (ULSW), Classical Labrador Sea Water (CLSW), and Overflow Waters (OW). ULSW is marked by a CFC maximum throughout the western subtropical and tropical Atlantic, and CLSW is marked by a CFC maximum north of 38° N in data collected in 1990-1992. Iceland-Scotland Overflow Water (ISOW) splits into two branches in the eastern basin, with one branch entering the western basin where it mixes with Denmark Strait Overflow Water (DSOW) and the densest branch flows southward along the bottom in the eastern basin. DSOW contributes the largest portion of the CFC signal in OW. It is estimated that these NADW components are at 60-75{\%} equilibrium with the CFC concentration in the atmosphere at the time of formation. The large-scale data set confirms that NADW spreads southward by complex pathways involving advection in the Deep Western Boundary Current (DWBC), recirculation in deep gyres, and mixing. Maps of the CFC distribution show that properties within the gyres are relatively homogeneous, particularly for OW, and there is a profound change at the gyre boundaries. The density of the core of ULSW increases in the equatorward direction because of entrainment by overlying northward flowing Upper Circumpolar Water and at the equator, ULSW has the same density as CLSW in the subtropics but is warmer and saltier. The density of OW decreases between the subpolar region and the subtropics. This is caused by the least dense part of OW exiting the subpolar region in the DWBC, while the densest component recirculates in the subpolar basins. Some variability is observed in OW density in the subtropics and tropics because of variability in mixing with Antarctic Bottom Water and changes in the subtropics that are probably related to the transport of different vintages of DSOW. Ages derived from CFC ratios show that the NADW components of northern origin spread throughout the western North Atlantic within 25-30 years. This corresponds to a spreading rate of 1-2 cm s-1 and is comparable to the time a climate anomaly introduced into the subpolar North Atlantic will take to penetrate the entire western North Atlantic Ocean.",
author = "Smethie, {William M.} and Fine, {Rana A} and Alfred Putzka and Jones, {E. Peter}",
year = "2000",
month = "6",
day = "15",
language = "English (US)",
volume = "105",
pages = "14297--14323",
journal = "Journal of Geophysical Research: Oceans",
issn = "2169-9275",
publisher = "Wiley-Blackwell",
number = "C6",

}

TY - JOUR

T1 - Tracing the flow of North Atlantic Deep Water using-chlorofluorocarbons

AU - Smethie, William M.

AU - Fine, Rana A

AU - Putzka, Alfred

AU - Jones, E. Peter

PY - 2000/6/15

Y1 - 2000/6/15

N2 - Chlorofluorocarbon (CFC) and hydrographic data collected in the North Atlantic in the late 1980s and early 1990s are used to confirm and add to earlier work on the large-scale circulation pathways and timescales for the spreading of North Atlantic Deep Water (NADW) components and how these components relate to the hydrographic structure. Throughout the western North Atlantic, high CFC concentrations are coincident with newly formed NADW components of Upper Labrador Sea Water (ULSW), Classical Labrador Sea Water (CLSW), and Overflow Waters (OW). ULSW is marked by a CFC maximum throughout the western subtropical and tropical Atlantic, and CLSW is marked by a CFC maximum north of 38° N in data collected in 1990-1992. Iceland-Scotland Overflow Water (ISOW) splits into two branches in the eastern basin, with one branch entering the western basin where it mixes with Denmark Strait Overflow Water (DSOW) and the densest branch flows southward along the bottom in the eastern basin. DSOW contributes the largest portion of the CFC signal in OW. It is estimated that these NADW components are at 60-75% equilibrium with the CFC concentration in the atmosphere at the time of formation. The large-scale data set confirms that NADW spreads southward by complex pathways involving advection in the Deep Western Boundary Current (DWBC), recirculation in deep gyres, and mixing. Maps of the CFC distribution show that properties within the gyres are relatively homogeneous, particularly for OW, and there is a profound change at the gyre boundaries. The density of the core of ULSW increases in the equatorward direction because of entrainment by overlying northward flowing Upper Circumpolar Water and at the equator, ULSW has the same density as CLSW in the subtropics but is warmer and saltier. The density of OW decreases between the subpolar region and the subtropics. This is caused by the least dense part of OW exiting the subpolar region in the DWBC, while the densest component recirculates in the subpolar basins. Some variability is observed in OW density in the subtropics and tropics because of variability in mixing with Antarctic Bottom Water and changes in the subtropics that are probably related to the transport of different vintages of DSOW. Ages derived from CFC ratios show that the NADW components of northern origin spread throughout the western North Atlantic within 25-30 years. This corresponds to a spreading rate of 1-2 cm s-1 and is comparable to the time a climate anomaly introduced into the subpolar North Atlantic will take to penetrate the entire western North Atlantic Ocean.

AB - Chlorofluorocarbon (CFC) and hydrographic data collected in the North Atlantic in the late 1980s and early 1990s are used to confirm and add to earlier work on the large-scale circulation pathways and timescales for the spreading of North Atlantic Deep Water (NADW) components and how these components relate to the hydrographic structure. Throughout the western North Atlantic, high CFC concentrations are coincident with newly formed NADW components of Upper Labrador Sea Water (ULSW), Classical Labrador Sea Water (CLSW), and Overflow Waters (OW). ULSW is marked by a CFC maximum throughout the western subtropical and tropical Atlantic, and CLSW is marked by a CFC maximum north of 38° N in data collected in 1990-1992. Iceland-Scotland Overflow Water (ISOW) splits into two branches in the eastern basin, with one branch entering the western basin where it mixes with Denmark Strait Overflow Water (DSOW) and the densest branch flows southward along the bottom in the eastern basin. DSOW contributes the largest portion of the CFC signal in OW. It is estimated that these NADW components are at 60-75% equilibrium with the CFC concentration in the atmosphere at the time of formation. The large-scale data set confirms that NADW spreads southward by complex pathways involving advection in the Deep Western Boundary Current (DWBC), recirculation in deep gyres, and mixing. Maps of the CFC distribution show that properties within the gyres are relatively homogeneous, particularly for OW, and there is a profound change at the gyre boundaries. The density of the core of ULSW increases in the equatorward direction because of entrainment by overlying northward flowing Upper Circumpolar Water and at the equator, ULSW has the same density as CLSW in the subtropics but is warmer and saltier. The density of OW decreases between the subpolar region and the subtropics. This is caused by the least dense part of OW exiting the subpolar region in the DWBC, while the densest component recirculates in the subpolar basins. Some variability is observed in OW density in the subtropics and tropics because of variability in mixing with Antarctic Bottom Water and changes in the subtropics that are probably related to the transport of different vintages of DSOW. Ages derived from CFC ratios show that the NADW components of northern origin spread throughout the western North Atlantic within 25-30 years. This corresponds to a spreading rate of 1-2 cm s-1 and is comparable to the time a climate anomaly introduced into the subpolar North Atlantic will take to penetrate the entire western North Atlantic Ocean.

UR - http://www.scopus.com/inward/record.url?scp=0033664420&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0033664420&partnerID=8YFLogxK

M3 - Article

VL - 105

SP - 14297

EP - 14323

JO - Journal of Geophysical Research: Oceans

JF - Journal of Geophysical Research: Oceans

SN - 2169-9275

IS - C6

M1 - 1999JC900274

ER -