Seasonal Variability of the Atlantic Meridional Overturning Circulation at 26.5°N

Kanzow, Torsten; Cunningham, Stuart A.; Johns, William E.; Hirschi, Joël; Marotzke, Jochem; Baringer, Molly O.; Meinen, Christopher S.; Chidichimo, María Paz; Atkinson, C. P.; Beal, Lisa M.; Bryden, Harry L.; Collins, Jennifer

doi:10.1175/2010jcli3389.1

Cited by 285 publications

(411 citation statements)

References 61 publications

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“…The North Atlantic Deep Water (NADW) cell of the AMOC peaks at 17.0 Sv (1 Sv = 10 6 m 3 s −1 ) at 32.5 • N and a depth of 1020 m. This agrees with the estimate of 16 ± 2 Sv from Ganachaud (2003) and recent measurements of 18.7±2 Sv at 26.5 • N (Kanzow et al, 2010). The NADW is formed south of Greenland and in the Nordic seas (Fig.…”

Section: The Pre-industrial Oceansupporting

confidence: 86%

Coupled ice sheet–climate modeling under glacial and pre-industrial boundary conditions

2014

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Abstract. In the standard Paleoclimate Modelling Intercomparison Project (PMIP) experiments, the Last Glacial Maximum (LGM) is modeled in quasi-equilibrium with atmosphere-ocean-vegetation general circulation models (AOVGCMs) with prescribed ice sheets. This can lead to inconsistencies between the modeled climate and ice sheets. One way to avoid this problem would be to model the ice sheets explicitly. Here, we present the first results from coupled ice sheet-climate simulations for the pre-industrial times and the LGM.Our setup consists of the AOVGCM ECHAM5/MPIOM/LPJ bidirectionally coupled with the Parallel Ice Sheet Model (PISM) covering the Northern Hemisphere. The results of the pre-industrial and LGM simulations agree reasonably well with reconstructions and observations. This shows that the model system adequately represents large, non-linear climate perturbations.A large part of the drainage of the ice sheets occurs in ice streams. Most modeled ice stream systems show recurring surges as internal oscillations. The Hudson Strait Ice Stream surges with an ice volume equivalent to about 5 m sea level and a recurrence interval of about 7000 yr. This is in agreement with basic expectations for Heinrich events. Under LGM boundary conditions, different ice sheet configurations imply different locations of deep water formation.

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Section: The Pre-industrial Oceansupporting

confidence: 86%

Coupled ice sheet–climate modeling under glacial and pre-industrial boundary conditions

2014

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“…In comparison, Kanzow et al [2010] derive 18.7˙2.1 Sv from observations. We conclude that an increased zonal diffusivity improves the model, but expressed as global metrics, does little to change the physics.…”

Section: Resultsmentioning

confidence: 92%

Effects of increased isopycnal diffusivity mimicking the unresolved equatorial intermediate current system in an earth system climate model

Getzlaff

Dietze

2013

Geophysical Research Letters

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Earth system climate models generally underestimate dissolved oxygen concentrations in the deep eastern equatorial Pacific. This problem is associated with the “nutrient trapping” problem, described by Najjar et al. [1992], and is, at least partially, caused by a deficient representation of the Equatorial Intermediate Current System (EICS). Here we emulate the unresolved EICS in the UVic earth system climate model by locally increasing the zonal isopycnal diffusivity. An anisotropic diffusivity of ∼50,000 m2 s−1 yields an improved global representation of temperature, salinity and oxygen. In addition, it (1) resolves most of the local “nutrient trapping” and associated oxygen deficit in the eastern equatorial Pacific and (2) reduces spurious zonal temperature gradients on isopycnals without affecting other physical metrics such as meridional overturning or air‐sea heat fluxes. Finally, climate projections of low‐oxygenated waters and associated denitrification change sign and apparently become more plausible.

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“…590 Y. Fu et al: AMOC at 14.5 • N and 24.5 • N MOCHA-WBTS, hereafter RAPID) have shown that the AMOC exhibits variability on timescales from seasonal to decadal (Cunningham et al, 2007;Kanzow et al, 2008Kanzow et al, , 2010Smeed et al, 2014). At 26 • N, different components of the AMOC have been analyzed in detail including the western boundary current (Florida Current), the Ekman transport, and the interior geostrophic transport.…”

Section: Introductionmentioning

confidence: 99%

“…At 26 • N, different components of the AMOC have been analyzed in detail including the western boundary current (Florida Current), the Ekman transport, and the interior geostrophic transport. Based on the RAPID array data, Cunningham et al (2007) reported that on subseasonal timescales, the upper ocean has an immediate response to the change in the Ekman transport, while Kanzow et al (2010) showed that on seasonal timescales, the wind stress curl near the eastern boundary plays a dominant role in modulating the strength of the AMOC. Interestingly, studies based on the RAPID array at 26 • N and on the MOVE array at 16 • N often reveal contrary conclusions on the AMOC.…”

Section: Introductionmentioning

confidence: 99%

Atlantic Meridional Overturning Circulation at 14.5° N in 1989 and 2013 and 24.5° N in 1992 and 2015: volume, heat, and freshwater transports

Karstensen

Brandt

2018

Ocean Sci.

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Seasonal Variability of the Atlantic Meridional Overturning Circulation at 26.5°N

Abstract: The Atlantic meridional overturning circulation (AMOC) makes the strongest oceanic contribution to the me ridional redistribution of heat. Here, an observation-based, fortyeight-month-long time series of the vertical structure and strength of the AMOC at 26.5°N

Cited by 285 publications

References 61 publications

Coupled ice sheet–climate modeling under glacial and pre-industrial boundary conditions

Coupled ice sheet–climate modeling under glacial and pre-industrial boundary conditions

Effects of increased isopycnal diffusivity mimicking the unresolved equatorial intermediate current system in an earth system climate model

Atlantic Meridional Overturning Circulation at 14.5° N in 1989 and 2013 and 24.5° N in 1992 and 2015: volume, heat, and freshwater transports

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