Lagrangian decomposition of the Deacon Cell

Döös, Kristofer; Nycander, Jonas; Coward, Andrew C.

doi:10.1029/2007jc004351

Cited by 69 publications

(84 citation statements)

References 28 publications

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“…These results are comparable to other model-based estimates (e.g. Maltrud and McClean, 2005;Kohl and Stammer, 2007;Doos et al, 2008), and to observational estimates in the North Atlantic (e.g. Cunningham et al, 2007).…”

Section: Zonally Averaged Fieldssupporting

confidence: 89%

Evaluation of a near-global eddy-resolving ocean model

et al. 2013

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Abstract. Analysis of the variability of the last 18 yr (1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012) of a 32 yr run of a new near-global, eddy-resolving ocean general circulation model coupled with biogeochemistry is presented. Comparisons between modelled and observed mean sea level (MSL), mixed layer depth (MLD), sea level anomaly (SLA), sea surface temperature (SST), and chlorophyll a indicate that the model variability is realistic. We find some systematic errors in the modelled MLD, with the model generally deeper than observations, which results in errors in the chlorophyll a, owing to the strong biophysical coupling. We evaluate several other metrics in the model, including the zonally averaged seasonal cycle of SST, meridional overturning, volume transports through key straits and passages, zonally averaged temperature and salinity, and El Niño-related SST indices. We find that the modelled seasonal cycle in SST is 0.5-1.5 • C weaker than observed; volume transports of the Antarctic Circumpolar Current, the East Australian Current, and Indonesian Throughflow are in good agreement with observational estimates; and the correlation between the modelled and observed NINO SST indices exceeds 0.91. Most aspects of the model circulation are realistic. We conclude that the model output is suitable for broader analysis to better understand upper ocean dynamics and ocean variability at mid-and low latitudes. The new model is intended to underpin a future version of Australia's operational short-range ocean forecasting system.

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Section: Zonally Averaged Fieldssupporting

confidence: 89%

Evaluation of a near-global eddy-resolving ocean model

et al. 2013

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“…This has been undertaken in previous studies, e.g. Döös et al (2008) decomposed the Deacon cell, whereas Kjellsson and Döös (2012) did the same for the Hadley and Ferrel cells. This method makes it possible to isolate specific regions and water masses.…”

Section: Simulationmentioning

confidence: 96%

“…This is done using Lagrangian trajectories simulated with the trajectory code TRACMASS (Döös et al, 2013). Using Lagrangian trajectories allows for analysing specific components of a larger circulation (Blanke et al, 1999;Döös et al, 2008;Thomas et al, 2015). In this study, they allow for separating water-mass transformations in the Atlantic Ocean from the rest of the world ocean in TS-space.…”

Section: Introductionmentioning

confidence: 99%

Lagrangian tracing of the water–mass transformations in the Atlantic Ocean

Berglund

Döös

Nycander

2017

Tellus A: Dynamic Meteorology and Oceanography

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The thermohaline stream function has previously been used to describe the ocean circulation in temperature and salinity space. In the present study, the Lagrangian thermohaline stream function is introduced and computed for northward flowing water masses in the Atlantic Ocean, using Lagrangian trajectories. The stream function shows the water-mass transformations in the Atlantic Ocean, where warm and saline water is converted to cold and fresh as it flows from 17 • S to 58 • N. By analysing the Lagrangian divergence of heat and salt flux, the conversion of temperature is found to take place in the Gulf Stream, the upper flank of the North Atlantic subtropical gyre and in the North Atlantic Drift, whereas the conversion of salinity rather occurs over a narrower band in the same regions. Thus, conversions of temperature and salinity as shown by the Lagrangian thermohaline stream function are confined to the same regions in the domain. The study of a specific, representative trajectory shows that, in the absence of air-sea interactions, a mixing process leads to the conversion of temperature and salinity from warm and saline to cold and fresh, and that this process is confined to the North Atlantic subtropical gyre. However, to define and to understand this process, further investigation is needed.

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“…Such spatial variation can be studied by using OGCMs instead of analysing discrete samples of tracers. One approach for this is the Lagrangian dispersion, where Lagrangian trajectories are computed from the velocity fields of an ocean circulation model (Johnson et al 2004;Dö ö s et al 2008). Another approach involves integrating the numerical ocean circulation model with passive tracers (Cox 1989;England 1995;Deleersnijder et al 2001;Deleersnijder et al 2002).…”

Section: Ocean Ventilation and Diagnosticsmentioning

confidence: 99%

A model study of the first ventilated regime of the Arctic Ocean during the early Miocene

Thompson¹,

Nilsson²,

Nycander³

et al. 2012

Polar Research

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The tectonic opening of Fram Strait during the Neogene was a significant geological event that transferred the Arctic Ocean from a poorly ventilated enclosed basin, with weak exchange with the North Atlantic, to a fully ventilated “ocean stage”. Previous tectonic and physical oceanographic analyses suggest that the early Miocene Fram Strait was likely several times narrower and less than half as deep as the present-day 400 km wide and 2550 m deep strait. Here we use an ocean general circulation model with a passive age tracer included to further address the effect of the Fram Strait opening on the early Miocene Arctic Ocean circulation. The model tracer age exhibits strong spatial gradient between the two major Arctic Ocean deep basins: the Eurasian and Amerasian basins. There is a two-layer stratification and the exchange flow through Fram Strait shows a bi-layer structure with a low salinity outflow from the Arctic confined to a relatively thin upper layer and a saline inflow from the North Atlantic below. Our study suggests that although Fram Strait was significantly narrower and shallower during early Miocene, and the ventilation mechanism quite different in our model, the estimated ventilation rates are comparable to the chemical tracer estimates in the present-day Arctic Ocean. Since we achieved ventilation of the Arctic Ocean with a prescribed Fram Strait width of 100 km and sill depth of 1000 m, ventilation may have preceded the timing of a full ocean depth connection between the Arctic Ocean and North Atlantic established through seafloor spreading and the development of the Lena Trough

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Lagrangian decomposition of the Deacon Cell

Cited by 69 publications

References 28 publications

Evaluation of a near-global eddy-resolving ocean model

Evaluation of a near-global eddy-resolving ocean model

Lagrangian tracing of the water–mass transformations in the Atlantic Ocean

A model study of the first ventilated regime of the Arctic Ocean during the early Miocene

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