On the North Atlantic Ocean Heat Content Change between 1955–70 and 1980–95

2012 ◽  
Vol 25 (10) ◽  
pp. 3619-3628 ◽  
Author(s):  
Xiaoming Zhai ◽  
Luke Sheldon
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Gulf Stream ◽  
Large Scale ◽  
North Atlantic Ocean ◽  
Heat Content ◽  
Ocean Heat Content ◽  
The North ◽  
Content Change ◽  
The North Atlantic

Abstract The upper-ocean heat content of the North Atlantic has undergone significant changes over the last 50 years but the underlying physical mechanisms are not yet well understood. In the present study, the authors examine the North Atlantic ocean heat content change in the upper 700 m between the 1955–70 and 1980–95 periods. Consistent with previous studies, the large-scale pattern consists of warming of the tropics and subtropics and cooling of the subpolar ocean. However, this study finds that the most significant heat content change in the North Atlantic during these two time periods is the warming of the Gulf Stream region. Numerical experiments strongly suggest that this warming in the Gulf Stream region is largely driven by changes of the large-scale wind forcing. Furthermore, the increased ocean heat content in the Gulf Stream region appears to feedback on to the atmosphere, resulting in warmer surface air temperature and enhanced precipitation there.

scholarly journals Analyzing the Influence of the North Atlantic Ocean Variability on the Atlantic Meridional Mode on Decadal Time Scales

Atmosphere ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 3
Author(s):  
Sandro F. Veiga ◽  
Emanuel Giarolla ◽  
Paulo Nobre ◽  
Carlos A. Nobre
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Decadal Variability ◽  
North Atlantic Ocean ◽  
Heat Content ◽  
Ocean Heat Content ◽  
Causality Analysis ◽  
Ocean Variability ◽  
The North ◽  
The North Atlantic

Important features of the Atlantic meridional mode (AMM) are not fully understood. We still do not know what determines its dominant decadal variability or the complex physical processes that sustain it. Using reanalysis datasets, we investigated the influence of the North Atlantic Ocean variability on the dominant decadal periodicity that characterizes the AMM. Statistical analyses demonstrated that the correlation between the sea surface temperature decadal variability in the Atlantic Ocean and the AMM time series characterizes the Atlantic multidecadal oscillation (AMO). This corroborates previous studies that demonstrated that the AMO precedes the AMM. A causal inference with a newly developed rigorous and quantitative causality analysis indicates that the AMO causes the AMM. To further understand the influence of the subsurface ocean on the AMM, the relationship between the ocean heat content (0–300 m) decadal variability and AMM was analyzed. The results show that although there is a significant zero-lag correlation between the ocean heat content in some regions of the North Atlantic (south of Greenland and in the eastern part of the North Atlantic) and the AMM, their cause-effect relationship on decadal time scales is unlikely. By correlating the AMO with the ocean heat content (0–300 m) decadal variability, the former precedes the latter; however, the causality analysis shows that the ocean heat content variability drives the AMO, corroborating several studies that point out the dominant role of the ocean heat transport convergence on AMO.

scholarly journals Assessment of an ensemble system that assimilates Jason-1/Envisat altimeter data in a probabilistic model of the North Atlantic ocean circulation

Ocean Science ◽  
2015 ◽  
Vol 11 (3) ◽  
pp. 425-438 ◽  
Author(s):  
G. Candille ◽  
J.-M. Brankart ◽  
P. Brasseur
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Gulf Stream ◽  
North Atlantic Ocean ◽  
Altimeter Data ◽  
Stochastic Perturbations ◽  
The North ◽  
Altimetric Data ◽  
The North Atlantic ◽  
Along Track

Abstract. A realistic circulation model of the North Atlantic ocean at 0.25° resolution (NATL025 NEMO configuration) has been adapted to explicitly simulate model uncertainties. This is achieved by introducing stochastic perturbations in the equation of state to represent the effect of unresolved scales on the model dynamics. The main motivation for this work is to develop ensemble data assimilation methods, assimilating altimetric data from past missions Jason-1 and Envisat. The assimilation experiment is designed to provide a description of the uncertainty associated with the Gulf Stream circulation for years 2005/2006, focusing on frontal regions which are predominantly affected by unresolved dynamical scales. An ensemble based on such stochastic perturbations is first produced and evaluated using along-track altimetry observations. Then each ensemble member is updated by a square root algorithm based on the SEEK (singular evolutive extended Kalman) filter (Brasseur and Verron, 2006). These three elements – stochastic parameterization, ensemble simulation and 4-D observation operator – are then used together to perform a 4-D analysis of along-track altimetry over 10-day windows. Finally, the results of this experiment are objectively evaluated using the standard probabilistic approach developed for meteorological applications (Toth et al., 2003; Candille et al., 2007). The results show that the free ensemble – before starting the assimilation process – correctly reproduces the statistical variability over the Gulf Stream area: the system is then pretty reliable but not informative (null probabilistic resolution). Updating the free ensemble with altimetric data leads to a better reliability with an information gain of around 30% (for 10-day forecasts of the SSH variable). Diagnoses on fully independent data (i.e. data that are not assimilated, like temperature and salinity profiles) provide more contrasted results when the free and updated ensembles are compared.

Changes in the probability of larvae crossing the North Atlantic during the 20th century

2019 ◽  
Vol 70 (8) ◽  
pp. 1150 ◽  
Author(s):  
Laura Rodríguez-Díaz ◽  
Inés Álvarez ◽  
Moncho Gómez-Gesteira ◽  
Fran Santos
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Gulf Stream ◽  
North Atlantic Ocean ◽  
Past Century ◽  
Straits Of Florida ◽  
The North ◽  
Ocean Data Assimilation ◽  
The North Atlantic ◽  
Passive Tracers

Lagrangian trajectories of passive particles were simulated using velocity fields provided by the Simple Ocean Data Assimilation model to determine changes in their probability of crossing the North Atlantic Ocean during the period 1899–2010. Particles were released in the Straits of Florida, where the Gulf Stream is the main driving force. The results showed that eddy kinetic energy increased along the Gulf Stream path, which enhanced connectivity across the Atlantic. The time for water parcels (passive tracers) to cross the North Atlantic Ocean has shortened in the past century, with a minimum crossing period of 6–7 months and a decreasing trend ranging from –0.15 to –0.40 months per decade.

Detection and characterization of SCVs in the North Atlantic

2020 ◽  
Author(s):  
Ashwita Chouksey ◽  
Xavier Carton ◽  
Jonathan Gula
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Large Scale ◽  
North Atlantic Ocean ◽  
The North ◽  
Place Of Origin ◽  
Different Depths ◽  
The North Atlantic ◽  
Transport And Mixing

<p>In recent years, the oceanographic community has devoted considerable interest to the study of SCVs (Submesoscale Coherent Vortices, i.e. vortices with radii between 2-30 km, below the first internal radius of deformation); indeed, both mesoscale and submesoscale eddies contribute to the transport and mixing of water masses and of tracers (active and passive), affecting the heat transport, the ventilation pathways and thus having an impact on the large scale circulation.</p><p>In different areas of the ocean, SCVs have been detected, via satellite or in-situ measurements, at the surface or at depth. From these data, SCVs were found to be of different shapes and sizes depending on their place of origin and on their location. Here, we will concentrate rather on the SCVs at depth.</p><p>In this study, we use a high resolution simulation of the North Atlantic ocean with the ROMS-CROCO model. In this simulation, we also identify the SCVs at different depths and densities; we analyse their site and mechanism of generation, their drift, the physical processes conducting to this drift and their interactions with the surrounding flows. We also quantify their physical characteristics (radius, thickness, intensity/vorticity, bias in polarity: cyclones versus anticyclones). We provide averages for these characteristics and standard deviations. </p><p>We compare the model results with the observational data, in particular temperature and salinity profiles from Argo floats and velocity data from currentmeter recordings. </p><p>This study is a first step in the understanding of the formation, occurrences and structure of SCVs in the North Atlantic Ocean, of help to improve their in-situ sampling.</p>

scholarly journals Heat content variability in the North Atlantic Ocean in ocean reanalyses

2015 ◽  
Vol 42 (8) ◽  
pp. 2901-2909 ◽  
Author(s):  
Sirpa Häkkinen ◽  
Peter B. Rhines ◽  
Denise L. Worthen
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Heat Content ◽  
The North ◽  
Ocean Reanalyses ◽  
The North Atlantic

scholarly journals III. The circulation of the surface waters of the north atlantic ocean

1901 ◽  
Vol 196 (274-286) ◽  
pp. 61-203 ◽  
Keyword(s):  
Atlantic Ocean ◽  
North Atlantic ◽  
Surface Waters ◽  
Gulf Stream ◽  
North Atlantic Ocean ◽  
Critical Examination ◽  
Northern Latitude ◽  
The North ◽  
History Of ◽  
The North Atlantic

The history of our knowledge of the currents of the North Atlantic Ocean up to the year 1870 has been written once for all by Petermann (I), who in that year published a memoir maintaining, contrary to the opinion of Findlay, Blunt, and Carpenter, that eastern and northern extensions of the Gulf Stream were the prime factors in the circulation. Petermann subjected practically the whole of the material in the way of observations then extant to an exhaustive critical examination, and came to conclusions which are worth quoting, in the summary, inasmuch as the observations of the twenty succeeding years did not seriously modify them :— 1. The hot source and core of the Gulf Stream extends from the Strait of Florida, along the North American coast at all times.... up to the 37th degree of northern latitude.

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