Effect of the air-sea heat flux on the North Atlantic circulation and the Gulf Stream system.

1995 ◽  
Author(s):  
Tamay M. Özgökmen
Keyword(s):  
Heat Flux ◽  
North Atlantic ◽  
Gulf Stream ◽  
The North ◽  
Stream System ◽  
The North Atlantic

Air–Sea Fluxes over the Gulf Stream Region: Atmospheric Controls and Trends

2010 ◽  
Vol 23 (10) ◽  
pp. 2651-2670 ◽  
Author(s):  
Jeffrey Shaman ◽  
R. M. Samelson ◽  
Eric Skyllingstad
Keyword(s):  
Heat Flux ◽  
Latent Heat ◽  
North Atlantic ◽  
Gulf Stream ◽  
Heat Fluxes ◽  
High Flux ◽  
Mode Water ◽  
The North ◽  
Storm Frequency ◽  
The North Atlantic

Abstract The intraseasonal variability of turbulent surface heat fluxes over the Gulf Stream extension and subtropical mode water regions of the North Atlantic, and long-term trends in these fluxes, are explored using NCEP–NCAR reanalysis. Wintertime sensible and latent heat fluxes from these surface waters are characterized by episodic high flux events due to cold air outbreaks from North America. Up to 60% of the November–March (NDJFM) total sensible heat flux and 45% of latent heat flux occurs on these high flux days. On average 41% (34%) of the total NDJFM sensible (latent) heat flux takes place during just 17% (20%) of the days. Over the last 60 years, seasonal NDJFM sensible and latent heat fluxes over the Climate Variability and Predictability (CLIVAR) Mode Water Dynamic Experiment (CLIMODE) region have increased owing to an increased number of high flux event days. The increased storm frequency has altered average wintertime temperature conditions in the region, producing colder surface air conditions over the North American eastern seaboard and Labrador Sea and warmer temperatures over the Sargasso Sea. These temperature changes have increased low-level vertical wind shear and baroclinicity along the North Atlantic storm track over the last 60 years and may further favor the trend of increasing storm frequency over the Gulf Stream extension and adjacent region.

33.—A Review of the Branching of the Gulf Stream System

1972 ◽  
Vol 72 (1) ◽  
pp. 341-349 ◽  
Author(s):  
C. R. Mann
Keyword(s):  
North Atlantic ◽  
Gulf Stream ◽  
Good Evidence ◽  
Water Masses ◽  
North Atlantic Current ◽  
The North ◽  
Dynamic Computation ◽  
Stream System ◽  
The North Atlantic ◽  
Atlantic Current

SynopsisThe surveys of temperature and salinity that have led to the concept that the Gulf Stream splits into branches are reviewed, beginning with the survey made by Helland-Hansen on board the Michael Sars in 1910. The system of currents, or branches, between the Newfoundland Banks and the Mid- Atlantic deduced by the different investigations from charts of temperature, or by dynamic computation, are not all compatible. There is good evidence that part of the Gulf Stream turns south-east after passing the Newfoundland Banks and part turns north to become the North Atlantic Current. Both these currents are boundaries between water masses in the upper layer of the ocean. The evidence for permanent currents other than these two is conflicting.

scholarly journals The North Atlantic Eddy Heat Transport and Its Relation with the Vertical Tilting of the Gulf Stream Axis

2017 ◽  
Vol 47 (6) ◽  
pp. 1281-1289 ◽  
Author(s):  
A. M. Treguier ◽  
C. Lique ◽  
J. Deshayes ◽  
J. M. Molines
Keyword(s):  
Numerical Model ◽  
Heat Transport ◽  
North Atlantic ◽  
Gulf Stream ◽  
Mean Flow ◽  
The North ◽  
Spatial Shift ◽  
Eddy Heat Flux ◽  
Eddy Heat Transport ◽  
The North Atlantic

AbstractCorrelations between temperature and velocity fluctuations are a significant contribution to the North Atlantic meridional heat transport, especially at the northern boundary of the subtropical gyre. In satellite observations and in a numerical model at ⅞° resolution, a localized pattern of positive eddy heat flux is found northwest of the Gulf Stream, downstream of its separation at Cape Hatteras. It is confined to the upper 500 m. A simple kinematic model of a meandering jet can explain the surface eddy flux, taking into account a spatial shift between the maximum velocity of the jet and the maximum cross-jet temperature gradient. In the Gulf Stream such a spatial shift results from the nonlinear temperature profile and the vertical tilting of the velocity profile with depth. The numerical model suggests that the meandering of the Gulf Stream could account, at least in part, for the large eddy heat transport (of order 0.3 PW) near 36°N in the North Atlantic and for its compensation by the mean flow.

scholarly journals Forecasting the Gulf Stream Path using Buoyancy and Wind Forcing over the North Atlantic

2021 ◽  
Author(s):  
Adrienne Silver ◽  
Avijit Gangopadhyay ◽  
Glen Gawarkiewicz ◽  
Arnold Taylor ◽  
Alejandra Sanchez‐Franks
Keyword(s):  
North Atlantic ◽  
Gulf Stream ◽  
Wind Forcing ◽  
The North ◽  
The North Atlantic

scholarly journals The Life Cycle of the North Atlantic Storm Track*

2015 ◽  
Vol 72 (2) ◽  
pp. 821-833 ◽  
Author(s):  
Lenka Novak ◽  
Maarten H. P. Ambaum ◽  
Rémi Tailleux
Keyword(s):  
Heat Flux ◽  
Life Cycle ◽  
North Atlantic ◽  
Storm Track ◽  
High Heat ◽  
High Heat Flux ◽  
Dominant Type ◽  
The North ◽  
Eddy Heat Flux ◽  
The North Atlantic

Abstract The North Atlantic eddy-driven jet exhibits latitudinal variability with evidence of three preferred latitudinal locations: south, middle, and north. Here the authors examine the drivers of this variability and the variability of the associated storm track. The authors investigate the changes in the storm-track characteristics for the three jet locations and propose a mechanism by which enhanced storm-track activity, as measured by upstream heat flux, is responsible for cyclical downstream latitudinal shifts in the jet. This mechanism is based on a nonlinear oscillator relationship between the enhanced meridional temperature gradient (and thus baroclinicity) and the meridional high-frequency (periods of shorter than 10 days) eddy heat flux. Such oscillations in baroclinicity and heat flux induce variability in eddy anisotropy, which is associated with the changes in the dominant type of wave breaking and a different latitudinal deflection of the jet. The authors’ results suggest that high heat flux is conducive to a northward deflection of the jet, whereas low heat flux is conducive to a more zonal jet. This jet-deflecting effect was found to operate most prominently downstream of the storm-track maximum, while the storm track and the jet remain anchored at a fixed latitudinal location at the beginning of the storm track. These cyclical changes in storm-track characteristics can be viewed as different stages of the storm track’s spatiotemporal life cycle.

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.

scholarly journals Observational Assessment of Nonlocal Heat Flux Feedback in the North Atlantic by GEFA

2013 ◽  
Vol 52 (3) ◽  
pp. 645-653 ◽  
Author(s):  
Na Wen ◽  
Zhengyu Liu ◽  
Qinyu Liu
Keyword(s):  
Heat Flux ◽  
North Atlantic ◽  
Surface Wind ◽  
Turbulent Heat ◽  
Observational Assessment ◽  
The North ◽  
The North Atlantic ◽  
Flux Response ◽  
Sst Anomalies ◽  
Heat Flux Feedback

AbstractMost previous studies have proven the local negative heat flux feedback (the surface heat flux response to SST anomalies) in the midlatitude areas. However, it is uncertain whether a nonlocal heat flux feedback can be observed. In this paper, the generalized equilibrium feedback assessment (GEFA) method is employed to examine the full surface turbulent heat flux response to SST in the North Atlantic Ocean using NCEP–NCAR reanalysis data. The results not only confirm the dominant local negative feedback, but also indicate a robust nonlocal positive feedback of the Gulf Stream Extension (GSE) SST to the downstream heat flux in the subpolar region. This nonlocal feedback presents a strong seasonality, with response magnitudes of in winter and in summer. Further study indicates that the nonlocal effect is initiated by the adjustments of the downstream surface wind to the GSE SST anomalies.

scholarly journals Persistent Atmospheric and Oceanic Anomalies in the North Atlantic from Summer 2009 to Summer 2010

2011 ◽  
Vol 24 (22) ◽  
pp. 5812-5830 ◽  
Author(s):  
Zeng-Zhen Hu ◽  
Arun Kumar ◽  
Bohua Huang ◽  
Yan Xue ◽  
Wanqiu Wang ◽  
...  
Keyword(s):  
Heat Flux ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
Negative Phase ◽  
Atlantic Basin ◽  
Term Trend ◽  
The North ◽  
The North Atlantic ◽  
Long Term Trend

Abstract In this work, the authors analyze the air–sea interaction processes associated with the persistent atmospheric and oceanic anomalies in the North Atlantic Ocean during summer 2009–summer 2010 with a record-breaking positive sea surface temperature anomaly (SSTA) in the hurricane Main Development Region (MDR) in the spring and summer of 2010. Contributions to the anomalies from the El Niño–Southern Oscillation (ENSO), the North Atlantic Oscillation (NAO), and a long-term trend are identified. The warming in the tropical North Atlantic during summer 2009–summer 2010 represented a typical response to ENSO, preconditioned and amplified by the influence of a strong and persistent negative phase of the NAO. The long-term trends enhanced the warming in the high and low latitudes and weakened the cooling in the midlatitudes. The persistent negative phase of the NAO was associated with active thermodynamic air–sea interaction in the North Atlantic basin. Surface wind anomalies associated with the NAO altered the ocean surface heat flux and changed the SSTA, which was likely further enhanced by the positive wind speed–evaporation–SST feedback. The total heat flux was dominated by the latent and sensible heat fluxes, while the shortwave radiation contributed to the tropical SSTA to a lesser degree. Sensitivity experiments with an atmospheric general circulation model forced by observed SST in the Atlantic Ocean alone suggested that the Atlantic SSTA, which was partly forced by the NAO, had some positive contribution to the persistence of the negative phase of the NAO. Therefore, the persistent NAO condition is partly an outcome of the global climate anomalies and the ocean–atmosphere feedback within the Atlantic basin. The combination of the ENSO, NAO, and long-term trend resulted in the record-breaking positive SSTA in the MDR in the boreal spring and summer of 2010. On the basis of the statistical relationship, the SSTA pattern in the North Atlantic was reasonably well predicted by using the preceding ENSO and NAO as predictors.

scholarly journals Instability-Driven Benthic Storms below the Separated Gulf Stream and the North Atlantic Current in a High-Resolution Ocean Model

2018 ◽  
Vol 48 (10) ◽  
pp. 2283-2303 ◽  
Author(s):  
René Schubert ◽  
Arne Biastoch ◽  
Meghan F. Cronin ◽  
Richard J. Greatbatch
Keyword(s):  
Energy Transfer ◽  
High Resolution ◽  
Kinetic Energy ◽  
North Atlantic ◽  
Gulf Stream ◽  
Eddy Kinetic Energy ◽  
North Atlantic Current ◽  
The North ◽  
The North Atlantic ◽  
Atlantic Current

AbstractBenthic storms are important for both the energy budget of the ocean and for sediment resuspension and transport. Using 30 years of output from a high-resolution model of the North Atlantic, it is found that most of the benthic storms in the model occur near the western boundary in association with the Gulf Stream and the North Atlantic Current, in regions that are generally collocated with the peak near-bottom eddy kinetic energy. A common feature is meander troughs in the near-surface jets that are accompanied by deep low pressure anomalies spinning up deep cyclones with near-bottom velocities of up to more than 0.5 m s−1. A case study of one of these events shows the importance of both baroclinic and barotropic instability of the jet, with energy being extracted from the jet in the upstream part of the meander trough and partly returned to the jet in the downstream part of the meander trough. This motivates examining the 30-yr time mean of the energy transfer from the (annual mean) background flow into the eddy kinetic energy. This quantity is shown to be collocated well with the region in which benthic storms and large increases in deep cyclonic relative vorticity occur most frequently, suggesting an important role for mixed barotropic–baroclinic instability-driven cyclogenesis in generating benthic storms throughout the model simulation. Regions of the largest energy transfer and most frequent benthic storms are found to be the Gulf Stream west of the New England Seamounts and the North Atlantic Current near Flemish Cap.

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