scholarly journals Decadal-Mean Impact of Including Ocean Surface Currents in Bulk Formulas on Surface Air–Sea Fluxes and Ocean General Circulation

2017 ◽  
Vol 30 (23) ◽  
pp. 9511-9525 ◽  
Author(s):  
Yang Wu ◽  
Xiaoming Zhai ◽  
Zhaomin Wang
Keyword(s):  
Wind Stress ◽  
General Circulation ◽  
Surface Wind ◽  
Ocean Surface ◽  
Meridional Overturning Circulation ◽  
Global Ocean ◽  
Turbulent Heat ◽  
Surface Currents ◽  
Ocean Surface Currents ◽  
Ocean General Circulation

The decadal-mean impact of including ocean surface currents in the bulk formulas on surface air–sea fluxes and the ocean general circulation is investigated for the first time using a global eddy-permitting coupled ocean–sea ice model. Although including ocean surface currents in air–sea flux calculations only weakens the surface wind stress by a few percent, it significantly reduces wind power input to both geostrophic and ageostrophic motions, and damps the eddy and mean kinetic energy throughout the water column. Furthermore, the strength of the horizontal gyre circulations and the Atlantic meridional overturning circulation are found to decrease considerably (by 10%–15% and ~13%, respectively). As a result of the weakened ocean general circulation, the maximum northward global ocean heat transport decreases by about 0.2 PW, resulting in a lower sea surface temperature and reduced surface heat loss in the northern North Atlantic. Additional sensitivity model experiments further demonstrate that it is including ocean surface currents in the wind stress calculation that dominates this decadal impact, with including ocean surface currents in the turbulent heat flux calculations making only a minor contribution. These results highlight the importance of properly accounting for ocean surface currents in surface air–sea fluxes in modeling the ocean circulation and climate.

An Adjoint Analysis of the Meridional Overturning Circulation in a Hybrid Coupled Model

2006 ◽  
Vol 19 (15) ◽  
pp. 3751-3767 ◽  
Author(s):  
Véronique Bugnion ◽  
Chris Hill ◽  
Peter H. Stone
Keyword(s):  
Boundary Conditions ◽  
Wind Stress ◽  
Ocean Circulation ◽  
General Circulation ◽  
Meridional Overturning Circulation ◽  
Global Ocean ◽  
Model Parameters ◽  
Overturning Circulation ◽  
Near Surface ◽  
Meridional Overturning

Abstract Multicentury sensitivities in a realistic geometry global ocean general circulation model are analyzed using an adjoint technique. This paper takes advantage of the adjoint model’s ability to generate maps of the sensitivity of a diagnostic (i.e., the meridional overturning’s strength) to all model parameters. This property of adjoints is used to review several theories, which have been elaborated to explain the strength of the North Atlantic’s meridional overturning. This paper demonstrates the profound impact of boundary conditions in permitting or suppressing mechanisms within a realistic model of the contemporary ocean circulation. For example, the so-called Drake Passage Effect in which wind stress in the Southern Ocean acts as the main driver of the overturning’s strength, is shown to be an artifact of boundary conditions that restore the ocean’s surface temperature and salinity toward prescribed climatologies. Advective transports from the Indian and Pacific basins play an important role in setting the strength of the overturning circulation under “mixed” boundary conditions, in which a flux of freshwater is specified at the ocean’s surface. The most “realistic” regime couples an atmospheric energy and moisture balance model to the ocean. In this configuration, inspection of the global maps of sensitivity to wind stress and diapycnal mixing suggests a significant role for near-surface Ekman processes in the Tropics. Buoyancy also plays an important role in setting the overturning’s strength, through direct thermal forcing near the sites of convection, or through the advection of salinity anomalies in the Atlantic basin.

Contrasting sources of variability in subtropical and subpolar Atlantic overturning

2020 ◽  
Author(s):  
Yavor Kostov ◽  
Helen L. Johnson ◽  
David P. Marshall ◽  
Gael Forget ◽  
Patrick Heimbach ◽  
...  
Keyword(s):  
Wind Stress ◽  
Ocean Circulation ◽  
Global Climate ◽  
Surface Wind ◽  
Circulation Model ◽  
Ocean Surface ◽  
Meridional Overturning Circulation ◽  
Surface Wind Stress ◽  
History Of ◽  
Meridional Overturning

<p><strong>The Atlantic meridional overturning circulation (AMOC) is pivotal for regional and global climate due to its key role in the uptake and redistribution of heat, carbon and other tracers. Establishing the causes of historical variability in the AMOC can tell us how the circulation responds to natural and anthropogenic changes at the ocean surface. However, attributing observed AMOC variability and inferring causal relationships is challenging because the circulation is influenced by multiple factors which co-vary and whose overlapping impacts can persist for years.  Here we reconstruct and unambiguously attribute variability in the AMOC at the latitudes of two observational arrays to the recent history of surface wind stress, temperature and salinity. We use a state-of-the-art technique that computes space- and time-varying sensitivity patterns of the AMOC strength with respect to multiple surface properties from a numerical ocean circulation model constrained by observations. While on inter-annual timescales, AMOC variability at 26°N is overwhelmingly dominated by a linear response to local wind stress, in contrast, AMOC variability at subpolar latitudes is generated by both wind stress and surface temperature and salinity anomalies. Our analysis allows us to obtain the first-ever reconstruction of subpolar AMOC from forcing anomalies at the ocean surface.</strong></p>

Coupling winds to ocean surface currents over the global ocean

2009 ◽  
Vol 29 (4) ◽  
pp. 261-268 ◽  
Author(s):  
Zengan Deng ◽  
Lian Xie ◽  
Bin Liu ◽  
Kejian Wu ◽  
Dongliang Zhao ◽  
...  
Keyword(s):  
Ocean Surface ◽  
Global Ocean ◽  
Surface Currents ◽  
Ocean Surface Currents

scholarly journals Using microwaves to map global ocean surface currents

Eos ◽  
2014 ◽  
Vol 95 (42) ◽  
pp. 388-388 ◽  
Author(s):  
Colin Schultz
Keyword(s):  
Ocean Surface ◽  
Global Ocean ◽  
Surface Currents ◽  
Ocean Surface Currents

The Impact of Ocean Surface Currents on Sverdrup Transport in the Midlatitude North Pacific via the Wind Stress Formulation

2017 ◽  
Vol 47 (3) ◽  
pp. 603-614 ◽  
Author(s):  
Zhitao Yu ◽  
E. Joseph Metzger ◽  
Yalin Fan
Keyword(s):  
Analytical Solution ◽  
Wind Stress ◽  
North Pacific ◽  
Reduction Rate ◽  
Ocean Surface ◽  
Surface Currents ◽  
The North ◽  
Ocean Surface Currents ◽  
Sverdrup Transport ◽  
The Kuroshio

AbstractA more complete wind stress τn formulation takes into account the ocean surface currents Vo, while the conventional wind stress τc popularly used in ocean circulation models is only a function of 10-m winds V10. An analytical solution is derived for the difference of Sverdrup transport induced by using τn instead of τc. A scaling analysis of the analytical solution indicates a 6% reduction of the Sverdrup transport in the North Pacific (i.e., the Kuroshio transport in the East China Sea) when Ekman velocity dominates the ocean surface currents. Because of the quadratic nature of wind stress, four nonlinear terms contribute equally to this difference: two vorticity torque terms and two speed gradient torque terms. A pair of 12.5-yr (July 2002–14) Hybrid Coordinate Ocean Model simulations that only differ in the wind stress formulation are used to test the analytical solution. The model results (2004–14) confirm that using τn instead of τc reduces the Sverdrup transport in the North Pacific by 8%–17% between 23° and 32°N. The reduction rate of the simulated 11-yr mean Kuroshio transport through the East Taiwan Channel and Tokara Strait is 8.0% (−2.5 Sv; 1 Sv ≡ 106 m3 s−1) and 12.8% (−4.8 Sv), respectively, in good agreement with the Sverdrup transport reduction rate, which is 7.4% (−2.6 Sv) and 15.4% (−6.3 Sv) at the corresponding latitude. The local effect of changing wind stress/wind work and Ekman transport due to the inclusion of Vo in the wind stress formulation is negligible compared to the Kuroshio volume transport change estimated in this study.

Sign in / Sign up

Export Citation Format

Share Document