Wind Stress Dependence on Ocean Surface Velocity: Implications for Mechanical Energy Input to Ocean Circulation

2006 ◽  
Vol 36 (2) ◽  
pp. 202-211 ◽  
Author(s):  
Thomas H. A. Duhaut ◽  
David N. Straub
Keyword(s):  
Wind Stress ◽  
Ocean Circulation ◽  
Energy Input ◽  
Mechanical Energy ◽  
Quadratic Function ◽  
Ocean Surface ◽  
Power Source ◽  
Surface Velocity ◽  
Stress Dependence ◽  
Scaling Arguments

Abstract It is pointed out that accounting for an ocean surface velocity dependence in the wind stress τ can lead to a significant reduction in the rate at which winds input mechanical energy to the geostrophic circulation. Specifically, the wind stress is taken to be a quadratic function of Ua − uo, where Ua and uo are the 10-m wind and ocean surface velocity, respectively. Because |Ua| is typically large relative to |uo|, accounting for a uo dependence leads only to relatively small changes in τ. The change to the basin-averaged wind power source, however, is considerably larger. Scaling arguments and quasigeostrophic simulations in a basin setting are presented. They suggest that the power source (or rate of energy input) is reduced by roughly 20%–35%.

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>

scholarly journals Reduction of near-inertial energy through the dependence of wind stress on the ocean-surface velocity

2013 ◽  
Vol 118 (6) ◽  
pp. 2761-2773 ◽  
Author(s):  
Willi Rath ◽  
Richard J. Greatbatch ◽  
Xiaoming Zhai
Keyword(s):  
Wind Stress ◽  
Ocean Surface ◽  
Surface Velocity ◽  
Inertial Energy

scholarly journals The Mechanical Energy Input to the Ocean Induced by Tropical Cyclones

2008 ◽  
Vol 38 (6) ◽  
pp. 1253-1266 ◽  
Author(s):  
Ling Ling Liu ◽  
Wei Wang ◽  
Rui Xin Huang
Keyword(s):  
Potential Energy ◽  
Tropical Cyclones ◽  
Wind Stress ◽  
Gravitational Potential ◽  
General Circulation ◽  
Energy Input ◽  
Mechanical Energy ◽  
Gravitational Potential Energy ◽  
Diapycnal Mixing ◽  
The Past

Abstract Wind stress and tidal dissipation are the most important sources of mechanical energy for maintaining the oceanic general circulation. The contribution of mechanical energy due to tropical cyclones can be a vitally important factor in regulating the oceanic general circulation and its variability. However, previous estimates of wind stress energy input were based on low-resolution wind stress data in which strong nonlinear events, such as tropical cyclones, were smoothed out. Using a hurricane–ocean coupled model constructed from an axisymmetric hurricane model and a three-layer ocean model, the rate of energy input to the world’s oceans induced by tropical cyclones over the period from 1984 to 2003 was estimated. The energy input is estimated as follows: 1.62 TW to the surface waves and 0.10 TW to the surface currents (including 0.03 TW to the near-inertial motions). The rate of gravitational potential energy increase due to tropical cyclones is 0.05 TW. Both the energy input from tropical cyclones and the increase of gravitational potential energy of the ocean show strong interannual and decadal variability with an increasing rate of 16% over the past 20 years. The annual mean diapycnal upwelling induced by tropical cyclones over the past 20 years is estimated as 39 Sv (Sv ≡ 106 m3 s−1). Owing to tropical cyclones, diapycnal mixing in the upper ocean (below the mixed layer) is greatly enhanced. Within the regimes of strong activity of tropical cyclones, the increase of diapycnal diffusivity is on the order of (1 − 6) × 10−4 m2 s−1. The tropical cyclone–related energy input and diapycnal mixing may play an important role in climate variability, ecology, fishery, and environments.

scholarly journals Surface currents and upwelling in Kerguelen Plateau regions

2014 ◽  
Vol 11 (5) ◽  
pp. 6845-6876 ◽  
Author(s):  
M. Zhou ◽  
Y. Zhu ◽  
F. d'Ovidio ◽  
Y.-H. Park ◽  
I. Durand ◽  
...  
Keyword(s):  
Wind Stress ◽  
Ocean Circulation ◽  
Surface Waters ◽  
World Ocean ◽  
Transport Processes ◽  
Surface Velocity ◽  
Kerguelen Plateau ◽  
Deep Basin ◽  
Wind Stress Curl ◽  
Kerguelen Islands

Abstract. Mean currents, horizontal diffusivity and upwelling on the Kerguelen Plateau and the deep basin east of the Kerguelen Islands were studied using 48 World Ocean Circulation Experiment (WOCE) Standard Surface Velocity Program (SVP) drifters deployed during the 2011 austral spring KEOPS II (KErguelen Ocean Plateau compared Study II) cruise. These drifter data were analyzed based on autocovariances for temporal scales, least-squares fitted streamfunctions for estimating mesoscale mean currents, wind stress fields and Ekman pumping, and Taylor's single particle diffusivity for estimating horizontal dispersion of surface waters. The results have revealed the shelfbreak current on the southern and eastern shelf slopes of the Kerguelen Islands, transport of surface waters from the Kerguelen–Heard shelf basin crossing the shelf slope into the deep basin off the plateau east of the Kerguelen Islands, and upwelling driven by wind stress curl in both the plateau and deep basin regions. The estimated volume transports off the Plateau in the upper 50 m based on surface drifters and below the mixed layer based on wind stress curl are 0.5 and 1.7 Sv, respectively, the mean and standard deviation of vertical velocities driven by wind stress curl averaged in the plateau and deep basin regions up to 3.2 ± 7.4 m d−1, and the upwelling fluxes in the surveyed plateau and deep basin regions are approximately 0.7 and 1.1 Sv, respectively. These physical transport processes can have significant effects on balances between biogeochemical elements and their recycling processes.

scholarly journals Double-diffusive mixing makes a small contribution to the global ocean circulation

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Carine G. van der Boog ◽  
Henk A. Dijkstra ◽  
Julie D. Pietrzak ◽  
Caroline A. Katsman
Keyword(s):  
Ocean Circulation ◽  
Mechanical Energy ◽  
Global Ocean ◽  
Small Contribution ◽  
Global Ocean Circulation ◽  
Diffusive Fluxes ◽  
Diffusive Mixing ◽  
Diffusive Processes ◽  
Flowing Waters ◽  
Double Diffusive

AbstractDouble-diffusive processes enhance diapycnal mixing of heat and salt in the open ocean. However, observationally based evidence of the effects of double-diffusive mixing on the global ocean circulation is lacking. Here we analyze the occurrence of double-diffusive thermohaline staircases in a dataset containing over 480,000 temperature and salinity profiles from Argo floats and Ice-Tethered Profilers. We show that about 14% of all profiles contains thermohaline staircases that appear clustered in specific regions, with one hitherto unknown cluster overlying the westward flowing waters of the Tasman Leakage. We estimate the combined contribution of double-diffusive fluxes in all thermohaline staircases to the global ocean’s mechanical energy budget as 7.5 GW [0.1 GW; 32.8 GW]. This is small compared to the estimated energy required to maintain the observed ocean stratification of roughly 2 TW. Nevertheless, we suggest that the regional effects, for example near Australia, could be pronounced.

scholarly journals The influence of the ocean circulation state on ocean carbon storage and CO<sub>2</sub> drawdown potential in an Earth system model

2017 ◽  
Author(s):  
Malin Ödalen ◽  
Jonas Nycander ◽  
Kevin I. C. Oliver ◽  
Laurent Brodeau ◽  
Andy Ridgwell
Keyword(s):  
Carbon Storage ◽  
Wind Stress ◽  
Ocean Circulation ◽  
System Model ◽  
Biological Pump ◽  
Earth System ◽  
Heat Diffusivity ◽  
Initial States ◽  
Ocean Carbon ◽  
Atmospheric Heat

Abstract. During the four most recent glacial cycles, atmospheric CO2 during glacial maxima has been lowered by about 90–100 ppm with respect to interglacials. There is widespread consensus that most of this carbon was partitioned in the ocean. It is however still debated which processes were dominant in achieving this increased carbon storage. In this paper, we use an Earth system model of intermediate complexity to constrain the range in ocean carbon storage for an ensemble of ocean circulation equilibrium states. We do a set of simulations where we run the model to pre-industrial equilibrium, but where we achieve different ocean circulation by changing forcing parameters such as wind stress, ocean diffusivity and atmospheric heat diffusivity. As a consequence, the ensemble members also have different ocean carbon reservoirs, global ocean average temperatures, biological pump efficiencies and conditions for air-sea CO2 disequilibrium. We analyse changes in total ocean carbon storage and separate it into contributions by the solubility pump, the biological pump and the CO2 disequilibrium component. We also relate these contributions to differences in strength of ocean overturning circulation. In cases with weaker circulation, we see that the ocean's capacity for carbon storage is larger. Depending on which ocean forcing parameter that is tuned, the origin of the change in carbon storage is different. When wind stress or ocean vertical diffusivity is changed, the response of the biological pump gives the most important effect on ocean carbon storage, whereas when atmospheric heat diffusivity or ocean horizontal diffusivity is changed, the solubility pump and the disequilibrium component are also important and sometimes dominant. Finally, we do a drawdown experiment, where we investigate the capacity for increased carbon storage by maximising the efficiency of the biological pump in our ensemble members. We conclude that different initial states for an ocean model result in different capacities for ocean carbon storage, due to differences in the ocean circulation state. This could explain why it is difficult to achieve comparable responses of the ocean carbon pumps in model intercomparison studies, where the initial states vary between models. The drawdown experiment highlights the importance of the strength of the biological pump in the control state for model studies of increased biological efficiency.

scholarly journals Response of North Atlantic Ocean Circulation to Atmospheric Weather Regimes

2014 ◽  
Vol 44 (1) ◽  
pp. 179-201 ◽  
Author(s):  
Nicolas Barrier ◽  
Christophe Cassou ◽  
Julie Deshayes ◽  
Anne-Marie Treguier
Keyword(s):  
Atlantic Ocean ◽  
Wind Stress ◽  
Ocean Circulation ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Meridional Overturning Circulation ◽  
Subpolar Gyre ◽  
Wind Stress Curl ◽  
Overturning Circulation ◽  
Weather Regimes

Abstract A new framework is proposed for investigating the atmospheric forcing of North Atlantic Ocean circulation. Instead of using classical modes of variability, such as the North Atlantic Oscillation (NAO) or the east Atlantic pattern, the weather regimes paradigm was used. Using this framework helped avoid problems associated with the assumptions of orthogonality and symmetry that are particular to modal analysis and known to be unsuitable for the NAO. Using ocean-only historical and sensitivity experiments, the impacts of the four winter weather regimes on horizontal and overturning circulations were investigated. The results suggest that the Atlantic Ridge (AR), negative NAO (NAO−), and positive NAO (NAO+) regimes induce a fast (monthly-to-interannual time scales) adjustment of the gyres via topographic Sverdrup dynamics and of the meridional overturning circulation via anomalous Ekman transport. The wind anomalies associated with the Scandinavian blocking regime (SBL) are ineffective in driving a fast wind-driven oceanic adjustment. The response of both gyre and overturning circulations to persistent regime conditions was also estimated. AR causes a strong, wind-driven reduction in the strengths of the subtropical and subpolar gyres, while NAO+ causes a strengthening of the subtropical gyre via wind stress curl anomalies and of the subpolar gyre via heat flux anomalies. NAO− induces a southward shift of the gyres through the southward displacement of the wind stress curl. The SBL is found to impact the subpolar gyre only via anomalous heat fluxes. The overturning circulation is shown to spin up following persistent SBL and NAO+ and to spin down following persistent AR and NAO− conditions. These responses are driven by changes in deep water formation in the Labrador Sea.

A new insight into ZIF-67 based triboelectric nanogenerator for self-powered robot object recognition

2021 ◽  
Author(s):  
Sugato Hajra ◽  
Manisha Sahu ◽  
Aneeta Manjari Padhan ◽  
Jaykishon Swain ◽  
Basanta Kumar Panigrahi ◽  
...  
Keyword(s):  
Object Recognition ◽  
Mechanical Energy ◽  
Power Source ◽  
Triboelectric Nanogenerator ◽  
Electrostatic Induction ◽  
Self Powered ◽  
Insight Into

Harvesting mechanical energy from surroundings can be a promising power source for micro/nano-devices. The triboelectric nanogenerator (TENG) works in the principle of triboelectrification and electrostatic induction. So far, the metals...

Detection of large-scale ocean circulation and tides

1983 ◽  
Vol 309 (1508) ◽  
pp. 361-370 ◽  
Keyword(s):  
Heat Flux ◽  
Surface Topography ◽  
Ocean Circulation ◽  
Satellite Altimetry ◽  
Large Scale ◽  
Precise Measurement ◽  
Ocean Surface ◽  
Ocean Topography ◽  
Tidal Signal ◽  
Nearly Continuous

As emphasized recently by Munk & Wunsch, the traditional methods of monitoring the ocean circulation give data too hopelessly aliased in space and time to permit a proper assessment of basin-wide dynamics and heat flux on climatic timescales. The prospect of nearly continuous recording of ocean-surface topography by satellite altimetry with suitable supporting measurements might make such assessments possible. The associated identification of the geocentric oceanic tidal signal in the data would be an additional bonus. The few weeks of altimetry recorded by Seasat gave a glimpse of the possibilities, but also clarified the areas where better precision and knowledge are needed. Further experience will be gained from currently projected multi-purpose satellites carrying altimeters, but serious knowledge of ocean circulation will result only from missions that are entirely dedicated to the precise measurement of ocean topography.

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