scholarly journals Intercomparison of the Charnock and COARE bulk wind stress formulations for coastal ocean modelling

Ocean Science ◽  
2013 ◽  
Vol 9 (4) ◽  
pp. 721-729 ◽  
Author(s):  
J. M. Brown ◽  
L. O. Amoudry ◽  
F. M. Mercier ◽  
A. J. Souza
Keyword(s):  
Wind Stress ◽  
Ocean Circulation ◽  
Stress Component ◽  
Surface Wind ◽  
Acoustic Doppler Current Profiler ◽  
Coastal Ocean ◽  
Surface Mixed Layer ◽  
Residual Circulation ◽  
Surface Wind Stress ◽  
Charnock Relation

Abstract. The accurate parameterisation of momentum and heat transfer across the air–sea interface is vital for realistic simulation of the atmosphere–ocean system. In most modelling applications accurate representation of the wind stress is required to numerically reproduce surge, coastal ocean circulation, surface waves, turbulence and mixing. Different formulations can be implemented and impact the accuracy of the instantaneous and long-term residual circulation, the surface mixed layer, and the generation of wave-surge conditions. This, in turn, affects predictions of storm impact, sediment pathways, and coastal resilience to climate change. The specific numerical formulation needs careful selection to ensure the accuracy of the simulation. Two wind stress parameterisations widely used in the ocean circulation and the storm surge communities respectively are studied with focus on an application to the NW region of the UK. Model–observation validation is performed at two nearshore and one estuarine ADCP (acoustic Doppler current profiler) stations in Liverpool Bay, a hypertidal region of freshwater influence (ROFI) with vast intertidal areas. The period of study covers both calm and extreme conditions to test the robustness of the 10 m wind stress component of the Coupled Ocean–Atmosphere Response Experiment (COARE) bulk formulae and the standard Charnock relation. In this coastal application a realistic barotropic–baroclinic simulation of the circulation and surge elevation is set-up, demonstrating greater accuracy occurs when using the Charnock relation, with a constant Charnock coefficient of 0.0185, for surface wind stress during this one month period.

scholarly journals Intercomparison of the Charnock and CORE bulk wind stress formulations for coastal ocean modelling

2013 ◽  
Vol 10 (2) ◽  
pp. 519-537 ◽  
Author(s):  
J. M. Brown ◽  
L. O. Amoudry ◽  
F. M. Mercier ◽  
A. J. Souza
Keyword(s):  
Wind Stress ◽  
Ocean Circulation ◽  
Stress Component ◽  
Surface Wind ◽  
Coastal Ocean ◽  
Surface Mixed Layer ◽  
Residual Circulation ◽  
Surface Wind Stress ◽  
The Uk ◽  
Charnock Relation

Abstract. The accurate parameterisation of momentum and heat transfer across the air-sea interface is vital for realistic simulation of the atmosphere-ocean system. In many modelling applications accurate representation of the wind stress is required to numerically reproduce surge, coastal ocean circulation, surface waves, turbulence and mixing. Different formulations can be implemented and impact the accuracy of: the instantaneous and long-term residual circulation; the surface mixed layer; and the generation of wave-surge conditions. This, in turn, affects predictions of storm impact, sediment pathways, and coastal resilience to climate change. The specific numerical formulation needs careful selection to ensure the accuracy of the simulation. Two wind stress formulae widely used in respectively the ocean circulation and the storm surge communities are studied with focus on an application to the NW region of the UK. Model-observation validation is performed at two nearshore and one estuarine ADCP stations in Liverpool Bay, a hypertidal region of freshwater influence with vast intertidal areas. The period of study covers both calm and extreme conditions to fully test the robustness of the 10 m wind stress component of the Common Ocean Reference Experiment (CORE) bulk formulae and the Charnock relation. In this coastal application a realistic barotropic-baroclinic simulation of the circulation and surge elevation is setup, demonstrating greater accuracy occurs when using the Charnock relation for surface wind stress.

The impact of topography and eddy parameterization on the simulated Southern Ocean circulation response to changes in surface wind stress

2020 ◽  
Author(s):  
Hailu Kong ◽  
Malte F. Jansen
Keyword(s):  
Southern Ocean ◽  
Wind Stress ◽  
Ocean Circulation ◽  
Surface Wind ◽  
Flat Bottom ◽  
Coarse Resolution ◽  
Surface Wind Stress ◽  
Stress Changes ◽  
The Impact ◽  
Meso Scale

AbstractIt remains uncertain how the Southern Ocean circulation responds to changes in surface wind stress, and whether coarse resolution simulations, where meso-scale eddy fluxes are parameterized, can adequately capture the response. We address this problem using two idealized model setups mimicking the Southern Ocean: a flat bottom channel, and a channel with moderately complex topography. Under each topographic configuration and varying wind stress, we compare several coarse resolution simulations, configured with different eddy parameterizations, against an eddy-resolving simulation. We find that: (1) without topography, sensitivity of the Antarctic Circumpolar Current (ACC) to wind stress is overestimated by coarse resolution simulations, due to an underestimate of the sensitivity of the eddy diffusivity; (2) in the presence of topography, stationary eddies dominate over transient eddies in counteracting the direct response of the ACC and overturning circulation to wind stress changes; (3) coarse resolution simulations with parameterized eddies capture this counteracting effect reasonably well, largely due to their ability to resolve stationary eddies. Our results highlight the importance of topography in modulating the response of the Southern Ocean circulation to changes in surface wind stress. The interaction between meso-scale eddies and stationary meanders induced by topography requires more attention in future development and testing of eddy parameterizations.

scholarly journals Test and evaluation of a simple parameterization to enhance air-sea coupling in a global coupled model

2018 ◽  
Vol 3 (3) ◽  
Author(s):  
Fanghua Xu 1
Keyword(s):  
Wind Stress ◽  
Ocean Circulation ◽  
Southern Oscillation ◽  
Current System ◽  
Surface Wind ◽  
Coupled Model ◽  
Global Ocean ◽  
Western Boundary ◽  
Surface Wind Stress ◽  
Gyre Circulation

A simple temperature-dependent wind stress scheme is implemented in National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM), aiming to enhance positive wind stress and sea surface temperature (SST) correlation in SST-frontal regions. A series of three-year coupled experiments are conducted to determine a proper coupling coefficient for the scheme based on the agreement of surface wind stress and SST at oceanic mesoscale between model simulations and observations. Afterwards, 80-year simulations with/without the scheme are conducted to explore its effects on simulated ocean states and variability. The results show that the new scheme indeed improves the positive correlation between SST and wind stress magnitude near the large oceanic fronts. With more realistic surface heat flux and wind stress, the global SST biases are reduced. The global ocean circulation represented by barotropic stream function exhibits a weakened gyre circulation close to the western boundary separation, in agreement with previous studies. The simulation of equatorial Pacific current system is improved as well. The overestimated El Niño Southern Oscillation (ENSO) magnitude in original CESM is reduced by ~30% after using the new scheme with an improved period.

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>

On the theory of the wind-driven ocean circulation

1962 ◽  
Vol 12 (1) ◽  
pp. 49-80 ◽  
Author(s):  
G. F. Carrier ◽  
A. R. Robinson
Keyword(s):  
Wind Stress ◽  
Ocean Circulation ◽  
Surface Wind ◽  
Inviscid Flow ◽  
Relative Vorticity ◽  
Wind Stress Curl ◽  
Meridional Transport ◽  
Surface Distribution ◽  
Surface Wind Stress ◽  
Mean Circulation

A surface distribution of stress is imposed on an ocean enclosed by two continental boundaries; the resulting transport circulation is studied between two latitudes of zero surface wind-stress curl, within which the curl reaches a single maximum. Under the assumption that turbulent transfer of relative vorticity has a minimum effect on the mean circulation, inviscid flow patterns are deduced in the limit of small transport Rossby number. Inertial currents, or naturally scaled regions of high relative vorticity, occur on both the eastern and the western continental coasts. Limits on the relative transports of the currents are obtained and found to depend on the direction of variation of the wind-stress curl with latitude, relative to that of the Coriolis accelerations. The most striking feature of the inviscid flow is a narrow inertial current the axis of which lies along the latitude of maximum wind-stress curl. All eastward flow occurs in this midlatitude jet.A feature of the flow which cannot remain essentially free of turbulent processes is the integrated vorticity relationship, since the imposed wind-stress distribution acts as a net source of vorticity for the ocean. Heuristic arguments are used together with this integral constraint to deduce the presence and strength of the turbulent diffusion which must occur in the region of the mid-latitude jet. It is further inferred that the turbulent meanders of the jet must effect a net meridional transport of relative vorticity.

FEATURES OF WIND FIELD OVER THE SEA SURFACE IN THE COASTAL AREA BASED ON SAR OBSERVATIONS

2017 ◽  
Author(s):  
Anna Monzikova ◽  
Anna Monzikova ◽  
Vladimir Kudryavtsev Vladimir ◽  
Vladimir Kudryavtsev Vladimir ◽  
Alexander Myasoedov ◽  
...  
Keyword(s):  
Wind Stress ◽  
Surface Wind ◽  
Quantitative Description ◽  
Energy Resource ◽  
Resource Assessment ◽  
Internal Boundary Layer ◽  
Offshore Wind ◽  
Internal Boundary ◽  
Sar Images ◽  
Surface Wind Stress

“Wind-shadowing” effects in the Gulf of Finland coastal zone are analyzed using high resolution Envisat Synthetic Aperture Radar (SAR) measurements and model simulations. These effects are related to the internal boundary layer (IBL) development due to abrupt change the surface roughness at the sea-land boundary. Inside the "shadow" areas the airflow accelerates and the surface wind stress increases with the fetch. Such features can be revealed in SAR images as dark areas adjacent to the coastal line. Quantitative description of these effects is important for offshore wind energy resource assessment. It is found that the surface wind stress scaled by its equilibrium value (far from the coast) is universal functions of the dimensionless fetch Xf/G. Wind stress reaches an equilibrium value at the distance Xf/G of about 0.4.

Wind Stress Over Waves: Effects of Sea Roughness and Atmospheric Stability

2002 ◽  
Vol 124 (3) ◽  
pp. 169-172 ◽  
Author(s):  
Dag Myrhaug ◽  
Olav H. Slaattelid
Keyword(s):  
Boundary Layer ◽  
Wind Stress ◽  
Local Equilibrium ◽  
Surface Wind ◽  
Atmospheric Stability ◽  
Sea Surface ◽  
Stability Function ◽  
Sea Surface Wind ◽  
Surface Wind Stress ◽  
Sea Surface Roughness

The paper considers the effects of sea roughness and atmospheric stability on the sea surface wind stress over waves, which are in local equilibrium with the wind, by using the logarithmic boundary layer profile including a stability function, as well as adopting some commonly used sea surface roughness formulations. The engineering relevance of the results is also discussed.

Uncertainties in reanalysis surface wind stress and their relationship with observing systems

2018 ◽  
Vol 52 (5-6) ◽  
pp. 3061-3078 ◽  
Author(s):  
Caihong Wen ◽  
Arun Kumar ◽  
Yan Xue
Keyword(s):  
Wind Stress ◽  
Surface Wind ◽  
Surface Wind Stress ◽  
Observing Systems

scholarly journals Southern Ocean Wind Stress in CMIP5 Models: Role of Wind Fluctuations

2020 ◽  
Vol 33 (4) ◽  
pp. 1209-1226 ◽  
Author(s):  
Xia Lin ◽  
Xiaoming Zhai ◽  
Zhaomin Wang ◽  
David R. Munday
Keyword(s):  
Southern Ocean ◽  
Time Scales ◽  
Wind Stress ◽  
Surface Wind ◽  
Coupled Model ◽  
Cmip5 Models ◽  
Coupled Models ◽  
Surface Wind Stress ◽  
Stress Changes ◽  
The Mean

AbstractThe Southern Ocean (SO) surface wind stress is a major atmospheric forcing for driving the Antarctic Circumpolar Current and the global overturning circulation. Here the effects of wind fluctuations at different time scales on SO wind stress in 18 models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) are investigated. It is found that including wind fluctuations, especially on time scales associated with synoptic storms, in the stress calculation strongly enhances the mean strength, modulates the seasonal cycle, and significantly amplifies the trends of SO wind stress. In 11 out of the 18 CMIP5 models, the SO wind stress has strengthened significantly over the period of 1960–2005. Among them, the strengthening trend of SO wind stress in one CMIP5 model is due to the increase in the intensity of wind fluctuations, while in all the other 10 models the strengthening trend is due to the increasing strength of the mean westerly wind. These discrepancies in SO wind stress trend in CMIP5 models may explain some of the diverging behaviors in the model-simulated SO circulation. Our results suggest that to reduce the uncertainty in SO responses to wind stress changes in the coupled models, both the mean wind and wind fluctuations need to be better simulated.

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