Observation and modeling of surface currents on the Grand Banks: A study of the wave effects on surface currents

Tang, Choon Yik; Perrie, Will; Jenkins, Alastair D.; DeTracey, Brendan; Hu, Yan; Toulany, Bechara; Smith, Peter C.

doi:10.1029/2006jc004028

Cited by 44 publications

(53 citation statements)

References 58 publications

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“…The significance of the former and latter component in the surface currents over the Grand Banks was clearly demonstrated by Han (2005) and Tang et al (2007), respectively. In this algorithm, the eddy viscosity ν is assumed to be proportional to the surface friction velocity u * and a characteristic depth H:…”

Section: Blending Of the Satellite-and Model-derived Mean Currentsmentioning

confidence: 98%

“…2c. Table 5 shows that the composite and observed currents at the surface are much closer than at 15 m depth, (2003) and Tang et al (2007) found using numerical ocean models, inclusion of the Stokes drift is necessary to represent the surface current speed in this region accurately.…”

Section: Comparison With Surface Driftersmentioning

confidence: 99%

“…In this section, we compare composite currents to surface drifters that were deployed over the Grand Banks in the fall of 2002 (Tang et al, 2007). Hourly data of surface currents derived from drifter positions (C. L. Tang, personal communication, 2012) were re-sampled every six hours and compared with composite currents that were calculated using six-hourly winds at the surface and the temporal mean currents shown in Fig.…”

Section: Comparison With Surface Driftersmentioning

confidence: 99%

“…Fratantoni and Pickart (2007) used historical hydrographic data to describe the spatial evolution of the summertime shelf-break front (and its associated current system) from Greenland to the Middle Atlantic Bight and identified the Tail (southern end) of the Grand Banks as an important location in this spatial evolution. Numerical studies of the circulation in this region have included simulation by finitedifference (e.g., Tang et al, 2007) and finite-element (e.g., Han & Loder, 2003;Han et al, 2008) models. Perrie, Tang, Hu, and DeTracy (2003) and Tang et al (2007) coupled wave models to ocean circulation models of the Newfoundland and Labrador Shelf, and found the effects of surface waves on surface currents and drifter trajectories to be significant.…”

Section: Introductionmentioning

confidence: 99%

“…Numerical studies of the circulation in this region have included simulation by finitedifference (e.g., Tang et al, 2007) and finite-element (e.g., Han & Loder, 2003;Han et al, 2008) models. Perrie, Tang, Hu, and DeTracy (2003) and Tang et al (2007) coupled wave models to ocean circulation models of the Newfoundland and Labrador Shelf, and found the effects of surface waves on surface currents and drifter trajectories to be significant. The advantage of such models, compared to a method such as ours, is that the models can account for the different processes involved in the interaction between winds, waves and currents (input of wind energy to waves, energy transfer between waves, and the distribution of dissipated energy among currents, wave breaking, etc.).…”

Section: Introductionmentioning

confidence: 99%

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Northwest Atlantic Surface Circulation from Multi-Satellite Observations

2012

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The advent of satellite remote sensing has led to new ways of monitoring and studying the nearsurface ocean circulation, but its use has often been limited to the deep ocean. Here we present and validate a method of reconstructing the near-surface currents from multi-sensor satellite data off Atlantic Canada with a resolution of 0.25°, for the period from October 1992 to September 2006. The reconstructed ocean circulation consists of a superposition of 1) depth-variable wind-induced Ekman currents and surface wave-induced Stokes drift calculated from scatterometer-measured wind velocities using a theoretical formulation; 2) depth-invariant geostrophic surface current anomalies calculated from altimetric sea surface height anomalies; and 3) mean currents that are a combination of model-simulated currents for the Newfoundland and southern Labrador Shelves and satelliteobserved currents for the rest of the study region. The method features two novel aspects: the integration of simulated and satellite-observed mean circulation fields, and the consideration of the surface wave-induced Stokes drift. Individual weekly-mean composite current fields show considerable temporal variation and spatial structure. Inclusion of the numerically simulated mean circulation field leads to better agreement between the composite currents and buoy-observed currents at 15 m depth, compared to using the satellite-derived mean current field alone. There is also fair agreement between the composite currents and instantaneous currents observed at various depths by shipboard acoustic Doppler current profiler (ADCP) data, with a correlation coefficient of 0.59 (a 95% confidence interval of 0.49-0.68) and a vector difference ratio of 0.61. The 15 m depth composite currents agree better with buoy-observed currents than a similar near-surface current product with coarser horizontal resolution. At the sea surface, composite currents calculated with Stokes drift have a mean speed of 0.35 m s −1 , similar to currents observed by drifters (0.36 m s −1 ), but exclusion of the Stokes drift leads to an underestimation of the current speed. The present study demonstrates that an appropriate integration of multi-sensor satellite data can provide approximate near-surface current information and could be used for routine monitoring of the shelf circulation at synoptic scales, complementing in situ observations and numerical ocean modelling.RÉSUMÉ [Traduit par la rédaction] La télédétection par satellite a fourni de nouveaux moyens de surveiller et d'étudier la circulation océanique près de la surface, mais son emploi a souvent été limité à l'océan profond. Ici, nous présentons et validons une méthode de reconstruction des courants près de la surface à partir des données de satellites multicapteurs au large du Canada atlantique avec une résolution 0.25°pour la période allant d'octobre 1992 à septembre 2006. La circulation océanique reconstruite consiste en une superposition 1) de courants d'Ekman de profondeur variable produits par le vent et de d...

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Section: Blending Of the Satellite-and Model-derived Mean Currentsmentioning

confidence: 98%

Section: Comparison With Surface Driftersmentioning

confidence: 99%

Section: Comparison With Surface Driftersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Northwest Atlantic Surface Circulation from Multi-Satellite Observations

2012

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A modeling study of the impact of major storms on waves, surface and near‐bed currents on the Grand Banks of Newfoundland

Prescott²,

Tang

2015

JGR Oceans

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Waves and current processes, both surface and near‐bed were simulated for major storms on the Grand Banks of Newfoundland using integrated wave, 3‐D tidal and ocean current models. Most storms track southwest to northeast and pass to the north or northwest of the Grand Banks. Significant wave heights can reach up to ∼14 m and are predominantly to the northeast at the peak of storms. Extreme surface currents reach approximately 1 m s−1 and are largely to the southeast. The strongest bottom currents, up to 0.8 m s−1, occur on St. Pierre Bank and are dominantly to the south and southeast. While wave height and wind‐driven current generally increase with wind speed, factors such as storm paths, the relative location of the storm center at the storm peak, and storm translation speed also affect waves and currents. Surface and near‐bed wind‐driven currents both rotate clockwise and decrease in strength as the storm traverses the Grand Banks. While the spatial variability of the storm impact on surface currents is relatively small, bottom currents show significant spatial variation of magnitude and direction as well as timing of peak current conditions. These spatial variations are controlled by the changes of bathymetry and mixed layer depth over the model domain. The storm‐generated currents can be 7 to 10 times stronger than the background mean currents. These strong currents interact with wave oscillatory flows to produce shear velocities up to 15 cm s−1 and cause wide occurrences of strong sediment transport over nearly the entire Grand Banks.

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The impact of wave‐induced Coriolis‐Stokes forcing on satellite‐derived ocean surface currents

Hui

2016

JGR Oceans

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Ocean surface currents estimated from the satellite data consist of two terms: Ekman currents from the wind stress and geostrophic currents from the sea surface height (SSH). But the classical Ekman model does not consider the wave effects. By taking the wave‐induced Coriolis‐Stokes forcing into account, the impact of waves (primarily the Stokes drift) on ocean surface currents is investigated and the wave‐modified currents are formed. The products are validated by comparing with OSCAR currents and Lagrangian drifter velocity. The result shows that our products with the Stokes drift are better adapted to the in situ Lagrangian drifter currents. Especially in the Southern Ocean region (40°S–65°S), 90% (91%) of the zonal (meridional) currents have been improved compared with currents that do not include Stokes drift. The correlation (RMSE) in the Southern Ocean has also increased (decreased) from 0.78 (13) to 0.81 (10.99) for the zonal component and 0.76 (10.87) to 0.79 (10.09) for the meridional component. This finding provides the evidence that waves indeed play an important role in the ocean circulation, and need to be represented in numerical simulations of the global ocean circulation.

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Observation and modeling of surface currents on the Grand Banks: A study of the wave effects on surface currents

Cited by 44 publications

References 58 publications

Northwest Atlantic Surface Circulation from Multi-Satellite Observations

Northwest Atlantic Surface Circulation from Multi-Satellite Observations

A modeling study of the impact of major storms on waves, surface and near‐bed currents on the Grand Banks of Newfoundland

The impact of wave‐induced Coriolis‐Stokes forcing on satellite‐derived ocean surface currents

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