Enhanced Turbulence Associated with the Diurnal Jet in the Ocean Surface Boundary Layer

Sutherland, Graig; Marié, Louis; Reverdin, Gilles; Christensen, Kai Håkon; Broström, Göran; Ward, Brian

doi:10.1175/jpo-d-15-0172.1

Cited by 42 publications

(86 citation statements)

References 56 publications

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“…However, turbulence estimates associated with the diurnal warm layer shear, such as Wang (2001), are much smaller than observed during the SPURS-I field campaign. The results of this study are not inconsistent with a recent study in the same region as SPURS-I just a few weeks before the first cruise (Sutherland et al, 2016). Using the ASIP, Sutherland et al (2016) show enhanced TKE dissipation in the upper ocean and relate it to shear across the DWL, using boundary layer scaling.…”

Section: Introductionsupporting

confidence: 50%

“…The results of this study are not inconsistent with a recent study in the same region as SPURS-I just a few weeks before the first cruise (Sutherland et al, 2016). Using the ASIP, Sutherland et al (2016) show enhanced TKE dissipation in the upper ocean and relate it to shear across the DWL, using boundary layer scaling. However, their observations were under different wind speed conditions and here it will be demonstrated that the shear of the diurnal warm layer alone cannot explain all of the observed enhanced TKE dissipation.…”

Section: Introductionsupporting

confidence: 50%

“…Similar to ASIP, the greatest benefit of the glider platform, used in this study, is the ability to take microstructure measurements through the surface during the ascent of the glider and the seclusion of the glider from potential anthropogenic turbulence generators, such as the ship. Sutherland et al (2016) made microstructure measurements, including TKE dissipation, during a French research cruise associated with the SPURS-I field campaign in late August and early September 2012. Using the ASIP, described above, and a custom buoy to measure near-surface currents, they observed an intensified near-surface currents and enhanced TKE dissipation associated with DWLs across six diurnal cycles.…”

Section: Past Work and Present State Of Knowledgementioning

confidence: 99%

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Physics of diurnal warm layers : turbulence, internal waves, and lateral mixing

Bogdanoff¹

2017

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Section: Introductionsupporting

confidence: 50%

Section: Introductionsupporting

confidence: 50%

Section: Past Work and Present State Of Knowledgementioning

confidence: 99%

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Physics of diurnal warm layers : turbulence, internal waves, and lateral mixing

Bogdanoff¹

2017

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“…This makes the layer respond more rapidly to atmospheric forcing. Bao et al () showed an increase of surface currents of up to 0.4 m/s in a modeled freshwater lens, an effect analogous to the surface jet formation observed within strongly stratified layers caused by diurnal warming (Brainerd & Gregg, ; Callaghan et al, ; Sutherland et al, ). Such an acceleration of horizontal currents was also observed by Wijesekera et al () to occur within a large freshwater lens in the eastern tropical Pacific.…”

Section: Introductionmentioning

confidence: 86%

Upper Ocean Response to Rain Observed From a Vertical Profiler

et al. 2019

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Rainfall induces a vertical salinity gradient directly below the ocean surface, the strength and lifetime of which depend on the size of the rain event, the availability of mixing, and the air‐sea heat fluxes. The presence of rain in turn influences the near‐surface turbulent mixing and air‐sea exchange processes. During a campaign in the midlatitude North Atlantic, the Air‐Sea Interaction Profiler (ASIP) was used to investigate changes in the vertical distribution of salinity (S), temperature (T), and turbulent kinetic energy dissipation rate (ϵ) caused by four rain events. During one of the rain events a strong shallow stratification was formed. The buoyancy effect of this freshwater lens changes the dominant wind‐driven turbulent mixing. The surface momentum flux was limited to a shallow layer, and below it ϵ is reduced by 2 orders of magnitude. For a different rain event of higher‐peak rain rate, the salinity anomaly is smaller and is dispersed deeper into the water column. The difference in ocean response shows that the upper ocean is sensitive to changes in the atmospheric forcing associated with the rain events. The observed salinity anomalies as a function of rain rate and wind speed are compared to relationships from studies with the 1‐D turbulence model GOTM and satellite validation. The observations suggest that the vertical salinity anomaly is best described as a function of total rain. A higher‐resolution prognostic model for sea surface salinity and temperature is shown to perform well in predicting the observed S and T anomalies.

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“…The origin of the diurnal cycle in diffusivity is not entirely clear and is a topic of further exploration. A few noteworthy points, (1) the diurnal signal in diffusivity is narrowband (Figure S3), (2) the internal tide signal (as diagnosed with band‐passed, depth‐dependent velocity; not shown) has a stronger semidiurnal component (energy density ∼10 J/m 3 ) than diurnal (energy density <5 J/m 3 ), and (3) a strong diurnal signal in temperature stratification is not seen during this time period (Figure S3; e.g., as would be anticipated for the development of a diurnal jet; Sutherland et al, ). A weak narrowband diurnal signal is apparent in the east‐west wind stress (Figure S4) during this time, so a possible interpretation is that the signal is in response to acceleration of the water column by the winds.…”

Section: Observed Upper‐ocean Turbulencementioning

confidence: 95%

Seasonality and Buoyancy Suppression of Turbulence in the Bay of Bengal

Thakur

Govindarajan

Farrar

et al. 2019

Geophysical Research Letters

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A yearlong record from moored current, temperature, conductivity, and four mixing meters (χpods) in the northernmost international waters of the Bay of Bengal quantifies upper‐ocean turbulent diffusivity of heat (Kt) and its response to the Indian monsoon. Data indicate (1) pronounced intermittency in turbulence at semidiurnal, diurnal, and near‐inertial timescales, (2) strong turbulence above 25‐m depth during the SW (summer) and NE (winter) monsoon relative to the transition periods (compare Kt > 10−4 m2/s to Kt ∼ 10−5 m2/s, and (3) persistent suppression of turbulence (Kt < 10−5 m2/s) for 3 to 5 months in the latter half of the SW monsoon coincident with enhanced near‐surface stratification postarrival of low‐salinity water from the Brahmaputra‐Ganga‐Meghna delta and monsoonal precipitation. This suppression promotes maintenance of the low‐salinity surface waters within the interior of the bay preconditioning the upper northern Indian Ocean for the next year's monsoon.

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Enhanced Turbulence Associated with the Diurnal Jet in the Ocean Surface Boundary Layer

Abstract: International audienc

Cited by 42 publications

References 56 publications

Physics of diurnal warm layers : turbulence, internal waves, and lateral mixing

Physics of diurnal warm layers : turbulence, internal waves, and lateral mixing

Upper Ocean Response to Rain Observed From a Vertical Profiler

Seasonality and Buoyancy Suppression of Turbulence in the Bay of Bengal

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