Measurements of Near-Surface Turbulence and Mixing from Autonomous Ocean Gliders

Laurent, Louis C. St.; Merrifield, Sophia

doi:10.5670/oceanog.2017.231

Cited by 32 publications

(11 citation statements)

References 29 publications

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“…In particular, the sharpness of the density gradient changes the surface/interior kinetic energy ratio cutoff rate, which scales like c 4 ∝ κ −4 for an infinitely sharp step and c 2 ∝ κ −2 for a finite‐width density gap, as well as the width and magnitude of the amplification peak. Sharp and stable mixed layers have been observed over limited periods in some regions of the ocean (e.g., St. Laurent & Merrifield, ), like during the formation of diurnal warm layer in the upper few meters, which has already been investigated in the context of internal wave dynamics (Bogdanoff, , chapter 3). We also evidenced the potential impact of horizontal (sub)mesoscale inhomogeneities in the stratification near the surface on the internal wave activity, especially in winter.…”

Section: Resultsmentioning

confidence: 99%

“…This associated amplification in summer was qualitatively reproduced by Rocha et al (; supporting information), using stratification profiles from the World Ocean Atlas database (WOA13). With the exception of Rocha et al (), not much effort has been dedicated to the validation of the idealized model of D'Asaro () against actual observations or high‐resolution modeling, while the mechanism described is regularly invoked (Callies & Ferrari, ; St. Laurent & Merrifield, ; Qiu et al, ; Torres et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Sea Surface Signature of Internal Tides

Lahaye

Gula

Roullet

2019

Geophysical Research Letters

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The upper ocean is energetic at scales below the Rossby deformation radius owing to the existence of internal waves and submesoscale fronts and vortices. These contribute significantly to energy dissipation, tracer mixing, and exchanges between the ocean surface layer, the ocean interior, and the atmospheric boundary layer. Internal waves and submesoscale motions both undergo strong spatial and seasonal variations, driven by different mechanisms. Here, we investigate the sea surface signature of internal waves and its seasonality using linear wave theory and a high‐resolution realistic simulation. In summer, internal waves are greatly amplified near the surface mostly due to a thin mixed layer bounded by a seasonal pycnocline. This surface amplification is well captured by linear theory, provided that the stratification at the base of the mixed layer is accurately represented. In winter, the superinertial motions are not fully explained by linear theory, reflecting impacts of the more energetic submesoscale motions.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sea Surface Signature of Internal Tides

Lahaye

Gula

Roullet

2019

Geophysical Research Letters

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“…This indicates the importance of diapycnal heat flux at the base of the ML to determine the seasonal evolution of ML heat budget in the AS. Microstructure temperature measurements through mooring (Moum et al, ; Warner et al, ) or autonomous profiling float (St. Laurent & Merrifield, ) may provide useful information on the seasonal variability of diapycnal heat flux at the base of ML in the AS.…”

Section: Discussionmentioning

confidence: 99%

“…autonomous profiling float (St. Laurent & Merrifield, 2017) may provide useful information on the seasonal variability of diapycnal heat flux at the base of ML in the AS. The encouragement provided by the Director, INCOIS, is gratefully acknowledged.…”

Section: Journal Of Geophysical Research: Oceansmentioning

confidence: 99%

Observed Upper Ocean Seasonal and Intraseasonal Variability in the Andaman Sea

et al. 2019

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The observed seasonal and intraseasonal evolution of near‐surface meteorological and oceanographic variables in the Andaman Sea for the period March 2014 to December 2017 are examined using moored buoy observations at 10.5°N, 94°E. The amplitude of temperature inversions is very weak (0.2 to 0.4 °C), and they appeared primarily during winter (November–January) and latter part of summer (May–August). The net surface heat flux plays a primary role, and vertical processes term contributes secondarily to determine the seasonal mixed layer (ML) heat storage variability. Consistent with the seasonal variations of formation and strength of temperature inversion, vertical processes term shows a positive tendency during winter. The sea surface salinity shows large amplitude intraseasonal variability during fall and winter, and it is attributed to the variability of horizontal circulation in the presence of large lateral sea surface salinity gradients at the mooring location. The sea surface temperature shows the presence of strong intraseasonal variability between 20 and 80 days, though its amplitude of oscillation is distinctly higher during May–October than November–April. Band‐pass filtered (20–80 days) time series of different components of the ML heat budget shows that the net surface heat flux primarily determines the intraseasonal ML heat storage variability. Our analysis further shows that during May–October, both net shortwave radiation and latent heat flux together determine the modulation of the intraseasonal net surface heat flux. In contrast, latent heat flux acts as the sole factor to determine the modulation of the intraseasonal net surface heat flux during November–April.

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“…Observations from the T-gliders indicated the surprising role of the upperocean diurnal cycle in enhancing turbulence levels in the near-surface stable layer (Bogdanoff, 2017;St. Laurent and Merrifield, 2017, in this issue).…”

Section: Autonomous Self-propelledmentioning

confidence: 99%