Surface Imprints of Water-Column Turbulence: A Case Study of Tidal Flow over an Estuarine Sill

Marmorino, G. O.; Smith, Geoffrey B.; Miller, W. David

doi:10.3390/rs5073239

Cited by 7 publications

(6 citation statements)

References 31 publications

(47 reference statements)

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“…(a) Observed sea surface temperature of a cyclonic eddy in the Southern California Countercurrent. The image was taken on 1 February 2013 at 20:34 in the framework of SubEx (Marmorino et al, 2018). (b) Modelled salinity and (c) potential temperature of the cyclone C3 on 26 June at 15 m of depth (see Figs.…”

Section: Discussionmentioning

confidence: 99%

Very high-resolution modelling of submesoscale turbulent patterns and processes in the Baltic Sea

2020

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Abstract. In order to simulate submesoscale turbulent patterns and processes (STPPs) and to analyse their properties and dynamics, the Regional Ocean Modeling System (ROMS) was run for June 2016 in a subregion of the Baltic Sea. To create a realistic mesoscale environment, ROMS with 500 m horizontal resolution (referred to as R500) is one-way nested into an existing operational model, and STPPs with horizontal scales < 1 km are resolved with a second nest of 100 m resolution (R100). Both nests use 10 terrain-following layers in the vertical. The comparison of the R500 results with a satellite image shows fair agreement. While R500 is driven by realistic air–sea fluxes, the atmospheric forcing is turned off in R100 because it prevents the generation of STPPs and blurs submesoscale structures. Therefore, R100 provides deep insight into ageostrophic processes and associated quantities under quasi-adiabatic conditions that are approximately met in no-wind or light-wind situations. The validity of the results is furthermore limited to the selected region and the time of the year. STPPs evolve rapidly within a about a day. They are characterized by vertical speeds of 𝒪(10) m d−1 and relative vorticities and divergences reaching multiples of the Coriolis parameter. Typical elements of the secondary circulation of two-dimensional strain-induced frontogenesis are identified at an exemplary front in shallow water, and details of the ageostrophic flow field are revealed. The conditions for inertial and symmetric instability are evaluated for the whole domain, and the components of the tendency equation are computed in a subregion. While anticyclonic eddies are generated solely along coasts, cyclonic eddies are rolled-up streamers and found in the entire domain. A special feature of the cyclones is their ability to absorb internal waves and to sustain patches of continuous upwelling for several days, favouring plankton growth. The kinematic properties show good agreement with observations, while some observed details within a small cyclonic eddy are only partly reproduced, most likely due to a lack of horizontal resolution or nonhydrostatic effects.

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Section: Discussionmentioning

confidence: 99%

Very high-resolution modelling of submesoscale turbulent patterns and processes in the Baltic Sea

2020

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“…A growing number of airborne studies [10][11][12][13][14][15][16] demonstrated the power of this remote sensing modality to detect and image a wide variety of dynamical processes taking place at or below the air-sea interface. A mid-or long-wave infrared camera is capturing passive radiation emitted by the water no deeper than the skin layer, i.e., tens of microns.…”

Section: Infrared Methodsmentioning

confidence: 99%

Airborne Remote Sensing of the Upper Ocean Turbulence during CASPER-East

et al. 2018

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This study takes on the challenge of resolving upper ocean surface currents with a suite of airborne remote sensing methodologies, simultaneously imaging the ocean surface in visible, infrared, and microwave bands. A series of flights were conducted over an air-sea interaction supersite established 63 km offshore by a large multi-platform CASPER-East experiment. The supersite was equipped with a range of in situ instruments resolving air-sea interface and underwater properties, of which a bottom-mounted acoustic Doppler current profiler was used extensively in this paper for the purposes of airborne current retrieval validation and interpretation. A series of water-tracing dye releases took place in coordination with aircraft overpasses, enabling dye plume velocimetry over 100 m to 10 km spatial scales. Similar scales were resolved by a Multichannel Synthetic Aperture Radar, which resolved a swath of instantaneous surface velocities (wave and current) with 10 m resolution and 5 cm/s accuracy. Details of the skin temperature variability imprinted by the upper ocean turbulence were revealed in 1-14,000 m range of spatial scales by a mid-wave infrared camera. Combined, these methodologies provide a unique insight into the complex spatial structure of the upper ocean turbulence on a previously under-resolved range of spatial scales from meters to kilometers. However, much attention in this paper is dedicated to quantifying and understanding uncertainties and ambiguities associated with these remote sensing methodologies, especially regarding the smallest resolvable turbulent scales and reference depths of retrieved currents.Keywords: airborne remote sensing; ocean surface currents; upper ocean turbulence BackgroundCapabilities for spatial measurements of ocean surface turbulence are highly desirable for a wide variety of needs ranging from basic studies of upper ocean mixing processes to data assimilation into high-resolution coastal and ocean circulation models. On the global scale, presently available observations of the ocean currents are provided by satellite altimeters, which are limited to mesoscales and resolve only the geostrophic component of the surface current. Much anticipated launches of the

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“…16) near its tail with diameters of about 10 m and mean distances of 20 m. From a video, it appears that the spots are accompanied by breaking surface waves. Potentially, the spots are created by intense turbulent mixing (Marmorino et al, 2013). Because of the small scales it is certainly not possible to model the spots with R100, but it is weird that the model on the one hand reproduces filaments with width of 2 times the model resolution (200 m), and contrariwise, the smallest eddy sizes in R100 are around 1 km, i.e.…”

Section: Comparison Of Features With Observationsmentioning

confidence: 99%

Very high-resolution modelling of submesoscale turbulent patterns and processes in the Baltic Sea

Onken¹,

Baschek²,

Angel-Benavides³

2019

Preprint

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Abstract. In order to simulate submesoscale turbulent patterns and processes (STPPs) and to analyse their properties and dynamics, the Regional Ocean Modeling System (ROMS) is applied to a subregion of the Baltic Sea around the island of Bornholm. The modeled STPPs provide an aid for the interpretation of observations that were taken during the Expedition Clockwork Ocean in the same region in June 2016. To create a realistic mesoscale and submesoscale environment, ROMS with 500-m horizontal resolution is one-way nested into an existing operational model. The comparison of the results with satellite images shows good agreement. STPPs with horizontal scales

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Surface Imprints of Water-Column Turbulence: A Case Study of Tidal Flow over an Estuarine Sill

Cited by 7 publications

References 31 publications

Very high-resolution modelling of submesoscale turbulent patterns and processes in the Baltic Sea

Very high-resolution modelling of submesoscale turbulent patterns and processes in the Baltic Sea

Airborne Remote Sensing of the Upper Ocean Turbulence during CASPER-East

Very high-resolution modelling of submesoscale turbulent patterns and processes in the Baltic Sea

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