The LatMix Summer Campaign: Submesoscale Stirring in the Upper Ocean (original) (raw)
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Collaborative Proposal: Studies of Stirring and Mixing at the Submesoscale in the Ocean
2010
The long term goal of the "Scalable Lateral Mixing and Coherent Turbulence" DRI, under which the PIs are funded, is to understand the processes that stir and mix tracers in the ocean on lateral scales of 100 kilometers to 10 meters, the so-called submesoscales. The specific long term goals of the PIs are to understand the influence of mesoscale strain in driving stirring and mixing at the submesoscale, and to develop a robust theoretical framework through which to interpret the observations.
Marine Turbulence: Theories, Observations, and Models
2005
Marine Turbulence: Theories, Observations, and Models is the first book to give a comprehensive overview of measurement techniques and theories for marine turbulence and mixing processes. It describes the processes which control the mixing of greenhouse gases, nutrients, trace elements, and hazardous substances in our oceans and shelf seas-from local to planetary scales. These processes buffer climate changes and are centrally important for regional to global ecosystem dynamics. The book is divided into eight parts. Part I introduces the nature of turbulence in relation to stratification, waves, and intermittence. Part II describes observational techniques for field studies. Part III presents selected computational means for the study of turbulence. Part IV introduces details of boundary layers. Parts V and VI present practical case studies in estuaries, fjords, lakes, and shelf seas, and at the shelf edge. Part VII bridges the smallscale three-dimensional turbulence and quasi-two-dimensional turbulence occurring on the planetary scale. Part VIII concludes the book with an overview of comprehensive data sets and models codes. The enclosed CD-ROM contains source codes of turbulence models and models of the upper-ocean mixing layer (COHERENS and GOTM), and observational data sets of turbulence characteristics or corresponding proxies of waters from all over the world. Marine Turbulence, written by a team of 53 world-leading experts as part of the Comparative Analysis and Rationalization of Second-Moment Turbulence Models (CARTUM) group, provides a rich source of data and methods for students and professionals working on environmental and climate problems. Specifically, it will be valuable for students and scientists in oceanography, hydrology, limnology, and meteorology, as well as marine, naval, and civil engineers.
Quantify Lateral Dispersion and Turbulent Mixing by Spatial Array of Chi-EM-APEX Floats
LONG-TERM GOALS Our long-term scientific goals are to understand the dynamics and identify mechanisms of small-scale processes––i.e., internal tides, inertial waves, nonlinear internal waves, vortical modes, and turbulence mixing––in the ocean and thereby help develop improved parameterizations of mixing for ocean models. Mixing within the stratified ocean is a particular focus as the complex interplay of internal waves from a variety of sources and turbulence makes this a current locus of uncertainty. Our focus is on observing processes that lead to lateral mixing of water properties. OBJECTIVES Our primary scientific objective is to improve our understanding and parameterization schemes of small-to submeso-scale oceanic processes. Dispersion due to lateral processes with vertical and horizontal shears could enhance turbulent mixing. Both internal waves and vortical motions exist at vertical scales smaller than order of 10 m and horizontal scales smaller than few km. They have dist...
Quarterly Journal of the Royal Meteorological Society, 2005
Marine Turbulence: Theories, Observations, and Models is the first book to give a comprehensive overview of measurement techniques and theories for marine turbulence and mixing processes. It describes the processes which control the mixing of greenhouse gases, nutrients, trace elements, and hazardous substances in our oceans and shelf seas-from local to planetary scales. These processes buffer climate changes and are centrally important for regional to global ecosystem dynamics. The book is divided into eight parts. Part I introduces the nature of turbulence in relation to stratification, waves, and intermittence. Part II describes observational techniques for field studies. Part III presents selected computational means for the study of turbulence. Part IV introduces details of boundary layers. Parts V and VI present practical case studies in estuaries, fjords, lakes, and shelf seas, and at the shelf edge. Part VII bridges the smallscale three-dimensional turbulence and quasi-two-dimensional turbulence occurring on the planetary scale. Part VIII concludes the book with an overview of comprehensive data sets and models codes. The enclosed CD-ROM contains source codes of turbulence models and models of the upper-ocean mixing layer (COHERENS and GOTM), and observational data sets of turbulence characteristics or corresponding proxies of waters from all over the world. Marine Turbulence, written by a team of 53 world-leading experts as part of the Comparative Analysis and Rationalization of Second-Moment Turbulence Models (CARTUM) group, provides a rich source of data and methods for students and professionals working on environmental and climate problems. Specifically, it will be valuable for students and scientists in oceanography, hydrology, limnology, and meteorology, as well as marine, naval, and civil engineers.
Theories" and techniques for observing turbulence in the ocean euphotic zone
With growing recognition of the important roles which turbulence plays in the functioning of marine food webs, interest in the tools and techniques of measuring turbulence in the ocean has spread from the physical to the biological oceanographic community, for which this paper is intended. The subject of ocean turbulence and its measurement is introduced, with emphasis on the euphotic zone of both deep ocean and coastal environments. A discussion of important characteristics of turbulence and the various means by which turbulence may affect components of the biological system is followed by a simplified outline of the mathematical means used to describe scales of variability produced by turbulent fields. Existing and developing techniques for field measurements of turbulence variables are described, with discussion of the "theories" which are often necessary to transform those variables which we can measure into those we actually wish to know.
Small-scale dispersion in the presence of Langmuir circulation
Journal of Physical Oceanography
We present an analysis of ocean surface dispersion characteristics, on 1-100 m scales, obtained by optically tracking a release of [Formula: see text] (600) bamboo plates for 2 hours in the Northern Gulf of Mexico. Under sustained 5-6 m/s winds, energetic Langmuir cells are clearly delineated in the spatially dense plate observations. Within 10 minutes of release, the plates collect in windrows with 15 m spacing aligned with the wind. Windrow spacing grows, through windrow merger, to 40 m after 20 minutes and then expands at a slower rate to 50 m. The presence of Langmuir cells produces strong horizontal anisotropy and scale dependence in all surface dispersion statistics computed from the plate observations. Relative dispersion in the crosswind direction initially dominates but eventually saturates, while downwind dispersion exhibits continual growth consistent with contributions from both turbulent fluctuations and organized mean shear. Longitudinal velocity differences in the cro...
Topographic enhancement of vertical turbulent mixing in the Southern Ocean
Nature Communications
It is an open question whether turbulent mixing across density surfaces is sufficiently large to play a dominant role in closing the deep branch of the ocean meridional overturning circulation. The diapycnal and isopycnal mixing experiment in the Southern Ocean found the turbulent diffusivity inferred from the vertical spreading of a tracer to be an order of magnitude larger than that inferred from the microstructure profiles at the mean tracer depth of 1,500 m in the Drake Passage. Using a high-resolution ocean model, it is shown that the fast vertical spreading of tracer occurs when it comes in contact with mixing hotspots over rough topography. The sparsity of such hotspots is made up for by enhanced tracer residence time in their vicinity due to diffusion toward weak bottom flows. The increased tracer residence time may explain the large vertical fluxes of heat and salt required to close the abyssal circulation.
Mixing in a coastal environment: 1. A view from dye dispersion
Journal of Geophysical Research, 2004
1] Dye release experiments were performed together with microstructure profiling to compare the two methods of estimating diapycnal diffusivity during summer and fall stratification on the continental shelf south of New England. The experiments were done in 1996 and 1997 as part of the Coastal Mixing and Optics Experiment. During the 100 hours or so of the experiments the area of the dye patches grew from less than 1 km 2 to more than 50 km 2 . Diapycnal diffusivities inferred from dye dispersion range from 10 À6 to 10 À5 m 2 /s at buoyancy frequencies from 9 to 28 cycles/hour. Diffusivities estimated from the dye and those estimated from dissipation rates in the companion paper by Oakey and Greenan [2004] agree closely in most cases. Estimates of diffusivities from towed conductivity microstructure measurements made during the cruises by Duda and Rehmann [2002] and Rehmann and Duda [2000] are fairly consistent with the dye diffusivities. The dye diffusivities would be predicted well by an empirical formula involving shear and stratification statistics developed by MacKinnon and Gregg [2003] from profiling microstructure measurements obtained at the same site in August 1996. All of the measurements support the general conclusion that the diffusivity, averaged over several days, is seldom greater than 10 À5 m 2 /s in the stratified waters at the site, and usually not much greater than 10 À6 m 2 /s. Severe storms, such as a hurricane that passed over the CMO site in 1996, can dramatically increase the mixing at the site, however.