Collaborative Research: Numerical Modeling of the Internal-Wave Cascade and Submesoscale Lateral Dispersion in the Ocean

GSTDTAP

项目编号	1536439
	Collaborative Research: Numerical Modeling of the Internal-Wave Cascade and Submesoscale Lateral Dispersion in the Ocean
	Miles Sundermeyer
主持机构	University of Massachusetts, Dartmouth
项目开始年	2015
	2015-12-01
项目结束日期	2018-11-30
资助机构	US-NSF
项目类别	Standard Grant
项目经费	283425(USD)
国家	美国
语种	英语
英文摘要	Lateral stirring is among the fundamental processes, along with advection and diapycnal (vertical) mixing that determines the distribution and fate of water-mass properties, nutrients and dissolved gases in the ocean. Ocean general circulation models (OGCMs) resolve stirring on scales larger than ~30 km, and regional models on scales ~1 km, but isopycnal (lateral) stirring by submesoscale (1 to 10 km) and finescale (10 m to 1 km) processes must be parameterized. Tracer-release experiments consistently find isopycnal diffusivities at scales of 1-10 km to be an order of magnitude larger than predictions for internal-wave shear dispersion. This project will provide a more complete and accurate assessment of the roles of internal waves and vortical mode in lateral stirring at the submesoscale of order 10 m to 10 km), and the cascade of energy to dissipative vertical scales, to resolve this paradox. Internal waves and vortical mode are difficult to distinguish observationally. However, judicious use of a numerical model can tease apart their influences by isolating different physics. A major advantage of the approach of this project is that all of the above processes/dynamics can be explored in the context of a single model, allowing us to seamlessly explore the internal-wave cascade and lateral dispersion by the different mechanisms across a wide range of parameter regimes and forcing conditions. The proposed simulations will elucidate the underlying physics and inform our understanding of how these processes work in the ocean so as to provide an order-one parameterization of submesoscale isopycnal diffusivities for OGCMs. Parameterizations developed in this study will be made available through peer-reviewed publications and conference presentations. Two graduate students will be trained in high resolution numerical modeling and data analysis techniques. A public project website will also be maintained, with initial conditions and parameters for our simulations archived and shared on request with other investigators interested in collaboration. The proposed approach will use a Boussinesq pseudo-spectral model to investigate lateral dispersion and the internal-wave energy cascade. Specific goals are to determine the roles of (1) wave/wave and wave/vortex interactions in the internal-wave cascade to small vertical scales and turbulence production, (2) wave/wave and wave/vortex de-phasing of the internal wave field in isopycnal stirring, (3) turbulent intermittency in internal-wave shear dispersion, and (4) vortical-mode shear dispersion and stirring. Model results will also be used to examine (5) the physics of the finescale roll-off and (6) the statistics of unstable shear events (Richardson number less than a quarter). Simulations with and without finescale potential vorticity production by internal-wave breaking will be used to isolate the roles of the vortical-mode inverse cascade. Passive tracers subject to diapycnal mixing and non-diffusive Lagrangian particles will be used to distinguish between shear dispersion and stirring. The simulations will be run with varying buoyancy frequency, Coriolis frequency, internal-wave spectral energy level and frequency spectral shapes to explore fundamental parameter dependences of the cascade, finescale roll-off, Richardson Number statistics, diapycnal diffusion and isopycnal diffusion. First-order submesoscale horizontal diffusivities for OGCMs and regional models will result. Different forcings (surface wind, tidal) for maintaining the internal-wave field in a statistically steady state will be tested. Profiling float and dye data collected in the Sargasso Sea during summer will be used to guide model initialization and assess the realism of the results. Where possible, differences in modelled dispersion characteristics will be identified and used to identify stirring mechanisms in the observational data sets.
来源学科分类	Geosciences - Ocean Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/68979
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Miles Sundermeyer.Collaborative Research: Numerical Modeling of the Internal-Wave Cascade and Submesoscale Lateral Dispersion in the Ocean.2015.