Ocean Models By Tom Snyder

Outline Beginning Ripples Modeling the Motion in the Ocean A Sea of Math The Next Wave

Ocean Models are difficult to portray What are Ocean Models A representation of information about Oceans Ocean Models are difficult to portray Eddies, multi-layered, interference, lots of information, constant change So why do Ocean Modeling Large effect on Earth’s weather / climate. Ship routing, long range forecasting How is this related to Computational Science

Types of models Free Surface Models Rigid Lid Models Z-level Models

Free Surface and Rigid Lid Models Real oceans have deformities due to temperature, wind, tidal force, etc. To include these deforming wind driven waves impairs the ability to do more accurate long term forecasting Rigid Lid models put a Tupperware™ lid over the ocean. Free Surface Models Deals with the top “layer” of the ocean and all the deformities Useful for short term studies

Z Level models Any model that separates the ocean into distinct layers

Reduced Gravity Models Looks at a layer or layers of the ocean that has a specific depth and ignores all motion below that. Interesting fact about these models is that the deviations of the interface between the two layers are multiples of the free surface elevation, by a factor which is proportional to the ratio p/∆p Z-level model

Mixed Layer Models Modeling of the top turbulent levels of the ocean. Separates into distinct layers of reasonably similar salinity and temperature. Must cope with the turbulence of the upper ocean.

Sigma-Coordinate Model Another way of looking at Z level models Better because it handles shallow areas better Worse because it has a harder time managing the “steep” areas calculation of the pressure gradient terms in the momentum equations

More math that you can shake a stick at Each model has it’s own set of equations that represent differences in the ocean and handles certain situation in their own way All must handle mass transports, grid spacing, time dependency Differences in “steep” area between Z level models and Sigma Coordinate model There are a set of equation that are more universal. Friction (between various things), turbulence due to bottom topology Plus a set of equations that deal with problems for certain models Free surface elevation, Wind stress, Bottom stress

Computational Problems due to these inconsistencies Change verses time/depth Eddy solutions Resolution verses Runtime Complexity

News about current models The progression of technology and algorithms has a direct impact on the resolution that can be achieved. New models are developed all the time for specific situations

Exercises Go to Goolge.com Search for “Ocean Models” to learn more about different types of Models http://www.navo.hpc.mil/visualization/noframes/scivi112.html Talks about high resolution and it’s importance for Ocean Models Optimum Thermal Interpolation System (OTIS) http://www.fnoc.navy.mil/otis/archive/otis_archive.html