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HighlightsUnderstanding Heat Transport in Ocean Simulations will Improve our Understanding of Climate Change --> movie available>>>>>Movie Download<<<<< Movie Captions Eddies transport heat from the Equator to the Poles; they are important to the world's climate. We focus on one of the climate community's canonical methods for identifying eddies: the Okubo-Weiss parameter. In general, this parameter divides the ocean into regions dominated by vorticity, regions dominated by strain or deformation, and a background where neither effect is dominant. Regions dominated by vorticity are potentially eddies, though vorticity dominance can be caused by other effects, such as sharp turns in the mean flow. Because Okubo-Weiss is difficult to interpret directly, it has been normalized to its standard deviation and colored based on the oceanographic rule of thumb that the significant activity is 0.2 standard deviations from 0. In this movie, we visualize the Okubo-Weiss parameter by removing all voxels in the three-dimensional simulation data above the −0.2 standard deviations threshold. The remaining voxels, which according to Okubo-Weiss comprise the eddies and other high-vorticity features, are then painted as solid cubes colored by normalized Okubo-Weiss value, from red (lower vorticity) to yellow (higher vorticity). These high-vorticity features are placed on a 3D bathymetric map of the ocean floor also extracted from the simulation data. The three-dimensional shapes of the eddies are now made clear: here in a region containing the Gulf Stream, several strong eddies reach very deeply into the ocean, while smaller eddies remain near the surface, and the Gulf Stream dominates near the surface. Understanding Heat Transport in Ocean Simulations will Improve our Understanding of Climate Change
the Okubo-Weiss (ow) parameter, (stretching strain)2 + (shear strain)2 - (vorticity)2 Impact -Having a better understanding of heat transport in the ocean will improve our understanding of the effects of global climate change -Identifying eddies allows empirical comparisons between simulations and observations, increasing our trust in our simulations Scientific Visualization Critical for Quickly Finding Cosmological Simulations Coding ErrorsProblem -Difficult to find subtle coding mistakes in complex cosmological simulations -Existing statistical and numerical analysis checks do not always identify these errors Solution -Visualizing the results of an erroneous code can quickly reveal subtle errors -In the cosmology simulation below, a coding error caused velocity vectors with extremely large y-components, shown as long red arrows -The cosmologist writing the code says, "...the first test I always do for checking new code developments in detail is visualizing the particles and their velocities. You very quickly get a large amount of information and understand much more intuitively what is going on. It is very helpful." Impact -Visualization plays a key role in producing verified simulation codes Erroneous Simulation Output Visualization Reveals the Errors Corrected Output Automated distance visualization reduces time to visual understandingProblem Climate scientists at LANL perform daily simulations at ORNL. It takes minutes to hours of their time (approximately 23 minutes per one full resolution, single field data set) to copy the data for local analysis. Solution Automatically compress data after it is generated with data precision guarantees. The remote simulation data is tracked, managed, and pre-loaded into the scientist’s visualization tool for fast local access at a desired accuracy. Impact Data is automatically available on the scientist’s desktop for local viewing increasing productivity. Our approach reduces the network transfer time to seconds/minutes with a guaranteed maximum data error for visualization and analysis. Mat Maltrud, Ocean/Climate Scientist, LANL: "This new distance visualization technology will increase our productivity by significantly reducing the amount of time spent in analyzing our remote data." |