Simulation 2: Maximum simulated radar reflectivity, overlaid with 1000-meter horizontal wind vectors. Colors indicate the reflectivity (in units dBZ) that a network of radars would observe if located across the ocean and nearby land. Warmer colors (higher dBZ) generally indicate more intense precipitation. ABOUT THE VISUALIZATIONS IN THIS PLAYLIST These visualizations show how the NCAR-based Advanced Hurricane WRF (Weather Research and Forecasting Model) has depicted various aspects of Hurricane/Superstorm Sandy unfolding over four days (96 hours) in October 2012, from 1200 GMT / 8:00 am EDT 10/26/12 to 1200 GMT / 8:00 am EDT 10/30/12. The model simulations were updated every second. In these videos, each frame is separated by 30 minutes of model time. Each video includes a full-frame visualization, followed by a zoomed-in version of the same sequence that shows the highest-resolution results (500 meters between points). All videos include vectors that show horizontal wind speed and direction at 1000 meters (about 3300 feet) above mean sea level. The length and color of the wind vectors correspond to wind speed (legend not shown). Longer vectors denote stronger winds. ABOUT THE COMPUTER MODELING Researchers began with observations collected at the beginning of the four-day period. They started, or initialized, the AHW model with those data. The model itself, which captures the atmospheric physics associated with hurricanes, then predicted Sandy's behavior over the following four days. The resulting "hindcast" (a forecast conducted after the fact) closely matches the actual behavior of the hurricane/superstorm. The modeling was performed using the Blue Waters Cray XE6 supercomputer at the National Center for Supercomputing Applications (NCSA). The simulation and resulting visualizations are among the most detailed ever conducted for a particular hurricane, with conditions tracked every 500 meters (about 1,600 feet) horizontally. Since the model includes 150 vertical layers, this means that weather conditions were calculated at more than four billion points for each second in the 96-hour simulation. Related story: http://www2.ucar.edu/atmosnews/opinion/10150/new-views-sandy CREDITS Science: Mel Shapiro and Thomas Galarneau, NCAR Visualization: Alan Norton, NCAR, using VAPOR (Visualization and Analysis Platform for Ocean, Atmosphere, and Solar Researchers: http://www.vapor.ucar.edu/) Simulation: Mark Straka, NCSA, and Peter Johnsen, Cray Inc. Postproduction: Perry Domingo, NCAR

• published: 26 Sep 2013
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