The WRF-ARW simulation employs up to 6 telescopic nested grids with resolutions from 15 km to 62 m. The innermost domain (5th or 6th) has 601x601x50 grid points. VAPOR's multiresolution data representation facilitates an understanding of hurricane dynamics by combining interactive visual exploration of volume data fields with interactive flow integration. Three visualization experiments are described, employing interactive visualization to provide insight into the results of high resolution WRF simulations. These experiments are performed interactively by initially performing visualization and flow integration at lowered resolution, then performing flow integration at full resolution on smaller regions of interest.
Comparison of volume renderings of velocity (of 5-level nesting on a 185 m grid versus 6-level nesting, on a 62-meter grid) identifies energetic turbulent eddies in the boundary layer under the eyewall that do not appear in 5-level nesting. The length scale and time scale of the large eddies can be easily characterized using volume rendering and isosurfaces with VAPOR on a sequence of WRF model output.
To better understand the behavior of the large eddies in the eyewall, the background (1-minute average) wind velocity is subtracted from the wind vector field, and flow integration is then performed on the resulting differences. This reveals a complex pattern of vortical motion, with numerous vortices in various orientations.
Unsteady flow integration in VAPOR, performed backward and forward in time, is a powerful tool to identify the origins of energetic air parcels in the eyewall. Scientific understanding is accelerated by interactively testing hypotheses and visually examining the results in 3D.
Supplementary URL: http://vis.ucar.edu/~alan/ams09/