Company Background:
Space-Time Toolkit and the Anderson Hills Tornado

The application shown below utilized the Space-Time Toolkit to visually show correlations between various meteorological data sets associated with an F4 tornado in Madison County, Alabama on May 18, 1995. This deadly tornado destroyed large sections of the Anderson Hills subdivision. The tool used the following data sets in their "original" real-time format, that is, with no preprocessing to put the data into a common spatial or temporal grid:

• GOES Satellite data in a Mercator map projection with 15 minute temporal resolution
• OTD (Optical Transient Detector) satellite visible light images in raw CCD sensor space with 1 minute temporal resolution
• OTD lightning events in raw sensor space with roughly 10 msec temporal resolution
• SSM/I (Special Sensor Microwave/Imager) satellite data in raw conical-scanner sensor space
• Doppler radar data in raw conical elevation/azimuth/range radial format
• NWS (National Weather Service) radar in raw elevation/azimuth/range per-beam format
• CONUS (continental US) precipitation image in an Equirectangular map projection with 15 minute temporal resolution
• CONUS ground strike lightning events with 1 second temporal resolution
• tornado ground path based on NWS weather reports and aircraft observations
• state and county boundaries.

A unique feature of this tool, provided automatically by the Space-Time Toolkit's flexible time architecture, is the visual display of the NWS radar's sweeping motion. When the time step for the tool is set below the radar's full sweep period, then the radar beam can be watched as it progressively sweeps around. When the time step is set above the radar's full sweep period, then each time increment will fully render the complete sweep without showing the beam's progress.

The two screen images below show the Space-Time Toolkit's critical ability to display only the visually necessary datasets given the tool's zoom-level and accuracy-versus-interactivity settings. The first image shows only the CONUS composite precipitation and OTD lightning strikes because the other datasets are too small to be seen when zoomed-out. The second image shows all of the first image's data plus the more detailed radar and lightning data that's visible only when zoomed-in close. The Toolkit's "accuracy on-demand" feature is important when providing interactive access to large amounts of data, as there's little point in drawing huge amounts of data that can't be clearly seen.

Zoomed-out view of the Anderson Hills tornado, showing cloud-to-cloud lightning (red dots) detected from the OTD satellite as well as the CONUS precipitation product (shades of blue and purple.)  The OTD's observational footprint (the bowed-in square outline) and its orbital track are depicted as thin gray lines.