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Clear Air Turbulence


In December of 1992, a DC-8 cargo plane westbound out of Denver encountered severe clear air turbulence. Despite losing an engine (far right side) and 6 meters of wing the crew managed to land the plane safely.

This event - and others like it - are a strong reminder that we don't yet understand clear air turbulence nearly well enough. In this particular case, observational data revealed pronounced Horizontally-aligned Vortex Tubes (HVT). NCAR and NOAA researchers worked together to study the incident and using NOAA weather data, developed a very high resolution numerical model to see what a simulation might reveal.
         

Jetstream and Air Parcels

  

Enstrophy

  

VS, VRMS and Enstrophy
         

QuickTime | Real | MPEG 3.4MB

The view is from the southwest with the Rocky Mountains in white, the jetstream in blue and fast-moving parcels of air in yellow.

  

QuickTime | Real | MPEG 1MB

The yellow air parcels have been replaced by the enstrophy field in green.

 

QuickTime | Real | MPEG 63MB

Fields shown include VS (blue, 55m/s), VRMS (yellow, 10m/s), and Enstrophy (red, .1).

   
YouTube
    
Domain  
Subject:
 Turbulence
Atmosphere Layer:
 Stratosphere
Location:
 Boulder, Colorado USA
Horizontal Dimensions:
 48 km x 48 km
Vertical Dimensions:
 13.35 km
Horizontal Resolution:
 30 m
Vertical Resolution:
 72 levels, irregularly spaced
Data & Model  
Model Name:
 Clark Model
Dataset:
 Landsat Thematic Mapper
Data Size:
 1 TB raw, 128 GB byte-scaled, resampled and subsetted to about 10GB in a working set.
Variables Visualized:
 Jetstream, fast-moving air parcels, enstrophy, VS, VRMS
Start:
 December, 1992
Time Evolution:
 Subsetted to ~27 min, raw data ~6 hours
Time Resolution:
 7.5 seconds
Timesteps:
 219 in subset, ~2800 in overall dataset
Hardware:
 Cray J/932
CPU Time:
 1500 hours
Creation Software:
 POV raytracer, Vis5D
Research Project
Scientific Credit :
  • Terry Clark, Larry Radke, Bill Hall, Bob Kerr (NCAR)
  • F. Martin Ralph and Paul J. Neiman (NOAA/ERL/Environmental Technology Laboratory)
  • David Levinson (CIRES, University of Colorado/NOAA)
Visualization Credit :
  • Don Middleton (NCAR)
Date Catalogued:
 2002-08-05
Rights:
 © 2002, UCAR, All rights reserved.