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| In meteorology the '''Ellrod index''' is a technique for forecasting [[clear-air turbulence]]. It is calculated based on the product of horizontal deformation and vertical [[wind shear]] derived from numerical model forecast winds aloft.
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| The deformation predictors are calculated using following information.
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| * ''Shearing deformation'':
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| : <math>DSH=\frac{dv}{dx} + \frac{du}{dy} </math>.
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| * ''Stretching deformation'':
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| : <math>DST = \frac{du}{dx} - \frac{dv}{dy}</math>.
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| Where ''u' and ''v'' are horizontal components of the wind.
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| * ''Total deformation'' equals to:
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| : <math> DEF = \sqrt{DSH^2 + DST^2} </math>.
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| * ''Convergence'':
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| : <math> CVG = -(\frac{du}{dx} + \frac{dv}{dy}) </math>
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| * ''Vertical wind shear'':
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| : <math> VWS = \frac{\Delta V}{\Delta Z} </math>
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| And the resulting index is given by:
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| : <math>EI = VWS \times (DEF + CVG) </math>
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| To correspond to clear-air turbulence [[pilot report]]s the following table can be used:
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| {| class="wikitable" style="text-align:center"; border="5"
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| ! Reported !! EI value threshold
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| |-
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| | Light-Moderate || 4
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| |-
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| | Moderate || 8
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| |-
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| | Moderate-Severe || 12
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| |}
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| * [http://aviationweather.gov/exp/ellrod/info.php?mdl=NAM Aviation Weather Center Help ]
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| * [http://aviationweather.gov/exp/ellrod/nam/ Aviation Weather Center EI display ]
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| [[Category:Basic meteorological concepts and phenomena]]
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| [[Category:Turbulence]]
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My name's Eduardo Lajoie but everybody calls me Eduardo. I'm from Germany. I'm studying at the college (2nd year) and I play the French Horn for 3 years. Usually I choose music from the famous films :).
I have two brothers. I love Sculling or Rowing, watching TV (The Simpsons) and Skateboarding.
Feel free to surf to my page ... wordpress dropbox backup