Upper Air Indices - Differences

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AB5R
Junior Member
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Joined: Thu Apr 24, 2008 9:18 pm
Location: Grandview, TX 76050

Upper Air Indices - Differences

Post by AB5R »

Can anyone explain why Upper Air Plots from Unisys, SPC and Digital Atmosphere will have different numbers for various indices? Would RAOB be any more credible?

Thanks
Greg Higgins
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Joined: Sun Nov 30, 2003 5:05 am
Location: Fort Worth, TX

Post by Greg Higgins »

Part of it depends on what parcel is being lifted (i.e., MU-most unstable, surface based, etc.), what time was the sounding obtained (not all are 00z and 12z) and if they are based on a model (for 2-3 days out). RAOB is an excellent program and allows many functions to be determined by the user.

Greg Higgins
Tim Vasquez
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Joined: Sat Nov 22, 2003 10:47 pm

Post by Tim Vasquez »

If you're talking about upper air plots (i.e. a horizontal map), the final output is very sensitive to the conditions of the original analysis.

First there are two ways of doing this.

The easiest way is to take the LI at each individual station and then just analyze it horizontally across the map domain. Some sources may do that.

Other sources (including Digital Atmosphere) will analyze the temperature and moisture at different levels, in this case the lowest levels of the atmosphere and 500 mb, and then generate LI across those fields using a grid. That too will generate different results from different sources because no particular analysis field is dead-on, and the differences can magnify when you are computing across multiple fields.

Tim
AB5R
Junior Member
Posts: 9
Joined: Thu Apr 24, 2008 9:18 pm
Location: Grandview, TX 76050

Upper Air Indices - Differences

Post by AB5R »

Thanks to each of you for answers. I simply downloaded the same upper air report from each source and ran one with Digital Atmosphere too. Some numbers agreed and others did not. I was just wondering why. I assume that all were Mixed Layer outputs. (I could be wrong here.)

Obviously, I am a newbie trying to learn, The Upper Air skew-T charts are my focus right now. I have bought the RAOB software and waiting for the Manual. Can anyone suggest a tutorial book specifically on this subject??

Thanks again,
Jerry
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