Dvorak Intensity - help

[WXFIEND]

Well I know what Dvorak is and I've been trying to do some research but from what I've found (and i'm not sure if this is right)... it has to be done by a computer analyzig a sat. image using an algorithm.

Is this true? I know many ppl say "my dvorak estimate comes up with...." . Do they all have the special equation?

and if you can do it by yourself, can someone teach me? Thanks!

[Astro_man92]

PLease could you post a link to this site thank you

[Derecho]

Actually the original Dvorak technique, and it's still done by three agencies (TAFB, SSD, and the Air Force) is all done by human beings eyeballing satellite pics using a specific series of criteria.

Unfortunately the technique is not fully explained on the web. I believe the full technique is explained in an old paper by, of course, Dvorak, that you'll have to track down in a large library or order somewhere.

I think what you're talking about is the ODT (objective Dvorak technique) which does use a complex computer algorithm.

You'll find info about it here:

http://cimss.ssec.wisc.edu/tropic/resea ... k/odt.html

[WXFIEND]

yeah thats the one. ODT.

I jujst got fascinated on the NWS site with the "DVorak satellite" ... but apparantly its not that easy and i could not be able to do it myself... I guess its best left to pro. mets?

[Derecho]

The plain old non-computerized Dvorak isn't brain surgery or anything, actually the technique is pretty simple, but you need the documentation; also I believe there's a set of comparison satellite shots you use too.

You use the "Dvorak" satellite shots only on strong hurricanes with well developed eyes; that sat shot is set up so you can see tiny differences in the temps of the cloud tops right around the eye; that's primarily what determines T numbers once you get real high, above T 6.0.

The ODT is pretty complex from what I understand, not a simple computer program.

The thing about the ODT is that while the original hand-done Dvorak stops at 8.0, you can get ODT numbers above 8.0; the record is 8.7.

[Derecho]

If anyone is interested in doing their own Dvoraks you'll likely need these three pubs (I meant to get them at some point, never got around to it; I live near Washington DC, so I have no excuse.)

Dvorak, V., 1975: Tropical cyclone intensity analysis and forecasting from satellite imagery. Mon. Wea. Rev., 103, 420-430.

Dvorak, V., 1984: Tropical cyclone intensity analysis using satellite data. NOAA Tech. Report NESDIS 11. Available from NOAA/NESDIS, 5200 Auth Rd., Washington DC, 20233, 47pp.

Dvorak, V., 1995: Tropical clouds and cloud systems observed in satellite imagery: Tropical cyclones. Workbook volume 2. Available from NOAA/NESDIS, 5200 Auth Rd., Washington DC, 20233.
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[wxman57]

I had saved a document on the Dvorak technique that someone sent over on a hurricane group mailing list. Here it is in PDF format. Probably explains it better than any web site I've found. It's not the full technique, just notes on performing an analysis:

http://myweb.cableone.net/nolasue/dvorak.pdf

Here are a few other links with info:
http://www.comet.ucar.edu/class/satmet/ ... sld074.htm

Some talks from the AMS converence in Miami that I atteneded last year:
http://ams.confex.com/ams/26HURR/techpr ... _16936.htm