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 Post subject: Stability Scripts
PostPosted: Mon Mar 14, 2005 9:41 pm 
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Joined: Mon May 10, 2004 10:01 pm
Posts: 44
Location: Pinner, Middlesex. UK
Hi Folks

I thought you might be interested in a couple of stability indecies that I have been playing around with.

Boyden Index (BI)

The Boyden index has been developed to allow better diagnosis of frontal thunderstorms and is tailored for use in cool, moist climates such as North Western Europe, no humidity information is included in the calculation. The index is calculated using the following formula:
BI=(H700-H000)/10-T700-200

In which H700- 1000 is the thickness of the layer between 700 and 1000 hPa in decametres, T700 the temperature (in degrees Celsius) at 700 hPa. Scaling factor 200 is used to bring the absolute values of the Boyden index close to a range from 90 to 100. Since the index doesn't contain surface temperature information, there is little variation between continental and marine air masses. The diurnal variation is also small. It is especially useful with cloudy conditions near fronts, when values of 94 or greater imply probable thunderstorms.

The higher the value of the Boyden index, the greater the risk of thunderstorm. The threshold value is approximately 95.

CONT GRTN 94 CINT=2 DASH COLOR=200:0:0 SSBC=6:200 STOR=6 SDIF 5:3 STOR=5 SDVC 4:10 STOR=4 SDIF 2:1 STOR=3 TEMP H700 STOR=2 HGHT H700 STOR=1 HGHT H000


KO Index

The KO Index is a stability index tailored for use in cool, moist climates such as Northwestern Europe. The formula is:-

The formula is:- Pt500+Pt700)/2-(Pt850+Pt1000)/2

Where the Pt are the equivalent potential temperatures at 500, 700, 850, and 1000 mb. Values over +6 suggest little if any shower activity, while values <2 imply possible thunderstorms.

>6 No Thunderstorms
2 - 6 Thunderstorms possible
<2 Severe Thunderstorms possible

CONT LSTN 6 CINT=2 DASH COLOR=200:100:100 SDIF=7:8 STOR=8 SDVC 6:2 STOR=7 SDVC 5:2 STOR=6 SSUM 3:4 STOR=5 SSUM 1:2 STOR=4 THTE H000 STOR=3 THTE H850 STOR=2 THTE H700 STOR=1 THTE H500


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PostPosted: Tue Mar 15, 2005 9:48 pm 
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Joined: Sun Nov 23, 2003 4:34 pm
Posts: 88
Location: Leverkusen, GERMANY
Hallo Peter,

thanks so much - very helpful scripts - specially for us here in europe.

Stefan


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