Chandler Burning Index computed by a virtual sensor

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d_l
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Chandler Burning Index computed by a virtual sensor

Post by d_l » Wed Jul 26, 2017 5:49 pm

I wanted to compute the Chandler Burning Index with a virtual sensor. It took more than a few trial-and-error attempts to get it to work and I thought others might be interested in a "how-to".

First of all, this computation is using Meteohub version 4.6t (I don't update often).

For your virtual sensor, define the following:
New ID - data#
Name - CBI or what ever you wish
Trigger - th#
Conversion - awk ' { printf ''%d'', ((((110 - 1.373 * $4) - 0.54 * (10.20 - $3 / 10)) * (124 * 10 ** (-0.0142 * $4))) / 60) * 100 } '

The Chandler Burning Index formula is CBI = (((110 - 1.373*RH) - 0.54 * (10.20 - T)) * (124 * 10^(-0.0142*RH)))/60. Note that the temperature must be divided by 10 and the overall index number multiplied by 100 to produce the correct value. I also could not get the exponentiation symbol "^" to work. It errored as "_". So I switched the formula to a double asterisk "**" which is supposed to be equivalent to "^".

For now, I've been plotting the CBI on a simple 24 hr graph with an explanation of the different color code levels underneath the graph - https://www.tceweather.com/firedanger_graph.html. When I get the time, I'd like to add the fire danger level color codes to the graph some how.

Edit: Fixed the graph link to the permanent version fron the temporary testing one.

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