Ok, time for an update. Since I’ve started down this path, the FuelGraph project started as a fire and fuel type visualization tool. Then it became a way to compare models (FBP and CFIS), but some of the original authors of those models felt I was playing a bit fast and loose with fuel moisture concepts. Fair enough. (Just because the FFMC tries to estimate fine fuel moisture content doesn’t mean it actually does a good job, particularly across vastly different vegetation types.)
So a major change and increase in profile was in order. I had come up with a nifty way to link up a couple of models to get away from some FBP system constraints, but to make it actually credible requires quite a bit more analysis and documentation. That got me diving in headfirst to the original FBP System experimental burn documentation – the famed experiments at Sharpsand Creek and Porter Lake and Summit Lake (near Prince George).
At this point I feel like it’s starting to come together. At what ‘it’ is is now termed, rather pretentiously, the ‘Canadian Conifer Pyrometrics’ system. Well, it couldn’t be the Next Generation FBP System, because that name refers to another body of work (I do hope this CCP stuff eventually gets accepted enough to be integrated as an option within the NG-CFFDRS; the details definitely need to be worked out still). In a nutshell, it’s CFIS meets FBP with some tweaks and a simple surface model to tie things together, displayed and controlled (thus far) using FuelGraph.
Here’s the sneak preview, recently presented at the fabulous 6th Fuels & Fire Behaviour Conference (Marseille, France):
After working with this a whole bunch and some good discussions with Marty and Miguel, we came to the conclusion that it isn’t appropriate to equate FFMC-derived fine fuel moisture content (mc) with mc from Rothermel’s FBO tables. So I’ve deleted this version of FuelGraph. Combining a reanalyzed crown fire initiation model with a surface fire model and crown fire spread model (from CFIS), this is turning into a much larger project named Conifer Pyrometrics, gradually turning (I think) into a component of the Next Generation FBP System.
I haven’t deleted the post for posterity sake, but have deleted the FuelGraph version that included both. It turned out to be a bit intellectually dishonest, and I certainly wouldn’t want any fire behaviour forecasts or projections to be blown because of this.
I’ve made a major overhaul of the FBP Graph tool, and have added the new(er) Cruz, Alexander, and Wakimoto CFIS spread rate equations – crown fire occurrence (so-called passive and active) and ROS. Since the new stuff takes us beyond the realm of FBP, a name change was in order; thus, FuelGraph! See Graph 3 for the new stuff; only available with WS/FFMC (not ISI). This is a beta version, so if you find errors or weirdness, please let me know. The rest of the FBPS-fuel type-based functionality still exists in Graphs 1 and 2.
I envision this as a helpful tool for Canadian agency fire behaviour specialists or fuel management specialists who are playing with non-standard fuel types or planning fuel treatment scenarios. The CFIS equations include some options for showing crowning threshold confidence intervals as well as options for toggling between a couple of different input options.
For the final version (v.4.0) I may add a another feature or two, but at this point I’m pretty content with this thing. Let me know what you think. Anyone who wants to look under the hood can unhide the calculation sheets and unprotect the graphs – send a note if you’d like to do that and I could send the password.
I finally got around to making some long-planned changes to FBP Graph, the MS Excel tool for comparing fire behaviour using the Canadian Fire Behaviour Prediction System.
The latest version has the subtle-but-significant change of showing (if the box is checked) fire type. That is, when checked, the graph lines now indicate three thresholds, in terms of ISI or wind speed: these are the crown fire initiation threshold (between surface fire and intermittent crown fire, or 10% Crown Fraction Burned, or CFB), the point at which CFB is 50%, and the threshold between intermittent and continuous crown fire (90% CFB). As with the rest of the FBP Graph tool, the point thresholds move around on the graph depending on fuel type, buildup index (BUI), and some other modifiers depending on fuel type.
These thresholds are important for two reasons. As fuel consumption and spread rate increase, conifer crowns become involved in fire spread (according to the Van Wagner crown fire model), further increasing fire intensity. However, the only fuel type in the FBP System that demonstrates a change in spread rate as crown involvement increases is the C-6 type, which is in many ways the most sophisticated fuel type in the system. So it is important to note where along the lines changes in fire type occur, as these can show where one can expect sudden changes in fire behaviour.
A second reason for the importance of these thresholds is that predicted rate of spread may well be incorrect as fire type changes. As many authors have noted, at the onset of crown fire initiation, spread rate can increase more than threefold, as the flaming front is suddenly exposed to above-canopy ambient winds. This change is not reflected in sigmoidal ROS curves that most FBP fuel types have, so fire type thresholds can indicate where these curves oversimplify, and likely underpredict, spread rate. As always, using the FBP Graph tool for operational purposes assumes expert knowledge and training in fire behaviour prediction using the CFFDRS, and I make no guarantees about the accuracy of the outputs (but you know, if you think there are errors, please let me know so I can address them). The ISI or wind speed threshold is calculated to the nearest 1 unit (ISI or km/h); so fire behaviour calculators such as RedApp are more accurate, but this is still pretty accurate given the inaccuracy of the base measurements (precipitation, wind speed, etc.). Thanks for your interest.