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Output results differ between 6.2 and 6.7 using same data and parameters

Started by Beneke, October 24, 2016, 06:38:52 AM

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Hi Jonathon, Amy and Marco.  I've been using different versions of SLAMM for the last three years and believe I have fairly good skills and knowledge to operate it. Recently, I downloaded v6.7 and because it appears to have many changes compared to v6.2 I wanted to see if both had the same output results if I used the same data and parameters. The initial condition is the same for both, but for each time step the changes / differences between each vegetation class is sometimes in the thousands of hectares as each time step is increased up to 2100. Can you give any explanation for this?

I've attached two excel files from each version. I can also provide the parameters if needed.

Thanks, Brian

Jonathan S. Clough

Yes, we'll look into this and get back to you shortly!  -- Jonathan

Jonathan S. Clough

Thanks -- I have looked at the numbers and they are indeed different (of course).

What I cannot do is verify why, unless I have your SLAMM6 projects, I'm afraid.  Right now I suspect it is something to do with the connectivity options on the Execute screen (whether to average 4 or 8 cells, for example, or whether to use the min or mean cell elevations. 

One thing we did when creating 6.7 was to verify output against the previous version.  Which was version 6.6 (internal version).  So the difference could be between 6.2 and 6.6.  If you send me your SLAMM6 files I'll have a better chance to track this down.

Best regards -- Jonathan


I think you were on to something on the connectivity because it wasn't used at all in v6.7. I then ran both v6.2 and 6.7 with the connectivity off and still got some major differences in a few vegetation categories. I've attached both here for you to look at and give me any suggestions.