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JGCRI / hector

The Hector Simple Climate Model
http://jgcri.github.io/hector/
GNU General Public License v3.0
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Proportional, not fixed, LUC losses #647

Closed bpbond closed 1 year ago

bpbond commented 1 year ago

In all versions of Hector to date, land use changes (emissions or uptake) cause carbon to leave (or enter) the terrestrial pools in fixed and user-definable fractions: f_lucv, f_lucd and implicitly f_lucs for the fraction from/to vegetation, detritus, and soil respectively.

However in #638 Dawn made the case that this is both ad hoc and uncertain, depending heavily on the exact disturbance type; and that it made more sense — was simpler and more conservative — to simply pull/add C proportionately to the pool sizes. This also has some nice properties in terms of the model's stability after a LUC pulse — see #646 #643 .

This PR makes this change, shifting the land model to use proportional LUC changes — from #639 — but now split into their own PR for easier evaluation.

Note that this is branched from #646 , as I assume we will definitely merge that.

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bpbond commented 1 year ago

This PR against the updated v3_dev, after merging #646 :

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bpbond commented 1 year ago

Oh interesting, look at the HL_pH panel above.

kdorheim commented 1 year ago

@bpbond could you please explain a bit more what you mean by "Proportional LUC" I want to make sure that I fully understand what is going on here and that our future selves will know what was meant by "Proportional LUC"

bpbond commented 1 year ago

@kdorheim Updated the primary comment above; is that more complete and clearer?

bpbond commented 1 year ago

Updated change-from-v3_dev plot:

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bpbond commented 1 year ago

Over to you @kdorheim for assessment and, if things look good, approval and merging.