Convex parameter

[penguian]

keyword_nogit resolution_fixed type_defect | by mgk576

---

The convex parameter which that sets the curvature of the light-response curve of electron transport is set to 0.01 for all PFTs in CABLE except C4 grasses (0.4). This must surely be a bug, as a typical value used in models would be 0.7. I note that in Vanessa's recent paper she has changed it to 0.85.

Setting the value this low would severely reduce the responsiveness of GPP to increasing CO2, so ought to be fixed for CMIP runs I would suggest!

I asked YP and he didn't know the origin of this value and agreed that 0.7 would be more standard. I suggest unless anyone can trace this and has a good justification, that we fix this soon as it strikes me as a bug.

---

Issue migrated from trac:202 at 2023-11-27 11:26:57 +1100

[penguian]

@mgk576@nci.org.au changed owner from bep599 to somebody

[penguian]

@mgk576@nci.org.au changed component from MPI to biogeophys

[penguian]

@mgk576@nci.org.au commented

---

Sorry that 0.4 should be 0.8, for what it is worth and I should have set component to biogeophys. I can't seem to find a function to edit the ticket

[penguian]

@mgk576@nci.org.au commented

---

von Caemmerer, S. (2000) Biochemical Models of Leaf Photosynthesis, pg 35, suggests a value of 0.7, citing Evans, J. R. (1989) Photosynthesis and nitrogen relationships in leaves of C3 plants. Oecologia, 78, 9-19.

[penguian]

@jxs599@nci.org.au changed status from new to closed

[penguian]

@jxs599@nci.org.au changed resolution from ` tofixed`

[penguian]

@jxs599@nci.org.au commented

---

The CMIP6 version has been updated to use 0.7 as suggested

[penguian]

@jxs599@nci.org.au changed milestone from ` to1. Closed`

[penguian]

@ccc561@nci.org.au set keywords to nogit