A triple tree-ring constraint for tree growth and physiology in aglobal land surface model

Abstract. Annually-resolved tree-ring records extending back to pre-industrial conditions have the potential to constrain the responses of global land surface models at interannual to centennial time scales. Here, we demonstrate a framework to constrain the representation of tree growth and physiology in the ORCHIDEE global land surface model using the simulated variability of tree-ring width and carbon (Δ13C) and oxygen (δ18O) stable isotopes in six sites in boreal and temperate Europe. We exploit the tree-ring triplet to derive integrative constraints for leaf physiology and growth from well-known mechanistic relationships among the variables. The model simulates Δ13C (r = 0.31–0.80) and δ18O (r = 0.36–0.74) better than tree-ring width (r