2.7 | Model comparisons
To compare the PRELES estimates for 2012 and 2013 to the GPPiso/SF estimate, we first chose to calculate GPPiso/SF based on gm/\(g_{C\hat{\alpha}}\) = 2.67 (Stangl et al. , 2019). The constant ratio assumption is widely used in the literature (Klein et al., 2016; Seibt et al., 2008). Second, we tested the GPPiso/SF estimate in the F plot against the R plot. Finally, the annual sums were calculated and compared for GPPiso/SF and GPPPRELES in 2012 and 2013. We combined 2012 and 2013 in order to estimate the inter-annual variability of the different approaches. The standard deviation (SD) was calculated from the mean annual sum in 2012 and 2013.