The maximum rate of Rubisco carboxylation (Vcmax) determines leaf photosynthetic capacity and is a key
parameter for estimating the terrestrial carbon cycle, but its spatial information is lacking, hindering global ecological
research. Here, we convert leaf chlorophyll content (LCC) retrieved from satellite data to Vcmax, based on plants’ optimal
distribution of nitrogen between light harvesting and carboxylation pathways. We also derive Vcmax from satellite (GOME-2)
observations of sun-induced chlorophyll fluorescence (SIF) as a proxy of leaf photosynthesis using a data assimilation
technique. These two independent global Vcmax products agree well (r
2=0.79, RMSE=15.46 μmol m-2
s
-1 25 , P<0.001) and
compare well with 3672 ground-based measurements (r2=0.68, RMSE=13.55 μmol m-2
s
-1
and P<0.001 for SIF; r2=0.55,
RMSE=17.55 μmol m-2
s
-1 and P<0.001 for LCC). The LCC-derived Vcmax product is also used to constrain the retrieval of
Vcmax from TROPOMI SIF data to produce an optimized Vcmax product using both SIF and LCC information. The global
distributions of these products are compatible with Vcmax computed from an ecological optimality theory using meteorological variables, but importantly reveal additional information on the influence of land cover, irrigation, soil pH and
leaf nitrogen on leaf photosynthetic capacity. These satellite-based approaches and spatial Vcmax products are primed to play a
major role in global ecosystem research. The three remote sensing Vcmax products based on SIF, LCC and SIF+LCC are
available at https://doi.org/10.5281/zenodo.6466968 (Chen et al., 2020) and the code for implementing the ecological
optimality theory is available at https://github.com/SmithEcophysLab/optimal_vcmax_R (Smith, 2020).