Data for Evaluation of Models and Spatial Data Products
For evaluation of models and remotely sensed data products, we used eddy covariance (EC) flux tower data from the FLUXNET2015 dataset (https://fluxnet.fluxdata.org). Our study included data from 151 EC tower sites which belonged to the following 12 terrestrial biomes. We used two criteria to filter the data, following (33): (1) if more than 20% of the data in a given year was missing, the whole year was discarded, and (2) after this first step of processing, EC-tower sites with records for less than two years were completely discarded. EC-towers details are in the Table.S2.
To simulate global GPP, the following spatial data products were used: (1) meteorological data fields – radiation, air temperature, latent heat flux, and sensible heat flux – derived from the second Modern-Era Retrospective analysis for Research and Applications (MERRA-2), (2) MODIS satellite products including enhanced vegetation index (EVI) and normalized difference wetness index (NDWI), and (3) atmospheric CO2 concentration from the Earth System Research Laboratory Global Monitoring Division (https://www.esrl.noaa.gov/gmd/dv/site/). In addition, global GPP products were selected for comparison, including: EC-LU, revised EC-LUE, MODIS, MOD17 C6, PR, VPM, FLUXCOM, SVR, BESS, BEPS, and 10 TRENDY products.