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.