This data is an ensemble of Joint UK Land Environment Simulator (JULES) simulations, ran for a select set of 1kmx1km grid cells in Great Britain, each with a different set of parameter values, from 2001 to 2010. The data includes simulated Gross Primary Productivity (GPP) for 5 different plant functional types on an 8-day average. (Broadleaf trees, Needleleaf trees, C3 grasses, Shrubs, and Cropland) as well as the weighted combined sum. These simulations were obtained to facilitate statistical emulation, which is why a wide range of grid cells and parameter values were used (both also provided in the data set). The work was funded by the Natural Environment Research Council through research grant NE/T004177/1 JULES EMulator of ecosystem services (JEM) Full details about this dataset can be found at https://doi.org/10.5285/789bea37-0450-4822-9857-3dc848feb937