Each files contains 12 monthly mean for each year 1991 to 2100 of surface biomass (mmol C/m3):
Photosynthetic prokaryotes, pico-eukaryotes, coccolithophores, diazotrophs, diatoms; mixotrophic dinoflagellates; zooplankton.
Note that the atmospheric-ocean component of the earth system model used to produce the forcing fields has its own internal interannual variability. Though the frequency of phenomena such as ENSO are captured, they do not occur in same years as the real ocean
The model output list here was used in:
Bardon, L., B.A. Ward, S. Dutkiewicz, and B.B. Cael, 2021. On predicting plankton biogeography with machine-learning methods. Geophysical Research Letters, 48, e2021GL093455, doi:10.1029/2021GL093455