Input data set: GFDL-MOM6-COBALT2 (ocean)

Monthly, gridded (0.25° and 1° grid) oceanic forcing data covering the period 1961-2010.

To let observations at least indirectly enter the oceanic forcing data for ISIMIP3a, we provide outputs from an ocean model run that is forced by an observation-based reanalysis product of atmospheric forcing (Liu et al., 2021). Oceanic forcing data based on the latest GFDL-MOM6 and COBALTv2 physical and biogeochemical ocean models running on a tripolar 0.25° grid and using the JRA-55 reanalysis (Tsujino et al., 2018) as the surface forcing.

Simulations also account for dynamic, time-varying river freshwater and nitrogen inputs that were simulated based on GFDL's land-watershed model LM3-TAN (Land Model version 3 with Terrestrial and Aquatic Nitrogen) (Lee et al., 2019), adjusted using observations from the Global Nutrient Export from WaterSheds (NEWS) database (Seitzinger et al., 2006). To create the default ‘obsclim’ climate-related forcings for the fisheries and marine ecosystem models these ocean model simulation data have been interpolated to a regular 0.25° grid while vertical resolution is preserved.

We currently do not provide counterfactual versions of the ocean data forcing, though options are being explored.

To set-up climate-forcing variables for the entire 1841-1960 period, we ask modellers to use the "control run" (ctrlclim) monthly output for the years 1961-1980 (inclusive) on repeat for six cycles. These years have been selected because they correspond with an entire ENSO cycle and because no climate trend is detectable prior to 1980 from the GFDL model.

- Liu, X., Stock, C. A., Dunne, J. P., Lee, M., Shevliakova, E., Malyshev, S., and Milly, P. C. D.: Simulated global coastal ecosystem responses to a half‐century increase in river nitrogen loads, Geophys. Res. Lett., 48, https://doi.org/10.1029/2021gl094367, 2021.

- Tsujino, H., Urakawa, S., Nakano, H., Small, R. J., Kim, W. M., Yeager, S. G., Danabasoglu, G., Suzuki, T., Bamber, J. L., Bentsen, M., Böning, C. W., Bozec, A., Chassignet, E. P., Curchitser, E., Boeira Dias, F., Durack, P. J., Griffies, S. M., Harada, Y., Ilicak, M., Josey, S. A., Kobayashi, C., Kobayashi, S., Komuro, Y., Large, W. G., Le Sommer, J., Marsland, S. J., Masina, S., Scheinert, M., Tomita, H., Valdivieso, M., and Yamazaki, D.: JRA-55 based surface dataset for driving ocean–sea-ice models (JRA55-do), Ocean Model., 130, 79–139, https://doi.org/10.1016/j.ocemod.2018.07.002, 2018

- Lee, M., Shevliakova, E., Stock, C. A., Malyshev, S., and Milly, P. C. D.: Prominence of the tropics in the recent rise of global nitrogen pollution, Nat. Commun., 10, 1437, https://doi.org/10.1038/s41467-019-09468-4, 2019.

- Seitzinger, S., Harrison, J. A., Böhlke, J. K., Bouwman, A. F., Lowrance, R., Peterson, B., Tobias, C., and Van Drecht, G.: Denitrification across landscapes and waterscapes: a synthesis, Ecol. Appl., 16, 2064–2090, https://doi.org/10.1890/1051-0761(2006)016[2064:dalawa]2.0.co;2, 2006.

For ISIMIP participants, these files are available for download from the DKRZ server using the path /work/bb0820/ISIMIP/ISIMIP3a/InputData/climate/ocean/

For external users, these data can be downloaded from the ISIMIP Repository using the link below.