Modeled tritium in the ocean due to accidental and ALPS-treated water release from the Fukushima Daiichi Nuclear Power Plant site

This data set contains modeled tritium concentrations in the ocean due to accidental and ALPS-treated water release from the Fukushima Daiichi Nuclear Power Plant site. A complete description can be found in Cauquoin, A., Gusyev, M., Komuro, Y., Ono, J., and Yoshimura, K. Ocean general circulation model simulations of anthropogenic tritium releases from the Fukushima Daiichi Nuclear Power Plant site, Mar. Pollut. Bull., 220, 118294, doi:10.1016/j.marpolbul.2025.118294, 2025. The details of the simulations, performed with the ocean general circulation model COCO4.9, are summarized in the table below: Simulation name Release Duration 3H input Forcing Horiz. grid. res. Variables ALPS_ref_2011-2019 ALPS-treated water 9 years TEPCO scenario A repeating 01/2011–12/2019 period 360 x 256 monmean.3H.mean_13m.remap1deg accident_min accidental —"— Machida et al. min. inventory —"— —"— monmean.3H.mean_13m.remap1deg accident_max —"— —"— Machida et al. max. inventory —"— —"— monmean.3H.mean_13m.remap1deg ALPS_ref_1980-1999 ALPS-treated water 77 years TEPCO scenario A repeating 01/1980–12/1999 period 360 x 256 monmean.3H.mean_13m.360x256, monmean.3H.remap1deg, monmean.uo.lev11.remap1deg, monmean.vo.lev11.remap1deg, timmean.sst.remap1deg ALPS_SSP5-8.5 —"— —"— —"— SSP5-8.5 scenario (MIROC6) —"— monmean.3H.mean_13m.360x256, monmean.3H.remap1deg, monmean.uo.lev11.remap1deg, monmean.vo.lev11.remap1deg, timmean_202301-205012.sst.remap1deg, timmean_205101-209912.sst.remap1deg ALPS_highres —"— —"— —"— repeating 01/1980–12/1999 period 1440 x 1280 monmean.3H.mean_13m.1440x1280, monmean.3H.remap1deg, monmean.uo.lev11.remap1deg, monmean.vo.lev11.remap1deg The variables are: monmean.3H.mean_13m.remap1deg: monthly tritium concentrations in surface seawater (i.e., in the first 13 m) in Bq/L, remapped at 1° horizontal resolution. monmean.3H.mean_13m.360x256: monthly tritium concentrations in surface seawater (i.e., in the first 13 m) in Bq/L on the raw horizontal grid 360x256. monmean.3H.mean_13m.1440x1280: monthly tritium concentrations in surface seawater (i.e., in the first 13 m) in Bq/L on the raw horizontal grid 1440x1280. monmean.3H.remap1deg: monthly tritium concentrations in the ocean (in all depth layers) in Bq/L, remapped at 1° horizontal resolution. monmean.uo.lev11.remap1deg: ocean zonal velocity at 11 m deep in cm/s, remapped at 1° horizontal resolution. monmean.vo.lev11.remap1deg: ocean meridional velocity at 11 m deep in cm/s, remapped at 1° horizontal resolution. timmean.sst.remap1deg: present-day mean sea surface temperature in °C, remapped at 1° horizontal resolution. timmean_202301-205012.sst.remap1deg: projected mean sea surface temperature (°C) for the period 2023-2050 under SSP5-8.5 scenario, remapped at 1° horizontal resolution. timmean_205101-209912.sst.remap1deg: projected mean sea surface temperature (°C) for the period 2051-2099 under SSP5-8.5 scenario, remapped at 1° horizontal resolution. There is one zip file per simulation. Each zip file contains netcdf files of the modeled outputs detailed in the column "Variables" of the table above. For the ALPS_ref_2011-2019, accident_min, and accident_max simulations, values for the period 2011-2019 are provided. For the ALPS_ref_1980-1999, ALPS_SSP5-8.5, and ALPS_highres simulations, values for the period 2023-2099 are provided. In addition, the tritium activity flux values for the accidental discharge and the ALPS_treated water release used as inputs to COCO4.9 are provided in the excel file tritium_activity_input_FDNPP.xlsx. The production of this dataset was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI Grant 22K20379 and the Environmental Radioactivity Network Center (ERAN) FY2025 Collaborative Researcher Grant P-25-22.