# Bias-corrected Ocean Temperature, Salinity, and Sea-Ice Concentration Datasets for Present, Non-Warming, and Future Climates

## Overview

This repository provides metadata and access information for bias-corrected datasets of ocean temperature, salinity, and sea-ice concentration developed for historical, non-warming, and future climate conditions.

The datasets are designed to support climate change impact assessment, climate model experiments, and ocean data assimilation.

## Data Access

The datasets are archived and distributed through the Meteorological Research Institute data server:

https://climate.mri-jma.go.jp/pub/archives/Ushijima-et-al_Upper_Ocean_Data

## Directory Structure

```text
Ushijima-et-al_Upper_Ocean_Data
│
├── PAST
│
├── NW
│
├── SSP126
│   ├── <CMIP6 model>_v00
│   ├── <CMIP6 model>_v10
│   ├── <CMIP6 model>_v20
│   ├── <CMIP6 model>_v30
│   ├── <CMIP6 model>_v40
│   ├── <CMIP6 model>_v50
│   └── <CMIP6 model>_v60
│
├── SSP245
│   └── ...
│
└── SSP585
    └── ...
```

The `PAST` directory contains climate data from 1850 to 2020.

For 1961–2020, observed estimates of internal variability are used (Mizuta et al., 2026). For the spin-up period (1850–1960), internal variability is generated by repeatedly applying the variability estimated from 1961–2020. Consequently, the internal variability before 1961 does not represent the actual historical evolution.

The `NW` directory contains non-warming climate data.

The `SSP126`, `SSP245`, and `SSP585` directories contain future climate data under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios, respectively.

Within each SSP directory, dataset directories are named as `<CMIP6 model>_vXX`, where `v00`, `v10`, `v20`, `v30`, `v40`, `v50`, and `v60` denote different phases of internal variability. These correspond to transition years of internal variability in 1961, 1971, 1981, 1991, 2001, and 2011, respectively, which are aligned to model year 2021.

## File Contents

Each dataset directory contains the following files.

- **Ocean temperature and salinity**
  - `ProjD-7.5_1x1_YYYY.grb2`

- **Sea-ice concentration**
  - `cobe-sic2_1x1_YYYY.grb2`

- **SST perturbation**
  - `cobe-sst2_ptb_1x1_YYYY.grb2`

- **SIC perturbation**
  - `cobe-sic2_ptb_1x1_YYYY.grb2`

`YYYY` denotes the year.

All datasets are provided in GRIB2 format. A corresponding GrADS control file (`.ctl`) is also provided for each GRIB2 file.

## Additional Information

Detailed information on the methodology, validation, experimental design, and limitations of the datasets is provided in the associated *Scientific Data* publication (Ushijima et al., submitted).

## License

This dataset is distributed under the Creative Commons Attribution 4.0 International (CC BY 4.0) License.

## Citation

When using these datasets, please cite both the dataset DOI and the associated *Scientific Data* publication (Ushijima et al., submitted).

## References

Mizuta, R., Endo, H., Kawai, H., *et al.* Climate simulations using MRI-ESM2 with 60 km resolution atmosphere and data assimilated ocean. *J. Meteorol. Soc. Jpn.* 104, 10 (2026). https://doi.org/10.1007/s44394-025-00011-2

Ushijima, Y., Tsujino, H., Mizuta, R., *et al.* Bias-corrected upper-ocean data for impact assessments of global warming and assimilation into climate models. *Sci Data*. (submitted)