README.md

---
license: other
pretty_name: DepthDif GeoTIFF raster and aligned ARGO dataset
tags:
- oceanography
- argo
- glorys
- ostia
- sea-level
- sea-surface-salinity
- geotiff
- zarr
configs:
- config_name: profile-index
  data_files:
  - split: profiles
    path: indices/profiles.parquet
  - split: variables
    path: indices/variables.parquet
---

# DepthDif GeoTIFF Raster and Aligned ARGO Dataset

This dataset package contains the model-ready DepthDif GeoTIFF raster store and
the enriched ARGO profile Zarr used to create it.

## Dataset Overview

<p align="center">
  <img src="assets/figures/depthdif_schema.png" width="85%" alt="DepthDif dataset and model overview" />
</p>

## Layout

```text
assets/
  figures/depthdif_schema.png
  data/geotiff_dataset_random100_surface.png
  data/argo_on_glorys_grid_3D.gif
  data/profile_comparison_good_alignment.png
  data/profile_comparison_bad_alignment.png
rasters/
  glorys/thetao/
  glorys/so/
  ostia/analysed_sst/
  sealevel/adt/
  sss/sos/
  sss/dos/
argo/
  argo_profiles_on_grid.zarr/
data/
  argo_glors_ostia_ssh.zarr/
indices/
  profiles.parquet
  variables.parquet
metadata/
  dataset_description.json
  citation.cff
  stac-item.json
examples/
  open_with_xarray.py
  subset_by_region_time.py
manifest.yaml
masks/
```

The `rasters/` directory is intentionally at the repository root. It contains
the aligned uint8 GeoTIFF products used by the pixel-space dataloader. The
compact `argo/argo_profiles_on_grid.zarr` store is the grid-indexed ARGO input
used by that dataloader.

The package intentionally contains two ARGO Zarr stores with different roles.
`argo/argo_profiles_on_grid.zarr` is the compact grid-indexed store meant to be
used together with the GeoTIFF raster dataset. `data/argo_glors_ostia_ssh.zarr`
is the full enriched profile-level store and holds the complete ARGO
collocation dataset, including the sampled GLORYS, OSTIA, sea-level, and
sea-surface-salinity context.

## Raster Example

Representative surface-level training patches from the exported GeoTIFF store:

<p align="center">
  <img src="assets/data/geotiff_dataset_random100_surface.png" width="85%" alt="Random surface-level training dataset patches" />
</p>

## Raster Products

All GeoTIFF rasters are exported on the GLORYS 0.1 degree global grid
(`EPSG:4326`, 3600 x 1800 pixels, west-to-east longitudes from -180 to 180 and
north-to-south latitudes from 90 to -90). The current package contains 761
weekly target dates per raster product, from 2010-01-01 through 2024-07-26.
Files are named `<variable>_YYYYMMDD.tif`.

The GLORYS variables are depth-resolved 50-band GeoTIFFs:

- `rasters/glorys/thetao/`: potential temperature, encoded as Kelvin.
- `rasters/glorys/so/`: salinity, encoded as PSU.

The surface products are single-band GeoTIFFs aggregated to the same weekly
target dates with a centered 7-day mean window:

- `rasters/ostia/analysed_sst/`: OSTIA analysed sea-surface temperature in Kelvin.
- `rasters/sealevel/adt/`: absolute dynamic topography in meters.
- `rasters/sss/sos/`: sea-surface salinity in PSU.
- `rasters/sss/dos/`: sea-surface density in kg/m3.

Raster pixels are stored as `uint8` with `255` reserved for nodata. Valid codes
`0..254` are linearly decoded using the stretch ranges in `manifest.yaml`;
per-file statistics, source filenames, compression, target dates, and the full
depth axis are also recorded there.

## ARGO Alignment Examples

ARGO profiles are projected onto the fixed 50-level GLORYS depth axis before
spatial rasterization. The examples below show the grid-indexed ARGO
representation and profile-level alignment quality.

<p align="center">
  <img src="assets/data/argo_on_glorys_grid_3D.gif" width="70%" alt="Depth-aligned ARGO values on the GLORYS grid" />
</p>

<p align="center">
  <img src="assets/data/profile_comparison_good_alignment.png" width="72%" alt="Example of good ARGO-to-GLORYS profile alignment" />
</p>

<p align="center">
  <img src="assets/data/profile_comparison_bad_alignment.png" width="72%" alt="Example of weaker ARGO-to-GLORYS profile alignment" />
</p>

The full enriched profile-level ARGO collocation dataset is available at:

```python
import xarray as xr

ds = xr.open_zarr("data/argo_glors_ostia_ssh.zarr", consolidated=None)
```

The lightweight Parquet indices are included for preview and filtering:

```python
import pandas as pd

profiles = pd.read_parquet("indices/profiles.parquet")
variables = pd.read_parquet("indices/variables.parquet")
```

Coverage:

- Raster target dates: 2010-01-01 to 2024-07-26
- Enriched ARGO profile dates: 2010-01-01 to 2024-07-31
- GLORYS depth levels: 50

Upstream product licenses and citation requirements for EN4/ARGO, GLORYS,
OSTIA, sea-level, and sea-surface-salinity products still apply.