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Depth Alignment

This page documents how EN4 / ARGO temperature profiles are projected onto the GLORYS depth grid.

Use Data Sources for native product properties and Production Dataset for the spatial and temporal assembly pipeline.

Native Vertical Coordinates

  • GLORYS uses one fixed, monotonic 50-level depth coordinate.
  • EN4 / ARGO stores profile samples at profile-specific DEPH_CORRECTED depths.
  • EN4 profile arrays may have up to 400 storage slots, but those slots are not a shared physical depth axis.

Target Grid

  • The raw dataset uses the full 50 GLORYS depth levels as the target channel axis.
  • Depth alignment is applied profile-by-profile before spatial rasterization.
  • x, y, x_valid_mask, and y_valid_mask therefore share the same GLORYS-aligned depth layout.

Per-Profile Alignment Procedure

  1. Read finite (DEPH_CORRECTED, POTM_CORRECTED) pairs from one EN4 / ARGO profile. TEMP remains available only for explicitly requested legacy in-situ exports.
  2. Sort the samples by depth and collapse duplicate depths.
  3. For each GLORYS target depth inside the observed profile range, linearly interpolate temperature.
  4. Accept the interpolated value only when the nearest observed ARGO depth satisfies abs(nearest_depth - target_depth) <= max(0.1 * target_depth, 10 m).
  5. Leave out-of-range or rejected targets invalid; no depth extrapolation is applied.

Output Semantics

  • During GeoTIFF export, ARGO is resampled onto the GLORYS depth axis before patch rasterization.
  • x_valid_mask marks aligned Argo depths that passed the profile-range and nearest-depth checks.
  • The model-facing x, y, x_valid_mask, and y_valid_mask tensors share this GLORYS depth axis.

Diagnostics

The contributor plotting CLIs can inspect corrected-depth distributions, ARGO-to-GLORYS channel mapping, and target-alignment shifts directly from a selected dataset. Invoke the plot_argo_corrected_depth_*, plot_argo_glorys_depth_mapping, or plot_glorys_target_alignment_shift modules listed in the CLI reference. Generated figures and reports are run artifacts, not part of the saved dataset contract.