θ–S Diagram

The θ–S diagram compares potential temperature and absolute salinity for either the current search results or one float’s loaded trajectory.

Open the Diagram

Signed-in users can open Analysis → Generate θ–S (under Tools on narrower layouts). With Trajectory off, the diagram uses the current search results; with it on, it uses all cycles for the selected float. The limit is 500 profiles or cycles.

OceanGraph does not sample or split oversized inputs, so a trajectory over 500 cycles cannot be analyzed.

The latest result can be reopened without regeneration until you reset the search, leave Explore, or sign out.

With Trajectory on, θ–S can stay open alongside the time-series vertical section, and both follow the selected cycle. Only one analysis job (θ–S, Clustering, or 3D view) can run at a time.

Read the Display

• Background contours show potential density anomaly referenced to 0 dbar (σ₀). OceanGraph converts potential temperature to Conservative Temperature internally for this TEOS-10 density calculation; the plotted axes do not change.
• Each profile line uses pressure rows with a finite temperature-salinity pair. Profiles with fewer than two pairs are omitted.
• Unselected profiles use cluster colors, with excluded or unassigned profiles shown in gray. This is independent of the map’s Data layer.
• The selected profile appears in front as a thicker blue line.

Use the diagram to compare water-mass structure and mixing patterns. For a conceptual explanation, see T-S Diagrams in Oceanography Explained.