Temperature-Salinity Diagram

What This Page Does

This page plots temperature-salinity (T–S) relationships for filtered reference data and optional browser-uploaded data. It includes approximate σ0 reference contours and a sampling-location map when coordinates are available.

Basic Workflow

1. Select reference data and set the sidebar filters.
2. Optionally upload a CSV, XLSX, or XLS file, then assign its temperature and salinity columns. Longitude and latitude are also needed for the location map.
3. Select Show background data, a colour parameter, and other display options.
4. Select Apply settings to update the figure.
5. Adjust axes, the colour bar, and the σ0 reference-contour interval as needed.
6. Inspect the plotted data and download a PNG figure when needed.

Main Controls

• Show background data
• Show legend
• Color parameter
• Colorbar range
• Salinity scale
• Temperature scale
• Density contour interval (approx. σ0) — spacing between approximate σ0 reference contour lines (0.2, 0.5, or 1.0 kg m⁻³; default 0.5 kg m⁻³)
• Figure width / height
• Tick font size / Label font size
• X tick count / Y tick count
• Map controls / Map style
• Uploaded data quality — reports usable rows and missing required values for the current browser upload.

Outputs

• Temperature-Salinity diagram
• Density contours
• Sampling location map, when valid longitude and latitude are available
• Downloadable PNG figure
• Filtered dataset table

Notes And Limitations

• Density contours require valid salinity and temperature values.
• Missing values are excluded from the plotted points and reported in captions.
• Browser uploads exist only for the current browser session. They do not alter a reference dataset or persistent User Excel data.
• The density contours are approximate σ0 reference contours, not pointwise sample density. They pass Practical Salinity (≈ Absolute Salinity) and in-situ temperature (≈ Conservative Temperature) directly to gsw.sigma0; the application does not convert each observation to Absolute Salinity and Conservative Temperature using its location and pressure. Differences from fully converted TEOS-10 values vary by data source, location, depth, and hydrographic conditions. Use the contour lines as visual reference guides, not as true TEOS-10 density values or a basis for quantitative water-mass classification.
• The contour grid is bounded by the selected display-axis range and clipped to the quality-checked input domain (Salinity 0–50; Temperature −5–45 °C), so negative salinity values selected on the axis are not passed to the density calculation.