Seawater Density (simplified EOS)

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Earth & Space (astronomy, orbital mechanics, meteorology, geology, geodesy, oceanography)

Tranche

tranche-7

Evidence ID

t7-110

Ledger rows

1

No ledger note is attached.

Review findings

The atmospheric-pressure UNESCO EOS-80 polynomial tested here is standard and gives the expected values. The instrument cannot be approved as specified because it advertises optional pressure without defining the pressure-dependent equation, units, range, or whether pressure is gauge or absolute. The honest-label statement is appropriate only if the exact EOS-80 approximation, validity range, and pressure limitation are displayed.

Formula and scope findings

• The specification does not state the exact UNESCO EOS-80 density equation or its coefficients, so 'simplified linear/UNESCO-80-style polynomial' is not uniquely implementable.
• Pressure is listed as optional, but no pressure correction, pressure range, or pressure unit is specified. The atmospheric-pressure polynomial alone is not valid for nonzero pressure.
• The implementation should explicitly distinguish practical salinity S in PSU from mass-fraction salinity; PSU is dimensionless and should not be treated as g/kg without qualification.

Unit assumptions

• Temperature is in degrees Celsius on the IPTS-68/ITS-90-compatible EOS-80 temperature scale.
• Salinity is practical salinity S in PSU, numerically dimensionless, with S^(3/2) interpreted as S multiplied by sqrt(S).
• The tested polynomial computes in-situ density at zero gauge pressure, conventionally P=0 dbar; pressure-dependent density requires the UNESCO pressure correction.
• Output density is in kg/m^3.
• The atmospheric EOS-80 polynomial is intended approximately for -2 <= T <= 40 degrees C and 0 <= S <= 42 PSU; these constraints should be enforced or documented.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The negative-salinity vector produces an undefined real result and must be rejected. The convention probe also exposes a unit-label hazard: interpreting an unlabeled temperature value of 10 as Celsius versus Fahrenheit changes the expected density substantially.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "temperature_C": 0,
    "salinity_PSU": 0,
    "pressure_dbar": 0
  },
  "expected_outputs": {
    "density_kg_m3": 999.842594
  },
  "reference_data": {
    "rho_w_coefficients": {
      "a0": 999.842594,
      "a1": 0.06793952,
      "a2": -0.00909529,
      "a3": 0.0001001685,
      "a4": -0.000001120083,
      "a5": 6.536332e-9
    },
    "source_convention": "Widely tabulated standard value, UNESCO EOS-80/UNESCO Technical Papers in Marine Science 44 atmospheric pure-water density polynomial"
  },
  "working": "Use rho_w(T)=a0+a1*T+a2*T^2+a3*T^3+a4*T^4+a5*T^5. At T=0: rho_w=999.842594+0.06793952*0-0.00909529*0^2+0.0001001685*0^3-0.000001120083*0^4+0.000000006536332*0^5=999.842594 kg/m^3. At S=0, all salinity terms are zero, so rho=999.842594 kg/m^3."
}

Related workflows

No source-defined multi-instrument workflow membership is recorded.

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche7/tranche7-results.json
• BOUNDARY_HAZARD_CATALOG.json