Freeboard Flotation Requirement

Infer freely floating thickness and draft from measured freeboard with explicit firn-air correction; unsupported if grounded, flexing or under external loads.

Description

Floating ice freeboard depends on density contrast and air trapped in firn.

Floating ice freeboard depends on density contrast and air trapped in firn. Hydrostatic balance can infer thickness only when the floating assumptions apply.

Infer freely floating thickness and draft from measured freeboard with explicit firn-air correction; unsupported if grounded, flexing or under external loads.

When to use Freeboard Flotation Requirement

Use this for the following task: Infer freely floating thickness and draft from measured freeboard with explicit firn-air correction; unsupported if grounded, flexing or under external loads.

Prepare the measurements and calibration parameters in the declared units. Keep vector entries aligned and choose a consistent spatial frame and time basis.

How to use Freeboard Flotation Requirement and understand its results

Prepare the measurements and calibration parameters in the declared units. Keep vector entries aligned and choose a consistent spatial frame and time basis.
Enter measuredFreeboardM, firnAirEquivalentThicknessM, iceDensityKgPerM3, waterDensityKgPerM3 using the field table, then run the tool.
Read inferredFloatingThicknessM, inferredDraftM. Interpret flags, units, ordering and placeholder values using the rules below.
Review any reported issue or failed check, correct the supplied values when appropriate, and verify the result in its intended context.

Input field	Meaning	Value type and bounds	Requirement
measuredFreeboardM	Measured freeboard m	number	Required
firnAirEquivalentThicknessM	Firn air equivalent thickness m	number	Required
iceDensityKgPerM3	Ice density kg per m3	number	Required
waterDensityKgPerM3	Water density kg per m3	number	Required

Require water density greater than ice density and nonnegative freeboard/firn air. Reject negative inferred thickness/draft or firn air exceeding the total thickness.^[1]

H = (ρwater freeboard − ρice firnAirThickness)/(ρwater−ρice); draft = H−freeboard

This summarizes the declared operation. Units, indexing, inclusivity and exceptional cases are explained in the surrounding text.

Output field	Meaning	Value type
inferredFloatingThicknessM	Inferred floating thickness m	number
inferredDraftM	Inferred draft m	number

json

{
  "input": {
    "measuredFreeboardM": 20,
    "firnAirEquivalentThicknessM": 0,
    "iceDensityKgPerM3": 900,
    "waterDensityKgPerM3": 1000
  },
  "output": {
    "inferredFloatingThicknessM": 200,
    "inferredDraftM": 180
  }
}

Limitations and assumptions

Grounded, flexing or externally loaded ice can violate hydrostatic assumptions. This does not establish that the ice is afloat.

Constants and empirical coefficients are supplied rather than calibrated. Check units and observational applicability before interpreting the model. Malformed requests produce input errors. A successfully evaluated request can still contain false flags, empty result lists or a result outside the supplied threshold; those outcomes have the meanings stated above.

Alternative or Complementary methods

Choose Firn Air Content Percentage for this operation: Integrate air volume fraction 1−rho/rho_ice through layered firn; assumes pore space is air and excludes liquid water and pressure-compressed gas. For a complementary task, use Ice Volume to Sea Level Rise for this operation: Estimate grounded-ice sea-level equivalent after filling released sub-sea-level bed cavities; excludes floating ice, seawater salinity dilution, ocean area changes and gravitational fingerprints.

The implementation reference documents the exact calculation, supported input shapes and returned fields.

References

Freeboard Flotation Requirement — tool.io

Similar or alternative tools

Firn Air Content Percentage
Integrate air volume fraction 1−rho/rho_ice through layered firn; assumes pore space is air and excludes liquid water and pressure-compressed gas.
Ice Volume to Sea Level Rise
Estimate grounded-ice sea-level equivalent after filling released sub-sea-level bed cavities; excludes floating ice, seawater salinity dilution, ocean area changes and gravitational fingerprints.