Densification Stage Herron Langway

Evaluate instantaneous Herron–Langway-form stage kinetics k(T)·accumulation^p·(rho_ice−rho), using supplied stage boundary and unit-compatible prefactors; not an integrated age-depth model.

Description

Firn densification can follow different kinetic stages separated by a density threshold.

Firn densification can follow different kinetic stages separated by a density threshold. Temperature and accumulation modify the instantaneous compaction rate.

Evaluate instantaneous Herron–Langway-form stage kinetics k(T)·accumulation^p·(rho_ice−rho), using supplied stage boundary and unit-compatible prefactors; not an integrated age-depth model.

When to use Densification Stage Herron Langway

Use this for the following task: Evaluate instantaneous Herron–Langway-form stage kinetics k(T)·accumulation^p·(rho_ice−rho), using supplied stage boundary and unit-compatible prefactors; not an integrated age-depth model.

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 Densification Stage Herron Langway 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 currentDensityKgPerM3, iceDensityKgPerM3, stageBoundaryDensityKgPerM3, accumulationMwePerYear, temperatureKelvin, gasConstantJPerMolK, stageOnePrefactor, stageTwoPrefactor, stageOneActivationJPerMol, stageTwoActivationJPerMol using the field table, then run the tool.
Read densificationStage, densityIncreaseKgPerM3Year. 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
currentDensityKgPerM3	Current density kg per m3	number	Required
iceDensityKgPerM3	Ice density kg per m3	number	Required
stageBoundaryDensityKgPerM3	Stage boundary density kg per m3	number	Required
accumulationMwePerYear	Accumulation mwe per year	number	Required
temperatureKelvin	Temperature kelvin	number	Required
gasConstantJPerMolK	Gas constant j per mol k	number	Required
stageOnePrefactor	Stage one prefactor	number	Required
stageTwoPrefactor	Stage two prefactor	number	Required
stageOneActivationJPerMol	Stage one activation j per mol	number	Required
stageTwoActivationJPerMol	Stage two activation j per mol	number	Required

Choose stage 1 below the supplied boundary and stage 2 at or above it. Require positive temperature, accumulation and prefactors, and densities below ice density. Apply the selected activation energy and power.^[1]

rate = prefactor exp(−activation/(RT)) accumulation^p (ρice−ρ); p = 1 in stage 1, 1/2 in stage 2

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

Output field	Meaning	Value type
densificationStage	Densification stage	number
densityIncreaseKgPerM3Year	Density increase kg per m3 year	number

json

{
  "input": {
    "currentDensityKgPerM3": 300,
    "iceDensityKgPerM3": 900,
    "stageBoundaryDensityKgPerM3": 550,
    "accumulationMwePerYear": 1,
    "temperatureKelvin": 250,
    "gasConstantJPerMolK": 8.314,
    "stageOnePrefactor": 0.02,
    "stageTwoPrefactor": 0.04,
    "stageOneActivationJPerMol": 0,
    "stageTwoActivationJPerMol": 0
  },
  "output": {
    "densificationStage": 1,
    "densityIncreaseKgPerM3Year": 12
  }
}

Limitations and assumptions

Prefactors must match the input units. This computes an instantaneous rate, not an integrated age/depth profile.

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 Density Depth Profile for this operation: Evaluate an explicitly calibrated exponential firn density-depth profile; distinct from stage-specific temperature/accumulation densification kinetics. For a complementary task, use 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.

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

References

Densification Stage Herron Langway — tool.io

Similar or alternative tools

Firn Density Depth Profile
Evaluate an explicitly calibrated exponential firn density-depth profile; distinct from stage-specific temperature/accumulation densification kinetics.
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.