Core Bottom Age Extrapolation

Integrate reciprocal exponentially thinning annual-layer thickness below a reference depth; explicitly a model extrapolation, not observed core chronology or an uncertainty bound.

Description

Ice-layer thickness connects a depth increment with elapsed years.

Ice-layer thickness connects a depth increment with elapsed years. Extrapolating an exponentially thinning layer model makes age grow nonlinearly below a reference horizon.

Integrate reciprocal exponentially thinning annual-layer thickness below a reference depth; explicitly a model extrapolation, not observed core chronology or an uncertainty bound.

When to use Core Bottom Age Extrapolation

Use this for the following task: Integrate reciprocal exponentially thinning annual-layer thickness below a reference depth; explicitly a model extrapolation, not observed core chronology or an uncertainty bound.

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 Core Bottom Age Extrapolation 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 referenceDepthM, referenceAgeYears, referenceAnnualLayerThicknessM, layerThinningPerMeter, queryDepthM using the field table, then run the tool.
Read extrapolatedAgeYears. 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
referenceDepthM	Reference depth m	number	Required
referenceAgeYears	Reference age years	number	Required
referenceAnnualLayerThicknessM	Reference annual layer thickness m	number	Required
layerThinningPerMeter	Layer thinning per meter	number	Required
queryDepthM	Query depth m	number	Required

Require query depth at or below the reference, nonnegative age/depth/thinning parameters and positive reference layer thickness. Use the zero-thinning limit explicitly.^[1]

age = referenceAge + expm1(k Δdepth)/(k referenceLayerH); k=0 uses Δdepth/referenceLayerH

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

Output field	Meaning	Value type
extrapolatedAgeYears	Extrapolated age years	number

json

{
  "input": {
    "referenceDepthM": 100,
    "referenceAgeYears": 1000,
    "referenceAnnualLayerThicknessM": 0.1,
    "layerThinningPerMeter": 0.01,
    "queryDepthM": 110
  },
  "output": {
    "extrapolatedAgeYears": 1105.1709180756477
  }
}

Limitations and assumptions

The result is a model extrapolation, not observed chronology or an uncertainty bound.

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 Annual Layer Count Age At Depth for this operation: Accumulate interpreted annual-layer counts and separately supplied hiatus years at depth boundaries; ambiguous/missing annuality must be resolved externally. For a complementary task, use Ice Core Layer Thinning Depth for this operation: Propagate layer thickness through supplied vertical-strain residence intervals; negative strain thins and positive strain thickens, without inferring strain from depth.

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

References

Core Bottom Age Extrapolation — tool.io

Similar or alternative tools

Annual Layer Count Age At Depth
Accumulate interpreted annual-layer counts and separately supplied hiatus years at depth boundaries; ambiguous/missing annuality must be resolved externally.
Ice Core Layer Thinning Depth
Propagate layer thickness through supplied vertical-strain residence intervals; negative strain thins and positive strain thickens, without inferring strain from depth.