Close Off Age Lock In Depth Calculator
Estimate ice residence ages at supplied lock-in/close-off depths from layered mass and steady accumulation; not gas age, gas-ice age difference, densification kinetics or automatically locating close-off.
Description
Layer mass and steady accumulation can estimate ice residence age at supplied firn depths.
Layer mass and steady accumulation can estimate ice residence age at supplied firn depths. Ice age differs from trapped-gas age.1
Enter depth boundaries starting 0 and strictly increasing, one fewer positive layer densities≤positive ice density, positive ice-equivalent accumulation and ordered lock-in/close-off depths inside column. Integrate partial layers; return two ages and difference.
When to use Close Off Age Lock In Depth Calculator
Use Close Off Age Lock In Depth Calculator when you need to evaluate the supplied records under the calculation and evidence rules below. No gas age, gas–ice age difference, densification kinetics or automatic depth detection is inferred.
Prepare the observed ice, snow, water or geometry measurements and explicit calibration parameters requested. Keep coordinates, datum, density and time units consistent.
How to use Close Off Age Lock In Depth Calculator and understand its results
- Prepare the observed ice, snow, water or geometry measurements and explicit calibration parameters requested. Keep coordinates, datum, density and time units consistent.
- Enter layerBoundaryDepthsM, layerDensitiesKgM3, iceDensityKgM3, iceEquivalentAccumulationMYear, lockInDepthM, closeOffDepthM using the field table and calculation rules, then run the tool.
- Read modeledLockInIceAgeYears, modeledCloseOffIceAgeYears, modeledAgeBetweenLockInAndCloseOffYears. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| layerBoundaryDepthsM | Layer boundary depths m | list of number | Required |
| layerDensitiesKgM3 | Layer densities kg m3 | list of number | Required |
| iceDensityKgM3 | Ice density kg m3 | number | Required |
| iceEquivalentAccumulationMYear | Ice equivalent accumulation m year | number | Required |
| lockInDepthM | Lock in depth m | number | Required |
| closeOffDepthM | Close off depth m | number | Required |
Enter depth boundaries starting 0 and strictly increasing, one fewer positive layer densities≤positive ice density, positive ice-equivalent accumulation and ordered lock-in/close-off depths inside column. Integrate partial layers; return two ages and difference.
age(depth)=sum(coveredLayerThickness×layerDensity/iceDensity)/iceAccumulation Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| modeledLockInIceAgeYears | Modeled lock in ice age years | number |
| modeledCloseOffIceAgeYears | Modeled close off ice age years | number |
| modeledAgeBetweenLockInAndCloseOffYears | Modeled age between lock in and close off years | number |
{
"input": {
"layerBoundaryDepthsM": [
0,
10,
20
],
"layerDensitiesKgM3": [
500,
800
],
"iceDensityKgM3": 1000,
"iceEquivalentAccumulationMYear": 1,
"lockInDepthM": 10,
"closeOffDepthM": 20
},
"output": {
"modeledLockInIceAgeYears": 5,
"modeledCloseOffIceAgeYears": 13,
"modeledAgeBetweenLockInAndCloseOffYears": 8
}
}Limitations and assumptions
No gas age, gas–ice age difference, densification kinetics or automatic depth detection is inferred.
Numeric inputs, where present, must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Numeric lists are limited to 10,000 entries; string lists to 128 strings of at most 128 characters each. The rules above may impose smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.
Alternative or Complementary methods
Use Snow to Ice Thickness Conversion Calculator: Compaction from snow to a selected ice density can conserve layer mass. Ice-equivalent thickness differs from water-equivalent thickness. For a complementary task, use Vertical Velocity From Accumulation Calculator: An ideal steady ice column can use a linear vertical-velocity profile. The declared convention takes upward velocity as positive.
References
-
Close Off Age Lock In Depth Calculator — tool.io
Similar or alternative tools
- Snow to Ice Thickness Conversion Calculator
Compaction from snow to a selected ice density can conserve layer mass. Ice-equivalent thickness differs from water-equivalent thickness.
- Vertical Velocity From Accumulation Calculator
An ideal steady ice column can use a linear vertical-velocity profile. The declared convention takes upward velocity as positive.