Mass Turnover Time
Distinguish inventory/accumulation and inventory/loss turnover under supplied mass fluxes; neither is the dynamical terminus response time.
Description
Mass turnover divides a glacier’s inventory by a replenishment or loss flux.
Mass turnover divides a glacier’s inventory by a replenishment or loss flux. Accumulation and loss turnover can differ when the glacier is out of balance.1
Distinguish inventory/accumulation and inventory/loss turnover under supplied mass fluxes; neither is the dynamical terminus response time.
When to use Mass Turnover Time
Use this for the following task: Distinguish inventory/accumulation and inventory/loss turnover under supplied mass fluxes; neither is the dynamical terminus response time.
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 Mass Turnover Time 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 iceMassKg, annualAccumulationKg, annualAblationAndDischargeKg using the field table, then run the tool.
- Read accumulationTurnoverYears, lossTurnoverYears, netMassChangeKgPerYear. 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 |
|---|---|---|---|
| iceMassKg | Ice mass kg | number | Required |
| annualAccumulationKg | Annual accumulation kg | number | Required |
| annualAblationAndDischargeKg | Annual ablation and discharge kg | number | Required |
Require positive inventory and both annual fluxes. Return the two timescales and signed accumulation minus loss.2
accumulation time = mass/accumulation; loss time = mass/loss This summarizes the declared operation. Units, indexing, inclusivity and exceptional cases are explained in the surrounding text.
| Output field | Meaning | Value type |
|---|---|---|
| accumulationTurnoverYears | Accumulation turnover years | number |
| lossTurnoverYears | Loss turnover years | number |
| netMassChangeKgPerYear | Net mass change kg per year | number |
{
"input": {
"iceMassKg": 1000,
"annualAccumulationKg": 100,
"annualAblationAndDischargeKg": 125
},
"output": {
"accumulationTurnoverYears": 10,
"lossTurnoverYears": 8,
"netMassChangeKgPerYear": -25
}
}Limitations and assumptions
Turnover is not the dynamical terminus response time; fluxes are treated as constant.
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 Glacier Response Time Johannesson for this operation: Use Johannesson thickness/terminus-ablation response time with a linear exponential length-anomaly relaxation; no geometry-dependent higher-order response is inferred. For a complementary task, use Residual Flux Mass Balance Checker for this operation: Audit a bounded glacier mass-control-volume budget against independent observed storage change; residual sign is observed minus predicted and missing processes are not diagnosed.
Further background: Glacier accumulation, ablation and mass balance.
References
-
Mass Turnover Time — tool.io
Similar or alternative tools
- Glacier Response Time Johannesson
Use Johannesson thickness/terminus-ablation response time with a linear exponential length-anomaly relaxation; no geometry-dependent higher-order response is inferred.
- Residual Flux Mass Balance Checker
Audit a bounded glacier mass-control-volume budget against independent observed storage change; residual sign is observed minus predicted and missing processes are not diagnosed.