Compensation Depth Light Level
Invert constant optical extinction for a supplied compensation light threshold; a deeper-than-bottom model value is flagged, not silently clipped or declared biologically valid.
Description
A compensation light level is a caller-supplied threshold for balancing a chosen biological process.
A compensation light level is a caller-supplied threshold for balancing a chosen biological process. Constant Beer–Lambert extinction gives the depth where irradiance reaches that level.1
The tool returns modelCompensationDepthM, withinObservedWaterColumn. The computation uses supplied observations and parameters rather than acquiring measurements.
When to use Compensation Depth Light Level
Use this for the following task: Invert constant optical extinction for a supplied compensation light threshold; a deeper-than-bottom model value is flagged, not silently clipped or declared biologically valid. Prepare observations and calibration parameters on the same unit and reporting basis.
How to use Compensation Depth Light Level and understand its results
- Prepare the measured quantities and supplied model parameters. Match the units and align paired lists before calculating.
- Enter surfaceIrradiance, compensationIrradiance, extinctionCoefficientPerMeter, maximumObservedDepthM according to the field table, then run the tool.
- Read modelCompensationDepthM, withinObservedWaterColumn. Use the calculation below to interpret the selected mean or the model’s signs, units and comparison flags.
- Review the supplied assumptions and calibration before comparing or reporting the result.
| Input field | Meaning | Value type and bounds | Requirement |
|---|---|---|---|
| surfaceIrradiance | Surface irradiance | number | Required |
| compensationIrradiance | Compensation irradiance | number | Required |
| extinctionCoefficientPerMeter | Extinction coefficient per meter | number | Required |
| maximumObservedDepthM | Maximum observed depth m | number | Required |
Use positive irradiances and extinction coefficient, with compensation no greater than surface light and a nonnegative maximum observed depth. Return the model depth and an inclusive within-column flag.
depth=ln(surfaceIrradiance/compensationIrradiance)/extinctionCoefficient The symbols and boundary conditions refer to the supplied fields and the implementation described above.
| Output field | Meaning | Value type |
|---|---|---|
| modelCompensationDepthM | Model compensation depth m | number |
| withinObservedWaterColumn | Within observed water column | boolean |
{
"input": {
"surfaceIrradiance": 100,
"compensationIrradiance": 1,
"extinctionCoefficientPerMeter": 0.5,
"maximumObservedDepthM": 5
},
"output": {
"modelCompensationDepthM": 9.210340371976184,
"withinObservedWaterColumn": false
}
}Limitations and assumptions
Deeper-than-bottom results are flagged and retained. The tool does not choose a biological threshold or fit optical extinction; coefficients are constant with depth.
Numerical inputs must be finite. Input-shape and calculation checks do not establish measurement quality or the validity of a supplied calibration.
Alternative or Complementary methods
Choose Light Attenuation Vertical Profile when you need its operation: Propagate downwelling irradiance through layered Beer–Lambert extinction; supplied coefficients include only modeled optical attenuation and no bottom reflection. Choose Littoral Zone Percent Area for the complementary operation: Classify measured lake-bottom patches by a caller colonization depth and sum area; assumes each representative depth describes its patch and does not infer vegetation presence or map geometry.
Background reference: Quantitative Spectrophotometry and Beer’s Law.
References
-
Quantitative Spectrophotometry and Beer’s Law — University of California Davis, Chemistry LibreTexts
Similar or alternative tools
- Light Attenuation Vertical Profile
Propagate downwelling irradiance through layered Beer–Lambert extinction; supplied coefficients include only modeled optical attenuation and no bottom reflection.
- Littoral Zone Percent Area
Classify measured lake-bottom patches by a caller colonization depth and sum area; assumes each representative depth describes its patch and does not infer vegetation presence or map geometry.