Lake Evaporation Energy Balance Method
Estimate signed evaporation by a caller Bowen-ratio available-energy budget including storage/advected heat; negative results indicate condensation-model potential and missing fluxes are not diagnosed.
Description
An energy budget partitions available lake heat between sensible and latent heat fluxes.
An energy budget partitions available lake heat between sensible and latent heat fluxes. A supplied Bowen ratio relates those two fluxes, allowing signed evaporation to be estimated.1
The tool returns signedLatentHeatFluxWattsPerM2, signedEvaporationMmPerDay. The computation uses supplied observations and parameters rather than acquiring measurements.
When to use Lake Evaporation Energy Balance Method
Use this for the following task: Estimate signed evaporation by a caller Bowen-ratio available-energy budget including storage/advected heat; negative results indicate condensation-model potential and missing fluxes are not diagnosed. Prepare observations and calibration parameters on the same unit and reporting basis.
How to use Lake Evaporation Energy Balance Method and understand its results
- Prepare the measured quantities and supplied model parameters. Match the units and align paired lists before calculating.
- Enter netRadiationWattsPerM2, storageHeatGainWattsPerM2, netAdvectedHeatWattsPerM2, bowenRatio, waterDensityKgPerM3, latentHeatJPerKg, secondsPerDay according to the field table, then run the tool.
- Read signedLatentHeatFluxWattsPerM2, signedEvaporationMmPerDay. 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 |
|---|---|---|---|
| netRadiationWattsPerM2 | Net radiation watts per m2 | number | Required |
| storageHeatGainWattsPerM2 | Storage heat gain watts per m2 | number | Required |
| netAdvectedHeatWattsPerM2 | Net advected heat watts per m2 | number | Required |
| bowenRatio | Bowen ratio | number | Required |
| waterDensityKgPerM3 | Water density kg per m3 | number | Required |
| latentHeatJPerKg | Latent heat j per kg | number | Required |
| secondsPerDay | Seconds per day | number | Required |
Use signed heat fluxes, a Bowen ratio greater than −1 and positive density, latent heat and day length. Return latent flux and signed evaporation.
latentFlux=(netRadiation−storageHeatGain+netAdvectedHeat)/(1+BowenRatio); mm/day=1000×latentFlux×secondsPerDay/(density×latentHeat) The symbols and boundary conditions refer to the supplied fields and the implementation described above.
| Output field | Meaning | Value type |
|---|---|---|
| signedLatentHeatFluxWattsPerM2 | Signed latent heat flux watts per m2 | number |
| signedEvaporationMmPerDay | Signed evaporation mm per day | number |
{
"input": {
"netRadiationWattsPerM2": 100,
"storageHeatGainWattsPerM2": 20,
"netAdvectedHeatWattsPerM2": 10,
"bowenRatio": 0.5,
"waterDensityKgPerM3": 1000,
"latentHeatJPerKg": 2400000,
"secondsPerDay": 86400
},
"output": {
"signedLatentHeatFluxWattsPerM2": 60,
"signedEvaporationMmPerDay": 2.16
}
}Limitations and assumptions
Negative values represent condensation potential in this supplied model. Missing heat fluxes, changing lake storage and an inappropriate Bowen ratio are not diagnosed.
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 Evaporation Pan To Lake Coefficient when you need its operation: Infer a pan-to-lake coefficient from a matched fixed-area observed lake water budget; negative inferred evaporation/coefficient exposes condensation or missing fluxes rather than being forced to an empirical default. Choose Heat Content Per Area for the complementary operation: Compute lake sensible heat relative to caller temperature from layer volumes and constant supplied density/heat capacity; reference changes alter absolute content, not heat differences.
Background reference: Evaporation from the Interior of Lake Okeechobee, 2013–16.
References
-
Evaporation from the Interior of Lake Okeechobee, 2013–16 — Shoemaker and Wu, U.S. Geological Survey
Similar or alternative tools
- Evaporation Pan To Lake Coefficient
Infer a pan-to-lake coefficient from a matched fixed-area observed lake water budget; negative inferred evaporation/coefficient exposes condensation or missing fluxes rather than being forced to an empirical default.
- Heat Content Per Area
Compute lake sensible heat relative to caller temperature from layer volumes and constant supplied density/heat capacity; reference changes alter absolute content, not heat differences.