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.

Description

Sensible heat content depends on water volume, temperature and a chosen reference temperature.

Sensible heat content depends on water volume, temperature and a chosen reference temperature. Dividing total heat by surface area enables comparison on an areal basis.^[1]

The tool returns signedHeatContentJ, heatContentPerSurfaceAreaJPerM2. The computation uses supplied observations and parameters rather than acquiring measurements.

When to use Heat Content Per Area

Use this for the following task: 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. Prepare observations and calibration parameters on the same unit and reporting basis.

How to use Heat Content Per Area and understand its results

Prepare the measured quantities and supplied model parameters. Match the units and align paired lists before calculating.
Enter depthBoundariesM, layerAreasM2, layerTemperaturesC, referenceTemperatureC, waterDensityKgPerM3, specificHeatJPerKgK according to the field table, then run the tool.
Read signedHeatContentJ, heatContentPerSurfaceAreaJPerM2. 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
depthBoundariesM	Depth boundaries m	list of number	Required
layerAreasM2	Layer areas m2	list of number	Required
layerTemperaturesC	Layer temperatures c	list of number	Required
referenceTemperatureC	Reference temperature c	number	Required
waterDensityKgPerM3	Water density kg per m3	number	Required
specificHeatJPerKgK	Specific heat j per kg k	number	Required

Supply boundaries starting at zero, positive constant layer areas, aligned temperatures, and positive density and specific heat. Compute each layer volume and sum signed heat relative to the reference.

heat=waterDensity×specificHeat×ΣlayerVolume×(temperature−reference); arealHeat=heat/surfaceArea

The symbols and boundary conditions refer to the supplied fields and the implementation described above.

Output field	Meaning	Value type
signedHeatContentJ	Signed heat content j	number
heatContentPerSurfaceAreaJPerM2	Heat content per surface area j per m2	number

json

{
  "input": {
    "depthBoundariesM": [
      0,
      1,
      2
    ],
    "layerAreasM2": [
      100,
      50
    ],
    "layerTemperaturesC": [
      10,
      5
    ],
    "referenceTemperatureC": 0,
    "waterDensityKgPerM3": 1000,
    "specificHeatJPerKgK": 4000
  },
  "output": {
    "signedHeatContentJ": 5000000000,
    "heatContentPerSurfaceAreaJPerM2": 50000000
  }
}

Limitations and assumptions

Density and heat capacity are supplied constants. Changing the reference changes absolute heat content; negative values are retained and latent heat is excluded.

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 Schmidt Stability Index when you need its operation: Compute signed Schmidt potential-energy stability from piecewise-constant layer areas/densities and depth-positive-down centers; negative values indicate an inverted profile, not positive mixing energy. Choose Lake Evaporation Energy Balance Method for the complementary operation: 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.

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

Schmidt Stability Index
Compute signed Schmidt potential-energy stability from piecewise-constant layer areas/densities and depth-positive-down centers; negative values indicate an inverted profile, not positive mixing energy.
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.