Piston Velocity Gas Exchange
Scale a measured reference gas-transfer piston velocity by a supplied Schmidt-number power relation; does not infer wind dependence or gas concentration gradients.
Description
Gas-transfer piston velocity describes an effective exchange speed across the water surface.
Gas-transfer piston velocity describes an effective exchange speed across the water surface. A Schmidt-number scaling transfers a measured reference velocity to another gas or condition.1
The tool returns scaledPistonVelocityMPerDay. The computation uses supplied observations and parameters rather than acquiring measurements.
When to use Piston Velocity Gas Exchange
Use this for the following task: Scale a measured reference gas-transfer piston velocity by a supplied Schmidt-number power relation; does not infer wind dependence or gas concentration gradients. Prepare observations and calibration parameters on the same unit and reporting basis.
How to use Piston Velocity Gas Exchange and understand its results
- Prepare the measured quantities and supplied model parameters. Match the units and align paired lists before calculating.
- Enter referencePistonVelocityMPerDay, gasSchmidtNumber, referenceSchmidtNumber, schmidtExponent according to the field table, then run the tool.
- Read scaledPistonVelocityMPerDay. 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 |
|---|---|---|---|
| referencePistonVelocityMPerDay | Reference piston velocity m per day | number | Required |
| gasSchmidtNumber | Gas schmidt number | number | Required |
| referenceSchmidtNumber | Reference schmidt number | number | Required |
| schmidtExponent | Schmidt exponent | number | Required |
Supply nonnegative reference velocity and positive gas Schmidt number, reference Schmidt number and exponent. Evaluate the scaling in metres per day.
k=referenceVelocity×(gasSchmidt/referenceSchmidt)^(−exponent) The symbols and boundary conditions refer to the supplied fields and the implementation described above.
| Output field | Meaning | Value type |
|---|---|---|
| scaledPistonVelocityMPerDay | Scaled piston velocity m per day | number |
{
"input": {
"referencePistonVelocityMPerDay": 2,
"gasSchmidtNumber": 600,
"referenceSchmidtNumber": 600,
"schmidtExponent": 0.5
},
"output": {
"scaledPistonVelocityMPerDay": 2
}
}Limitations and assumptions
The reference velocity and exponent must already be appropriate. No wind dependence, concentration gradient or resulting gas flux is inferred.
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 CO2 Flux Atmosphere Lake when you need its operation: Combine a caller Henry equilibrium with measured dissolved CO2 and piston velocity into signed atmosphere–lake flux; positive is emission, negative uptake, and carbonate speciation is external. Choose Methane Bubbling Emission Estimate for the complementary operation: Normalize trap-measured bubble methane by dry-gas ideal-law correction and summed area×time; negative blank-corrected estimates are preserved as nondetection evidence, not clamped emissions.
Background reference: Estimating lake-atmosphere CO2 exchange.
References
-
Estimating lake-atmosphere CO2 exchange — U.S. Geological Survey
Similar or alternative tools
- CO2 Flux Atmosphere Lake
Combine a caller Henry equilibrium with measured dissolved CO2 and piston velocity into signed atmosphere–lake flux; positive is emission, negative uptake, and carbonate speciation is external.
- Methane Bubbling Emission Estimate
Normalize trap-measured bubble methane by dry-gas ideal-law correction and summed area×time; negative blank-corrected estimates are preserved as nondetection evidence, not clamped emissions.