Description
Return linear fresh/saline endmember fractions.
Aquatic concentration and exchange calculations require a defined water-volume basis and compatible time intervals. An areal inventory differs from total mass, and linear endmember fractions may lie outside physical mixture bounds. Simple volume bookkeeping does not establish real mixing, residence time or chemical transformation.
Return linear fresh/saline endmember fractions.
When to use this tool
Use Dissolved Solute Salinity Endmember Fraction when checking the stated concentration, inventory, mixture or exchange basis.
How to use the tool and how it works
- Enter observed, freshEndmember, salineEndmember. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read salineFraction, freshFraction. Use the output convention below.
Return linear fresh/saline endmember fractions. Require salineEndmember > freshEndmember; salineFraction = (observed-fresh)/(saline-fresh), freshFraction = 1-saline.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| observed | Observed | Required. Finite number. |
| freshEndmember | Fresh Endmember | Required. Finite number. |
| salineEndmember | Saline Endmember | Required. Finite number. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| salineFraction | Unclamped linear endmember fraction; values outside [0,1] are retained. | Required. Finite number. |
| freshFraction | Fresh Fraction | Required. Finite number. |
{
"input": {
"observed": 10,
"freshEndmember": 0,
"salineEndmember": 40
},
"output": {
"salineFraction": 0.25,
"freshFraction": 0.75
}
}Limitations and assumptions
- Fractions outside [0,1] are retained; compatible conservative-tracer/endmember assumptions and actual salinity observations are not verified.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use calibrated chemical measurements and a suitable complete mass-balance or transport model for actual water quality, exchange and ecological inference.
References
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