Description
Average supplied Secchi disappearance and reappearance depths.
Aquatic measurements depend on depth datums, effective sampling area, layer weights and concentration definitions. Secchi pair averages differ from a full optical model, and particulate-by-difference values depend on comparable total/dissolved measurements. A nominal rectangular sampling volume does not establish actual filtered effort or detection.
Average supplied Secchi disappearance and reappearance depths.
When to use this tool
Use Secchi Pair Midpoint when you already have disappearanceDepthMeters, reappearanceDepthMeters and need to average supplied Secchi disappearance and reappearance depths.
How to use the tool and how it works
- Enter disappearanceDepthMeters, reappearanceDepthMeters. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read meanDepthMeters, pairDifferenceMeters. Use the output convention below.
Require both depths>=0; return disappearance/2+reappearance/2 and disappearance-reappearance.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| disappearanceDepthMeters | Disappearance Depth Meters | Required. Finite number; minimum 0. |
| reappearanceDepthMeters | Reappearance Depth Meters | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| meanDepthMeters | Mean Depth Meters | Required. Finite number. |
| pairDifferenceMeters | Disappearance depth-reappearance depth, retaining sign. | Required. Finite number. |
{
"input": {
"disappearanceDepthMeters": 2.4,
"reappearanceDepthMeters": 2
},
"output": {
"meanDepthMeters": 2.2,
"pairDifferenceMeters": 0.3999999999999999
}
}Limitations and assumptions
- The halved sum avoids an overflowing direct sum. No observation, visibility protocol, optical property or water-quality interpretation is 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
Review original field and laboratory records with the complete survey or process model. Include calibration, temporal coverage, sampling efficiency and uncertainty when local rates, depth shifts or labels cannot establish the aquatic quantity of interest.
References
Similar or alternative tools
- Water Column Cast Depth Zero Shift
Correct a supplied recorded depth by a reference-zero offset.
- Current Meter Depth Fraction
Express supplied current-meter depth as a water-depth fraction.