Ocean PH Drop Decade Rate

Fit observed pH trend and its multiplicative hydrogen-activity interpretation on one consistent pH scale; pH is logarithmic, and activity is not molar concentration without an activity convention.

Description

pH is logarithmic in hydrogen activity.

pH is logarithmic in hydrogen activity. A small pH trend implies a multiplicative activity change rather than a linear concentration increment.

Fit observed pH trend and its multiplicative hydrogen-activity interpretation on one consistent pH scale; pH is logarithmic, and activity is not molar concentration without an activity convention.

When to use Ocean PH Drop Decade Rate

Use this tool to fit observed pH trend and its multiplicative hydrogen-activity interpretation on one consistent pH scale; pH is logarithmic, and activity is not molar concentration without an activity convention.

Gather the water, wave, current or profile observations and any supplied calibration constants. Confirm units and the stated coordinate and pressure conventions.

How to use Ocean PH Drop Decade Rate and understand its results

Gather the water, wave, current or profile observations and any supplied calibration constants. Confirm units and the stated coordinate and pressure conventions.
Enter timesYears, phValues using the field table and calculation rules, then run the tool.
Read fittedPhChangePerDecade, hydrogenActivityMultiplierPerDecade, fitRSquared. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
timesYears	Times years	list of number	Required
phValues	Ph values	list of number	Required

Use increasing years and aligned pH observations on one scale. Regress pH and return signed decadal change, activity multiplier and R².^[1]

Each sequence checked for increasing order must contain at least two strictly increasing values. The least-squares fit needs at least two aligned observations and a varying independent variable; a constant dependent variable has reported R² of 1.

activity multiplier/decade = 10^(−10 × fitted pH slope/year)

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
fittedPhChangePerDecade	Fitted ph change per decade	number
hydrogenActivityMultiplierPerDecade	Hydrogen activity multiplier per decade	number
fitRSquared	Fit r squared	number

json

{
  "input": {
    "timesYears": [
      0,
      1,
      2
    ],
    "phValues": [
      8,
      7.9,
      7.8
    ]
  },
  "output": {
    "fittedPhChangePerDecade": -1.0000000000000009,
    "hydrogenActivityMultiplierPerDecade": 10.000000000000021,
    "fitRSquared": 1
  }
}

Limitations and assumptions

Activity is not molar concentration without a convention, and an observed trend is not a forecast.

Numbers and computed results must be finite; overflow produces an error. Numeric lists are limited to 100,000 entries; the rules above may require smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Omega Aragonite Carbonate State: Calculate aragonite ion-activity saturation on a caller consistent molal/activity Ksp convention; conditional seawater concentration Ksp must not be mixed with separate activity corrections. For a complementary task, use Nino34 Anomaly Classifier: Screen supplied monthly Nino3.4 anomalies using a caller running-window/consecutive-phase policy; inputs must be contiguous months on one baseline and outputs are not an official ENSO designation.

References

Ocean PH Drop Decade Rate — tool.io

Similar or alternative tools

Omega Aragonite Carbonate State
Calculate aragonite ion-activity saturation on a caller consistent molal/activity Ksp convention; conditional seawater concentration Ksp must not be mixed with separate activity corrections.
Nino34 Anomaly Classifier
Screen supplied monthly Nino3.4 anomalies using a caller running-window/consecutive-phase policy; inputs must be contiguous months on one baseline and outputs are not an official ENSO designation.