Palmer Drought Severity Index Simplified Calculator
Explicit classic linear Palmer recurrence X=p Xprevious+Z/3 with independently calibrated Z; not complete PDSI spell-selection/soil calibration or absolute drought severity from precipitation. Caller independently establishes homogeneous observation coverage and model/reference applicability; not observed future climate, crop suitability or validated drought severity.
Description
A simplified Palmer recurrence carries a previous state through monthly anomaly inputs.
A simplified Palmer recurrence carries a previous state through monthly anomaly inputs.1
It does not calculate a complete soil-water balance or reproduce every operational PDSI convention. Use Palmer Drought Severity Index Simplified Calculator to evaluate the supplied inputs under the model explained below.
When to use Palmer Drought Severity Index Simplified Calculator
Use Palmer Drought Severity Index Simplified Calculator to evaluate the supplied inputs under the model explained below. Establish the units, measurement scope and model assumptions before entering values.
How to use Palmer Drought Severity Index Simplified Calculator and understand its results
- Establish the units, measurement scope and model assumptions before entering values.
- Enter Independently calibrated monthly palmer z, Caller previous palmer state, Caller persistence factor using the field table and validation rules below, then run the tool.
- Read Simplified monthly palmer states; interpret the units, signs, ordering and unknown-value placeholders described below.
- Correct reported input errors and rerun. Apply successful results according to their specific meanings and check the assumptions before using them in a decision.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| independentlyCalibratedMonthlyPalmerZ | Independently calibrated monthly palmer z | array of number | Required; constraints below |
| callerPreviousPalmerState | Caller previous palmer state | number | Required; constraints below |
| callerPersistenceFactor | Caller persistence factor | number | Required; constraints below |
Enter finite independently calibrated monthly Palmer Z values, a finite previous state and persistence from 0 to 1. Advance state in supplied order using persistence×previous+Z/3 and return every new state. Inputs may be signed and an empty monthly array returns empty states. No hydrologic calibration, spell selection or full operational Palmer algorithm is performed.
state[i]=persistence×state[i−1]+monthlyZ[i]/3 Use the field order, units and branch conditions described above.
| Output field | Meaning | Value type |
|---|---|---|
| simplifiedMonthlyPalmerStates | Simplified monthly palmer states | array of number |
{
"input": {
"independentlyCalibratedMonthlyPalmerZ": [
3,
-3
],
"callerPreviousPalmerState": 0,
"callerPersistenceFactor": 0.897
},
"output": {
"simplifiedMonthlyPalmerStates": [
1,
-0.10299999999999998
]
}
}Limitations and assumptions
It does not calculate a complete soil-water balance or reproduce every operational PDSI convention. Apply the exact scope and assumptions explained above.
All listed fields require explicit values. Unexpected fields, incorrect types, nonfinite numbers and sparse arrays fail validation. Domain-specific bounds, alignments and supported tokens are explained above; extremely large inputs or outputs can also be rejected. Input errors differ from successful false results, empty match lists and unknown-evidence placeholders.
Alternative or Complementary methods
Use Standardized Precipitation Evapotranspiration Index SPEI Calculator for a related task: A standardized precipitation-evapotranspiration index uses a calibrated water-balance distribution.
Use Standardized Precipitation Index SPI Calculator for a related task: A standardized precipitation index maps a calibrated probability onto a standard-normal scale.
References
Similar or alternative tools
- Standardized Precipitation Evapotranspiration Index SPEI Calculator
A standardized precipitation-evapotranspiration index uses a calibrated water-balance distribution.
- Standardized Precipitation Index SPI Calculator
A standardized precipitation index maps a calibrated probability onto a standard-normal scale.