Monsoon Onset Date Threshold Lookup

Audit caller monsoon-onset wet-run and following dry-break policy with fully observed confirmation window; incomplete future windows cannot confirm onset and no regional calendar is embedded.

Description

Monsoon onset policies often require a wet spell followed by a confirmation period without an excessive dry break.

Monsoon onset policies often require a wet spell followed by a confirmation period without an excessive dry break. Incomplete following observations cannot confirm an onset under this policy.^[1]

Audit caller monsoon-onset wet-run and following dry-break policy with fully observed confirmation window; incomplete future windows cannot confirm onset and no regional calendar is embedded.

When to use Monsoon Onset Date Threshold Lookup

Use this tool to audit caller monsoon-onset wet-run and following dry-break policy with fully observed confirmation window; incomplete future windows cannot confirm onset and no regional calendar is embedded.

Prepare the observed sounding, cloud records or forecast verification data. Check pressure and height coordinates, wind conventions and the stated units.

How to use Monsoon Onset Date Threshold Lookup and understand its results

Prepare the observed sounding, cloud records or forecast verification data. Check pressure and height coordinates, wind conventions and the stated units.
Enter dailyPrecipitationMm, callerMinimumWetRunDays, callerWetDayThresholdMm, callerFollowingDryWindowDays, callerMaximumConsecutiveDryDays using the field table and calculation rules, then run the tool.
Read candidateOnsetIndices, acceptedOnsetIndices, firstAcceptedOnsetIndex, acceptedOnsetFound. 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
dailyPrecipitationMm	Daily precipitation mm	list of number	Required
callerMinimumWetRunDays	Caller minimum wet run days	integer	Required
callerWetDayThresholdMm	Caller wet day threshold mm	number	Required
callerFollowingDryWindowDays	Caller following dry window days	integer	Required
callerMaximumConsecutiveDryDays	Caller maximum consecutive dry days	integer	Required

Enter nonnegative daily rain, a positive wet-day threshold and positive integer wet-run and following-window lengths. A wet day meets the threshold inclusively. Use starts of qualifying maximal wet runs; inspect the following window beginning after the minimum wet-run length. Return zero-based candidates and accepted starts, with −1 and false when none qualify. Rain-series length times following-window length must not exceed one million.

accept wet-run start when its full confirmation window is observed and maximum dry run ≤ caller limit

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

Output field	Meaning	Value type
candidateOnsetIndices	Candidate onset indices	list of number
acceptedOnsetIndices	Accepted onset indices	list of number
firstAcceptedOnsetIndex	First accepted onset index	number
acceptedOnsetFound	Accepted onset found	boolean

json

{
  "input": {
    "dailyPrecipitationMm": [
      0,
      5,
      10,
      0,
      0,
      3
    ],
    "callerMinimumWetRunDays": 2,
    "callerWetDayThresholdMm": 5,
    "callerFollowingDryWindowDays": 2,
    "callerMaximumConsecutiveDryDays": 1
  },
  "output": {
    "candidateOnsetIndices": [
      1
    ],
    "acceptedOnsetIndices": [],
    "firstAcceptedOnsetIndex": -1,
    "acceptedOnsetFound": false
  }
}

Limitations and assumptions

Thresholds are caller-defined. No regional onset calendar, missing-day handling or forecast confirmation is embedded.

Numeric inputs and returned numeric values must be finite; an unrepresentable returned value 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. A successfully returned false flag is an evaluated outcome; its meaning is explained above.

Alternative or Complementary methods

Use Wet Spell Length Analyzer: Analyze full consecutive wet spell distribution at a caller inclusive precipitation threshold; supplied sequence must have no missing days and zero means no observed qualifying spell. For a complementary task, use Rainy Days Threshold Counter: Audit a supplied increasing rain-threshold policy over observed daily precipitation with coverage denominator; no missing-as-dry treatment or climate category lookup.

References

Monsoon Onset Date Threshold Lookup — tool.io

Similar or alternative tools

Wet Spell Length Analyzer
Analyze full consecutive wet spell distribution at a caller inclusive precipitation threshold; supplied sequence must have no missing days and zero means no observed qualifying spell.
Rainy Days Threshold Counter
Audit a supplied increasing rain-threshold policy over observed daily precipitation with coverage denominator; no missing-as-dry treatment or climate category lookup.