Slot: Homogenisation Status (source_homogenisation_status)

For station-based products, whether values have been homogenised. Mandatory for station-based products; GHCN-D = not_homogenised, GHCN-M v4 = homogenised.

Tier: conditionally_core

Why this slot matters

Using a non-homogenised station product (e.g. GHCN-Daily) for trend work without saying so is a known trap: station moves and instrument changes masquerade as climate signal. Mandatory for station-based products.

In plain terms

Weather stations get moved, replaced, or re-instrumented over the decades, which creates artificial jumps in their records. "Homogenised" data has had those jumps statistically corrected; "not homogenised" data is raw, as observed.

URI: envar:slot/source_homogenisation_status

Applicable Classes

Name	Description	Modifies Slot
SourceDataset	The upstream gridded / station product the exposure values originate from	no

Properties

Type and Range

Property	Value
Range	HomogenisationStatusEnum
Domain Of	SourceDataset

Cardinality and Requirements

Property	Value

Examples

Value
not_homogenised

See Also

• https://en.wikipedia.org/wiki/Homogenization_(climate)

Identifier and Mapping Information

Annotations

property	value
tier	conditionally_core
tier_context	not machine-decidable — the stated context is "station-based products", which cannot be read reliably off the sidecar (no slot declares station-ness). No rule and no checker predicate; the slot scores as Optional out of context by design.
justification	Using a non-homogenised station product (e.g. GHCN-Daily) for trend work without saying so is a known trap: station moves and instrument changes masquerade as climate signal. Mandatory for station-based products.
explanation	Weather stations get moved, replaced, or re-instrumented over the decades, which creates artificial jumps in their records. "Homogenised" data has had those jumps statistically corrected; "not homogenised" data is raw, as observed.

Schema Source

• from schema: https://w3id.org/linkml/microschemas/envar

Mappings

Mapping Type	Mapped Value
self	envar:source_homogenisation_status
native	envar:source_homogenisation_status

LinkML Source

name: source_homogenisation_status
annotations:
  tier:
    tag: tier
    value: conditionally_core
  tier_context:
    tag: tier_context
    value: not machine-decidable — the stated context is "station-based products",
      which cannot be read reliably off the sidecar (no slot declares station-ness).
      No rule and no checker predicate; the slot scores as Optional out of context
      by design.
  justification:
    tag: justification
    value: 'Using a non-homogenised station product (e.g. GHCN-Daily) for trend work
      without saying so is a known trap: station moves and instrument changes masquerade
      as climate signal. Mandatory for station-based products.'
  explanation:
    tag: explanation
    value: Weather stations get moved, replaced, or re-instrumented over the decades,
      which creates artificial jumps in their records. "Homogenised" data has had
      those jumps statistically corrected; "not homogenised" data is raw, as observed.
description: For station-based products, whether values have been homogenised. Mandatory
  for station-based products; GHCN-D = `not_homogenised`, GHCN-M v4 = `homogenised`.
title: Homogenisation Status
examples:
- value: not_homogenised
  description: e.g. GHCN-Daily station observations
from_schema: https://w3id.org/linkml/microschemas/envar
see_also:
- https://en.wikipedia.org/wiki/Homogenization_(climate)
rank: 1000
domain_of:
- SourceDataset
range: HomogenisationStatusEnum