Slot: Equation Variant (equation_variant)

For derived heat metrics, the equation variant used. Mandatory for WBGT, HI, and UTCI: a Liljegren WBGT and an ACSM WBGT for the same inputs can differ by 2-3 °C.

Tier: conditionally_core

Why this slot matters

WBGT approximations diverge materially from the reference model — well beyond 2-3 °C in hot-humid conditions — so two studies using "WBGT" with different variants are measuring systematically different quantities; pooling them without this field mixes those quantities silently.

In plain terms

Well-known heat metrics have several published formulas that share one name but differ mathematically — like recipes with the same title from different cookbooks. This records which exact recipe was used to cook the number.

URI: envar:slot/equation_variant

Applicable Classes

Name	Description	Modifies Slot
DerivedHeatMetric	Methodology slots specific to derived heat metrics (WBGT, Heat Index, UTCI, a...	yes

Properties

Type and Range

Property	Value
Range	EquationVariantEnum
Domain Of	DerivedHeatMetric

Cardinality and Requirements

Property	Value

Examples

Value
liljegren_2008

See Also

• https://en.wikipedia.org/wiki/Wet-bulb_globe_temperature

Identifier and Mapping Information

Annotations

property	value
tier	conditionally_core
justification	WBGT approximations diverge materially from the reference model — well beyond 2-3 °C in hot-humid conditions — so two studies using "WBGT" with different variants are measuring systematically different quantities; pooling them without this field mixes those quantities silently.
explanation	Well-known heat metrics have several published formulas that share one name but differ mathematically — like recipes with the same title from different cookbooks. This records which exact recipe was used to cook the number.

Schema Source

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

Mappings

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

LinkML Source

name: equation_variant
annotations:
  tier:
    tag: tier
    value: conditionally_core
  justification:
    tag: justification
    value: WBGT approximations diverge materially from the reference model — well
      beyond 2-3 °C in hot-humid conditions — so two studies using "WBGT" with different
      variants are measuring systematically different quantities; pooling them without
      this field mixes those quantities silently.
  explanation:
    tag: explanation
    value: Well-known heat metrics have several published formulas that share one
      name but differ mathematically — like recipes with the same title from different
      cookbooks. This records which exact recipe was used to cook the number.
description: 'For derived heat metrics, the equation variant used. Mandatory for WBGT,
  HI, and UTCI: a Liljegren WBGT and an ACSM WBGT for the same inputs can differ by
  2-3 °C.'
title: Equation Variant
examples:
- value: liljegren_2008
  description: Liljegren et al. 2008 outdoor WBGT formulation
from_schema: https://w3id.org/linkml/microschemas/envar
see_also:
- https://en.wikipedia.org/wiki/Wet-bulb_globe_temperature
rank: 1000
domain_of:
- DerivedHeatMetric
range: EquationVariantEnum