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All parameters are stored in MARS in units of Kelvin (K).

ECMWF mean radiant temperature is an ancillary variable from which the globe temperature is derived.

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It is derived from 2m air temperature and 2m vapour pressure.  The Heat Index is given in °C.

The Humidex is described in terms of comfort.

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• Ta is the 2m air temperature (in °C).
• RH is the 2m relative humidity (in %).
• v is the wind speed at 1.2 m above the ground (in m/s).

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It is derived from 2m air temperature, 2m relative humidity, 10m wind speed, and Mean Radiant Temperature.

The Universal Thermal Climate Index is described in terms of the human internal heat or cold stress experienced while trying to maintain a thermal equilibrium with the outdoor environment.

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MRT=[(Tg + 273.15)⋅4 + 1.1⋅108v⋅0.6⋅ε⋅D⋅0.4 × (Tg−Ta)]⋅1/4−273.15

where:

• MRT is the Mean Radiant Temperature (in °C)
• Ta is the 2m air temperature Ta (in °C)
• v is the wind speed at 1.1m (in m/s)
• ε is the emissivity set to 0.95
• D is the diameter of sphere  set to 0.15 m.

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