Apparent Temperature (radiation)

The radiation-inclusive Apparent Temperature (AT) extends Steadman's apparent temperature with a term for the net radiation absorbed by the body, so that solar and thermal loading raise the perceived temperature above the shade value.

It is the operational form published by the Australian Bureau of Meteorology:

AT = Ta + 0.348·e − 0.70·va + 0.70·q/(va + 10) − 4.25 (Ta in °C)

where e is the ambient water-vapour pressure in hPa, va is the 10 m wind speed and q is the net radiation absorbed per unit area of body surface.

More information:

• Steadman, R. G. Norms of apparent temperature in Australia. Aust. Met. Mag. 43, 1–16 (1994). https://doi.org/10.1071/es94001
• Australian Government Bureau of Meteorology. Thermal Comfort observations — About the formula for the apparent temperature. https://www.bom.gov.au/info/thermal_stress/#atapproximation

How to use

You need 2 m air temperature in Kelvin, 10 m wind speed in metres per second, relative humidity as a percentage and the net radiation absorbed per unit body-surface area q in W m⁻².

It returns the apparent temperature in Kelvin.

calculate_apparent_temperature_radiation(2m_temperature, 10m_wind_speed, relative_humidity_percent, q)

Interpret the output

Relative to the non-radiation calculate_apparent_temperature, this form adds the radiation term 0.70·q/(va + 10), so a positive radiation load makes the apparent temperature warmer.

q is caller-supplied: it is the net radiation absorbed per unit area of body surface (W m⁻²), analogous to how cossza is supplied to other functions. It is not an NWP surface radiation flux and not the mean radiant temperature — you must derive and supply q yourself for your application.