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# heat_apptemp

Compute apparent temperature.

Available in version 6.4.0 and later.

## Prototype

```load "\$NCARG_ROOT/lib/ncarg/nclscripts/csm/heat_stress.ncl"  ; This library is automatically loaded
; from NCL V6.5.0 onward.
; No need for user to explicitly load.

function heat_apptemp (
t          : numeric,
vp         : numeric,
w10        : numeric,
iounit [3] : integer,
opt        : integer
)

return_val [dimsizes(t)] :  float or double
```

## Arguments

t

Scalar or array containing temperature(s) [ units see iounit ].

vp

Scalar or array containing vapor pressure (Pa).

w10

Scalar or array containing 10-meter winds (m/s).

iounit

An integer array of length 2 which specifies the units of the input t and returned heat_index:

• iounit(0)=0 input t (degC)
• iounit(0)=1 input t (degK)
• iounit(0)=2 input t (Farenheit)

• iounit(1)=0 input vp (hPa)
• iounit(1)=1 input vp (Pa)
• iounit(1)=2 input vp (kPa)

• iounit(2)=0 returns units degC
• iounit(2)=1 returns units degK
• iounit(2)=2 returns units Farenheit

opt

Currently not used. Set to False.

## Return value

A scalar or an array of the same size and shape as t. The output will be double if t or rh is of type double. The units are specified by iounit(1).

## Description

Wikipedia: Apparent temperature is the general term for the perceived outdoor temperature, caused by the combined effects of air temperature, relative humidity and wind speed.

```

REFERENCES:
Australian Bureau of Meteorology

http://www.bom.gov.au/info/thermal_stress/#atapproximation

Steadman, R.G., 1994: Norms of apparent temperature
in Australia, Aust. Met. Mag., 43, 1-16.

Buzan, J.R. et al (2015):
Implementation and comparison of a suite of heat stress metrics
within the Community Land Model version 4.5
Geosci. Model Dev., 8, 151-170, 2015
www.geosci-model-dev.net/8/151/2015/    doi:10.5194/gmd-8-151-2015
```

## Examples

Example 1:

```   t   = 30.5      ; C
vp  = 20.0      ; Pa
w10 = 10.0      ; m/s
at  = heat_apptemp(t, vp, w10, (/0,1,0/), 0)
print(at)
```
The output is:
```
Variable: at
Type: float
Total Size: 4 bytes
1 values
Number of Dimensions: 1
Dimensions and sizes:	[1]
Coordinates:
Number Of Attributes: 5
long_name :	apparent temperature
units :	degC
reference_1 :	Steadman, R.G., 1994: Norms of apparent temperature in Australia, Aust. Met. Mag., 43, 1-16
reference_2 :	Buzan et al (2015): eq (1)
NCL :	heat_apptemp
(0)	19.566

```