weathermetrics (version 1.2.2)

heat.index: Calculate heat index.

Description

heat.index creates a numeric vector of heat index values from numeric vectors of air temperature and either relative humidity or dew point temperature.

Usage

heat.index(t = NA, dp = c(), rh = c(), temperature.metric = "fahrenheit", output.metric = NULL, round = 0)

Arguments

t

Numeric vector of air temperatures.

dp

Numeric vector of dew point temperatures.

rh

Numeric vector of relative humidity (in %).

temperature.metric

Character string indicating the temperature metric of air temperature and dew point temperature. Possible values are 'fahrenheit' or 'celsius'.

output.metric

Character string indicating the metric into which heat index should be calculated. Possible values are 'fahrenheit' or 'celsius'.

round

Integer indicating the number of decimal places to round converted value.

Value

A numeric vector of heat index values in the metric specified by output.metric. (If output.metric is not specified, heat index will be returned in the same metric in which air temperature was input, specified by temperature.metric.)

Details

Include air temperature (t) and either dew point temperature (dp) or relative humdity (rh). You cannot specify both dew point temperature and relative humidity-- this will return an error. Heat index is calculated as NA when impossible values of dew point temperature or humidity are input (e.g., humidity above 100% or below 0%, dew point temperature above air temperature).

References

Anderson GB, Bell ML, Peng RD. 2013. Methods to calculate the heat index as an exposure metric in environmental health research. Environmental Health Perspectives 121(10):1111-1119.

National Weather Service Hydrometeorological Prediction Center Web Team. Heat Index Calculator. 30 Jan 2015. http://www.wpc.ncep.noaa.gov/html/heatindex.shtml. Accessed 18 Dec 2015.

Rothfusz L. 1990. The heat index (or, more than you ever wanted to know about heat index) (Technical Attachment SR 90-23). Fort Worth: Scientific Services Division, National Weather Service.

R. Steadman, 1979. The assessment of sultriness. Part I: A temperature-humidity index based on human physiology and clothing science. Journal of Applied Meteorology, 18(7):861--873.

Examples

# Calculate heat index from temperature (in Fahrenheit)
# and relative humidity.

data(suffolk)
suffolk$heat.index <- heat.index(t = suffolk$TemperatureF,
                                 rh = suffolk$Relative.Humidity)
suffolk

# Calculate heat index (in Celsius) from temperature (in
# Celsius) and dew point temperature (in Celsius).

data(lyon)
lyon$heat.index <- heat.index(t = lyon$TemperatureC,
                              dp = lyon$DewpointC,
                              temperature.metric = 'celsius',
                              output.metric = 'celsius')
lyon