UVI {photobiologyWavebands}

Calculate UV Index (UVI) from spectral irradiance

Description

UVI (UV Index) is a unitless quantity based on erythema biological spectral weighting function (BSWF), that gives an easy to interpret UV measure, mainly meant for informing general public about sunburn risk.

Usage

UVI(spct, std = "NOAA", integer_UVI = FALSE)

Arguments

spct

a source.spct object

std

character One of "WWO", "NOAA".

integer_UVI

logical Return a positive integer value according to WWO recommended practice or a numeric value.

Details

Two different definitions of UV Index are implemented in this package. Setting std="NOAA" follows the definition in Kiedron et al. (2007) but using CIE98 as SWF. NOAA definition discards wavelengths shorter than 286.5 nm as when calculated based on spectral data from Brewer instruments. "WMO" uses the internationally accepted lower limit at 250 nm (see WHO, 2002). "NOAA" is the default as this is safer with noisy data for solar radiation measured at ground level, and in this case the value of UVI should be correct, and almost identical except for errors caused by noise at shorter wavelengths. However, when calculating UVI from radiation spectra from UV lamps, "WMO" should be used, as most UV lamps do emit some radiation between 250 nm and 286.5 nm.

Value

depending on the argument passed to integer_UVI, a numeric (FALSE) or integer (TRUE) value for the unitless UVI.

Note

The default is to return a numeric value not rounded into a value in the integer-number based recommended UVI scale. This is done to avoid loss of precision in cases when additional operations, such as averaging, are applied to the UVI values.

References

World Health Organization, World Meteorological Organization, United Nations Environment Programme & International Commission on Non-Ionizing Radiation Protection. (2002) Global Solar UV Index: A Practical Guide. World Health Organization, Geneva. ISBN 9241590076. https://apps.who.int/iris/handle/10665/42459

P. Kiedron, S. Stierle and K. Lantz (2007) Instantaneous UV Index and Daily UV Dose Calculations. NOAA-EPA Brewer Network. https://www.esrl.noaa.gov/gmd/grad/neubrew/docs/UVindex.pdf

Examples

UVI(sun.spct)
UVI(sun.spct, "WMO")
UVI(sun.spct, integer_UVI = TRUE)