sirad (version 2.3-3)

cst: Estimate clear sky transmissivity

Description

Function estimates a clear sky transmissivity based on reference data (e.g. measured)

Usage

cst(RefRad, days, lat, extraT=NULL, perce = 3, sepYear = FALSE, stat='median')

Arguments

RefRad

Vector of length n of reference solar radiation data [MJm-2]

days

Vector of class 'Date' of length n.

lat

Latitude in radians

extraT

Optional. Vector of length n of extraterrestrial solar radiation [MJm-2]. If 'NULL' then it is calculated by the function. Providing extraterrestrial solar radiation speeds up the computation

perce

Percent of days to be chosen as clear days

sepYear

Logical value. If 'TRUE' percent of days given by 'perce' of every single year are taken for calculation. If 'FALSE' percent of days given by 'perce' of all years are taken for calculation

stat

Method used to estimate final value of the clear sky transmissivity from the values derived from selected clear-sky days. Default is 'median' which is more conservative, while alternative 'max' is sensitive to outliers. If 'max' is used the value of 'perce' is not important. If 'stat' is numeric then (instead of 'median' or 'max') 'quantile' is used. 'Stat' is sent as quantile's 'probs' parameter. See ?quantile for details

Value

Numeric. Clear sky transmissivity.

See Also

cstRead

Examples

data(Metdata)
ref <- Metdata$meteo$RAD_MEA
i <- dayOfYear(Metdata$meteo$DAY)
latr <- radians(Metdata$LATITUDE)
cst(ref,i,latr)