sucal: Calibrate Supit-Van Kappel model

In sirad: Functions for Calculating Daily Solar Radiation and Evapotranspiration

Description

Function estimates Supit-Van Kappel model coefficients 'A', 'B' and 'C' based on reference data

Usage

sucal(days, lat, rad_mea, extraT=NULL, tmax, tmin, cc)

Arguments

days	Vector of class 'Date' of length n.
lat	Latitude in decimal degrees.
rad_mea	Vector of length n containing reference (e.g. measured) solar radiation [MJm-2].
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
tmax	Vector of length n containing daily maximum temperature [C].
tmin	Vector of length n containing daily minumum temperature [C].
cc	Vector of length n containing daily cloud coverage [octas].

Details

Function estimates Supit-Van Kappel model coefficients 'A', 'B' and 'C' based on reference (e.g. measured) solar radiation data. It performs a linear regression.

Value

Vector of length 3:

Sa	Supit-Van Kappel 'A' coefficient
Sb	Supit-Van Kappel 'B' coefficient
Sc	Supit-Van Kappel 'C' coefficient
Sr2	Coefficient of determination of performed linear regression

Author(s)

Jedrzej S. Bojanowski

References

Supit, I. 1994. Global radiation. Publication EUR 15745 EN of the Office for Official Publications of the EU, Luxembourg.
Supit, I., Kappel, R.R. van, 1998. A simple method to estimate global radiation. Solar Energy, 63:147-160.

See Also

'su'.

Examples

data(Metdata)
tmax <- Metdata$meteo$TEMP_MAX
tmin <- Metdata$meteo$TEMP_MIN
days <- Metdata$meteo$DAY
lat <- Metdata$LATITUDE
rad_mea <- Metdata$meteo$RAD_MEA
CC <- Metdata$meteo$CLOUD_DAYTIME_TOTAL
sucal(lat=lat,days=days,rad_mea, extraT=NULL,tmax=tmax, tmin=tmin,cc=CC)

Example output

         Sa          Sb          Sc         Sr2 
 0.07569503  0.51465044 -0.29283122  0.96217060 

sirad documentation built on May 2, 2019, 4:41 p.m.