bc {sirad}

Bristow-Campbell model

Description

'bc' calculates daily solar radiation based on daily temperature range using Bristow-Campbell model.

Usage

bc(days, lat, BCb,extraT=NULL, Tmax, Tmin, BCc = 2, tal)

Arguments

days

Vector of class 'Date' of length n.

lat

Latitude in decimal degrees.

BCb

Bristow-Campbell model coefficient 'B'.

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].

BCc

Bristow-Campbell model coefficient 'C' usually equaled to 2.

tal

Clear sky transmissivity.

Details

Bristow and Campbell proposed a method for estimating solar radiation from air temperature measurements. They developed an empirical relationship to express the daily total atmospheric transmittance as a function of daily range in air temperature.

Value

Vector of length n of daily solar radiation [MJm-2].

Note

'Tmax', 'Tmin' can contain NA's, but length of vectors 'Tmax', 'Tmin' and 'days' has to be the same.

Author(s)

Jedrzej S. Bojanowski

References

Bristow, K.L., Campbell, G.S. 1984. On the relationship between incoming solar radiation and daily maximum and minimum temperature. Agriculture and Forest Meteorology, 31:159-166.

See Also

'bccal' to calibrate model using reference data, 'bcauto' to perform auto-calibration, and 'ha' to use Hargreaves model to calculate solar radiation based on temperature range.

Examples

require(zoo)
data(Metdata)
B <- 0.11
tmax <- Metdata$meteo$TEMP_MAX
tmin <- Metdata$meteo$TEMP_MIN
days <- Metdata$meteo$DAY
lat <- Metdata$LATITUDE
plot(zoo(bc(days, lat, BCb=B,extraT=NULL, tmax, tmin, BCc=2, tal=0.76),order.by=days))