bccal: Calibrate Bristow-Campbell model In sirad: Functions for Calculating Daily Solar Radiation and Evapotranspiration

Description

Function estimates Bristow-Campbell model coefficient 'B' based on reference data

Usage

 `1` ```bccal(lat, days, rad_mea,extraT=NULL,BCc=2,Tmax, Tmin, tal) ```

Arguments

 `lat` Latitude in decimal degrees. `days` Vector of class 'Date' of length n. `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 `BCc` Bristow-Campbell model coefficient 'C' usually equaled to 2. `Tmax` Vector of length n containing daily maximum temperature [C]. `Tmin` Vector of length n containing daily minumum temperature [C]. `tal` Clear sky transmissivity.

Details

Function estimates Bristow-Campbell model coefficient 'B' based on reference (e.g. measured) solar radiation data. It performs a non-linear least squeres regression.

Value

 `BCb` Bristow-Campbell 'B' coefficient

Author(s)

Jedrzej S. Bojanowski

References

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

'bc', and 'bcauto' to perform auto-calibration

Examples

 ```1 2 3 4 5 6 7``` ```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 bccal(lat,days,rad_mea,extraT=NULL,BCc=2,tmax,tmin, tal=0.76) ```

sirad documentation built on May 29, 2017, 10:04 a.m.