rnl: Net longwave radiation

In sirad: Functions for Calculating Daily Solar Radiation and Evapotranspiration

Description

'rnl' computes daily net energy flux emitted by the Earth's surface.

Usage

rnl(Tmax,Tmin,sol_rad,vap_pres,extraT,tal)

Arguments

Tmax	Vector of length n containing daily maximum temperature [C].
Tmin	Vector of length n containing daily minumum temperature [C].
sol_rad	Vector of length n of daily solar radiation [MJm-2d-1].
vap_pres	Vector of length n of mean daily vapour pressure [kPa].
extraT	Vector of length n of extraterrestrial solar radiation [MJm-2d-1].
tal	Clear sky transmissivity.

Details

According to the Stefan-Boltzmann law, the longwave energy emission is proportional to the absolute temperature of the surface raised to the fourth power. This longwave energy is corrected by two factors: humidity ('ea') and cloudiness (estimated based on relation of actual and potential solar radiation. See Allen et al. (1998) for details.

Value

Vector of length n of daily net longwave radiation. [MJm-2d-1]

Author(s)

Jedrzej S. Bojanowski

References

Allen, R.G., L.S. Pereira, D. Raes, and M. Smith. 1998. Crop Evapotranspiration: Guidelines for computing crop water requirements. Irrigation and Drainage Paper 56, Food and Agriculture Organization of the United Nations, Rome, pp. 300.

See Also

See 'ea', 'extrat' and 'cst' to calculate necessary input data.

Examples

rnl(Tmax=25.1,Tmin=19.1,sol_rad=14.5,vap_pres=2.1,extraT=23.5,tal=0.8)

Example output

[1] 3.534035

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