Description Usage Arguments Details Value Author(s) References See Also Examples

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

1 | ```
rnl(Tmax,Tmin,sol_rad,vap_pres,extraT,tal)
``` |

`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. |

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.

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

Jedrzej S. Bojanowski

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

1 | ```
rnl(Tmax=25.1,Tmin=19.1,sol_rad=14.5,vap_pres=2.1,extraT=23.5,tal=0.8)
``` |

```
[1] 3.534035
```

sirad documentation built on May 31, 2017, 1:44 a.m.

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