Thermimage (version 2.1)

Lw: Estimates downward facing longwave radiation (W/m2)

Description

Estimates downward facing longwave radiation (W/m2) using a relationship derived from Gabathuler et al 2001

Usage

Lw(Ta = 20, RH = 0.5, n = 0.5)

Arguments

Ta

Local air temperature (degrees Celsius), ~ 2 m above ground

RH

Local relative humidity (fractional value from 0 to 1)

n

Fractional cloud cover (fractional value from 0 to 1)

Value

• A value, vector of length one, corresponding to the incoming longwave radiation, units: W/m2.

Details

An alternative to Ld() for estimating incoming radiation by determining an offset temperature to account for the influence of atmospheric transmission loss. The incoming infrared radiation is estimated using the Stephan-Boltzmann relationship: emissivity*Stephan Boltzmann constant*T^4

References

Gabathuler et al 2001. Parameterization of incoming longwave radiation in high mountain environments. Physical Geography 22: 99-114

See Also

Ld

Examples

## The function is currently defined as
function (Ta = 20, RH = 0.5, n = 0.5) 
{
    AT <- Ta + 273.15
    RH.pct <- RH * 100
    Ko <- n
    Lw <- StephBoltz() * (-21 * Ko + AT)^4 + 0.84 * RH.pct - 57
    Lw
  }

# Example calculation:
Ta<-30
RH<-0.5
n<-0
Lw(Ta, RH, n)