EcoHydRology (version 0.4.12.1)

transmissivity: Transmissivity

Description

Transmissivity Fraction of direct solar radiation passing through the atmosphere based on the Bristow-Campbell eqn

Usage

transmissivity(Tx,Tn, A=0.75, C=2.4, opt="1day", JD=NULL)

Arguments

Tx

maximum daily temperature [C]

Tn

minimum daily temperature [C]

A

Maximum transmissivity in a location, varies with environmental conditions and elevation

C

Empirical partitioning coefficient - set to 2.4

opt

Options: "1day" uses the diurnal temperature change as Tx-Tn for any given day; "2day" depends on an average temperature change, i.e. the max temp today minus the average of the min temps of today and tomorrow; Users who do not have a continuous record of daily temperatures should use "missingdays" - note that this depends on JD input. If JD is null and "missingdays" is chosen the function will default to "1day"

JD

A vector of julian days corresponding to temp measurements. Only needed if using opt="missingdays"

Details

Can accept either single values or vectors for Tx,Tn and JD.

References

Bristow KL, Campbell GS. 1984. On the relationship between incoming solar radiation and daily maximum and minimum temperature. Agric Forest Meteorol; 31:150-166.

Examples

# NOT RUN {
##  Assuming the temperature measurements are consecutive days, default option:
transmissivity(Tx=c(10,10,10,10,10), Tn=c(1,2,6,9,2))
## Second option:
transmissivity(Tx=c(10,10,10,10,10), Tn=c(1,2,6,9,2), opt="2day")
##  When the days are not consecutive:
transmissivity(Tx=c(10,10,10,10,10), Tn=c(1,2,6,9,2), JD=c(250,265,300,320,321), opt="missingdays")
# }