# transmissivity: Transmissivity In EcoHydRology: A Community Modeling Foundation for EcoHydrology

## Description

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

## Usage

 `1` ```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.

## Author(s)

M. Todd Walter, Josephine Archibald

## 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

 ```1 2 3 4 5 6``` ```## 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") ```

EcoHydRology documentation built on May 2, 2019, 4:47 p.m.