transmissivity: Transmissivity

In EcoHydRology: A Community Modeling Foundation for Eco-Hydrology

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.

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

##  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")

Example output

Loading required package: operators

Attaching package: 'operators'

The following objects are masked from 'package:base':

    options, strrep

Loading required package: topmodel
Loading required package: DEoptim
Loading required package: parallel

DEoptim package
Differential Evolution algorithm in R
Authors: D. Ardia, K. Mullen, B. Peterson and J. Ulrich

Loading required package: XML
[1] 0.70381331 0.65825139 0.24628825 0.01064085 0.65825139
[1] 0.68642091 0.49266867 0.09198497 0.31132127 0.66119471
[1] 0.62046378 0.58986763 0.31366064 0.01338118 0.69685188

EcoHydRology documentation built on May 2, 2019, 8:28 a.m.