fRTM: Forward implementation of coupled Radiative Transfer Models.

In MarcoDVisser/ccrtm: Coupled Chain Radiative Transfer Models

Forward implementation of coupled Radiative Transfer Models.

Description

Forward implementation of coupled Radiative Transfer Models.

Usage

fRTM(fm = rho + tau ~ prospect5 + foursail, pars = NULL, wl = 400:2500)

Arguments

fm	A formula specifying which rtm to run (see details).
pars	a named list of named parameter vectors for all models. The parameter list for a model call as rho ~ prospect + foursail, therefore, contains two vectors: the first with parameters for prospect and the second with parameters for foursail. See ?getDefaults for an example of a parameter list. If left empty default parameters are generated.
wl	wavelengths (in nm) add only if certain wavelengths are required as output. Input is expected to integers between 400 and 2500, or will be forced to be an integer. Integers outside the 400:2500 range will not be returned.

Details

Formula: In general the form of the formula specifies the both the expected output (left hand) and the different models you would like to couple to generate the output (right hand).

Models: At current the following radiative transfer models are implemented

Example of a formula	Model
rho ~ prospect5	prospect5
rho ~ prospectd	prospectd
rho ~ prospect5 + foursail	PROSAIL
rho ~ prospect5 + foursail	PROSAIL
rho ~ prospectd + foursail2	PROSAIL
rho ~ prospectd + prospect5 + foursail2	PROSAIL2*
rho ~ prospectd + foursail2b	PROSAIL2b*
rho ~ prospectd + foursail + flim + sky	INFORM**
rho ~ prospectd + foursail + flim	INFORM**

• Note that the formula "rho ~ prospectd + foursail2" is the same as "rho ~ prospectd + prospectd + foursail2" and both expect a names list of 3 parameter vectors (leaf type 1, leaf type 2, and the canopy parameters).

** INFORM is currently restricted to a lower-level function only. See the cctrm github readme page on how to use it.

In the above examples with additive components, prospectd can be replaced with prospect5 - or vice versa - if so desired. See the help files for details on each right hand component. For instance, ?foursail provides more elaboration on the 4SAIL model and gives an example for lower-level implementations of each component model.

Tranmission can also be returned if specified in the left-hand component of the formula:

Formula	Model
rho + tau ~ prospect5	prospect5
rho + tau ~ prospectd + foursail	4SAIL

The examples above indicate that the users wishes to predict transmission next to reflectance. More specifically, The first returns leaf reflectance and transmission while the second returns 4 components of canopy reflectance and canopy transmission in the solar and viewing direction.

More details are given in ?cctrm.

Questions and requests can be made on the ccrtm github page.

Value

spectra matrix with reflectance (and transmission, depending on the formula inputs). See seperate model helpfiles for details.

Examples

## setup graphics for plots
oldpar<-par()
par(mfrow=c(3,2))

## get reflectance for a leaf
ref <- fRTM(rho~prospect5)
plot(ref,main="Prospect 5")

## get reflectance and transmission for a leaf
reftrans <- fRTM(rho+tau~prospect5)
plot(reftrans,main="Prospect 5")

## get reflectance for a single layered canopy
ref <- fRTM(rho~prospect5+foursail)
plot(ref,main="Prospect 5 + 4SAIL")

## get reflectance for a 2 layered canopy with two leaf types
ref <- fRTM(rho~prospectd+prospect5+foursail2)
plot(ref,main="Prospect D + Prospect 5  + 4SAIL2")

## edit the parameters: sparse vegetation LAI
parlist <- getDefaults(rho~prospectd+prospect5+foursail2)
parlist$foursail2["LAI"] <- 0.05

## update reflectance
ref <- fRTM(rho~prospect5+prospectd+foursail2,parlist)
plot(ref,main="LAI=0.05")

## change leaf area index to dense vegetation
parlist$foursail2["LAI"]<-8.5

## update reflectance
ref <- fRTM(rho~prospect5+prospectd+foursail2,parlist)
plot(ref,main="LAI=8.5")

par(oldpar)

MarcoDVisser/ccrtm documentation built on Feb. 19, 2025, 1:15 p.m.