Simulate canopy spectrum

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Description

Simulate a canopy spectrum using PROSAIL 5B

Usage

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PROSAIL(N = 1.5, Cab = 40, Car = 8, Cbrown = 0.0,
        Cw = 0.01, Cm = 0.009, psoil = 0, LAI = 1, 
        TypeLidf = 1, lidfa = -0.35, lidfb = -0.15,
        hspot = 0.01, tts = 30, tto = 10, psi = 0,
        parameterList = NULL, rsoil = NULL)

Arguments

N

Structure parameter

Cab

Chlorophyll content

Car

Carotenoid content

Cbrown

Brown pigment content

Cw

Equivalent water thickness

Cm

Dry matter content

psoil

Dry/Wet soil factor

LAI

Leaf area index

TypeLidf

Type of leaf angle distribution. See details section

lidfa

Leaf angle distribution. See details section

lidfb

Leaf angle distribution. See details section

hspot

Hotspot parameter

tts

Solar zenith angle

tto

Observer zenith angle

psi

Relative azimuth angle

parameterList

An optional object of class 'data.frame'. Function will iterate over rows of parameterList setting missing entries to default values. See examples section.

rsoil

An optional object of class 'Speclib' containing the background (soil) reflectance. Note that reflectance values must be in range [0...1].

Details

This function uses the FORTRAN code of PROSAIL model (Version 5B). For a general introduction see following web page and the links to articles provided there:

http://teledetection.ipgp.jussieu.fr/prosail/

The following table summarises the abbreviations of parameters and gives their units as used in PROSAIL. Please note that default values of all parameters were included with the intention to provide an easy access to the model and should be used with care in any scientific approach!

Parameter Description of parameter Units
N Leaf structure parameter NA
Cab Chlorophyll a+b concentration ug/cm2
Car Carotenoid concentration ug/cm2
Caw Equivalent water thickness cm
Cbrown Brown pigment NA
Cm Dry matter content g/cm2
LAI Leaf Area Index NA
psoil Dry/Wet soil factor NA
hspot Hotspot parameter NA
tts Solar zenith angle deg
tto Observer zenith angle deg
psi Relative azimuth angle deg

Functions for distribution of leaf angles within the canopy may work in two modes, which is controlled via TypeLidf:

  1. TypeLidf == 1 (default): lidfa is the average leaf slope and lidfb describes bimodality of leaf distribution. The following list gives an overview on typical settings:

    LIDF type lidfa lidfb
    Planophile 1 0
    Erectophile -1 0
    Plagiophile 0 -1
    Extremophile 0 1
    Spherical (default) -0.35 -0.15
  2. TypeLidf != 1: lidfa is the average leaf angle in degree (0 = planophile / 90 = erectophile); lidfb is 0

Value

An object of class Speclib. If parameterList is used, the parameter are stored in attributes table of Speclib.

Note

The function is based on the FORTRAN version of the PROSAIL-code initially developed by Stephane JACQUEMOUD, Jean-Baptiste FERET, Christophe FRANCOIS and Eben BROADBENT. SAIL component has been developed by Wout VERHOEF.

Author(s)

Lukas Lehnert

References

Jacquemoud, S., Verhoef, W., Baret, F., Bacour, C., Zarco-Tejada, P.J., Asner, G.P., Francois, C., and Ustin, S.L. (2009): PROSPECT + SAIL models: a review of use for vegetation characterization, Remote Sensing of Environment, 113, S56-S66.

See Also

PROSPECT, Speclib

Examples

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## Single spectrum
spectrum <- PROSAIL(N = 1.3)
plot(spectrum)

## Example using parameterList
## Test effect of leaf structure and LAI on spectra
parameter <- data.frame(N = c(rep.int(seq(0.5, 1.5, 0.5), 2)),
                        LAI = c(rep.int(0.5, 3), rep.int(1, 3)))
spectra <- PROSAIL(parameterList = parameter)

## Print attributes table
attribute(spectra)

## Plot spectra
plot(subset(spectra, LAI == 0.5), col = "red", ylim = c(0, 0.3))
plot(subset(spectra, LAI == 1), col = "green", new = FALSE)

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