LIBERTY

LIBERTY (Leaf Incorporating Biochemistry Exhibiting Reflectance and Transmittance Yields) is a radiative transfer model developed by Dawson et al., (1998) to simulate coniferous needle optical properties. The cellular structure of needles are represented by powders (grains with inter granular air cavities) in LIBERTY following Melamed's (1963) theory of the interaction of light with powders. Other radiative transfer process models such as PROSPECT or LEAFMOD model a leaf as a series of turbid homogeneous plates with Lambertian reflecting surfaces with gaps between and may be more appropriate for broadleaf species.

LIBERTY is a general purpose model for predicting the reflectance and transmittance spectra of a coniferous needle, or stack of coniferous needles in the visible and near infrared wavelengths (400 - 2500 nm). As needles are treated as an aggregation of cells, with multiple radiation scattering between cells, output spectra are a function of three structural parameters and the combined absorption coefficients of needle biochemical constituants. LIBERTY is simple to use with the user being prompted for input values and the model output written to an external file for use with graphing and spreadsheet executables as well as for coupling with vegetation canopy or ecosystem models. It is written in C, calling on external absorption coefficient files, and has been successfully compiled for the following platforms: MS-DOS; SUN Microsystems Solaris; and Silicon Graphics IRIX. In addition, a Windows GUI has been developed by S. G. Lebanc for the use of those less familiar with DOS.

To download a zip file with LIBERTY compiled in the format for your operating system please 'click' on the appropriate link below. Alternatively, download the User guide pdf for a detailed discription of LIBERTY with a list variables required to parameterise the model and description of possible output formats.

To locate Terry Dawson's original article on LIBERTY please follow this ... link ...

This LIBERTY web page and its contents are hosted by Alasdair Mac Arthur Operations Manager of the NERC Field Spectroscopy Facility on behalf of Terry Dawson.

Site created 10th October 2006.

References

DAWSON, T. P., CURRAN, P. J. & PLUMMER, S. E. (1998) LIBERTY - Modeling the Effects of Leaf Biochemical Concentration on Reflectance Spectra. Remote Sensing of Environment, 65, 50-60.

MELAMED, M. T. (1963) Optical properties of powders. Part 1 Optical absorption coefficients and the absolute value of the diffuse reflectance. Journal of Applied Physics, 34, 560-570.