Program frt, change log. program frt23 c Forest reflectance and transmittance, and its inversion. c (C) Andres Kuusk & Tiit Nilson c Kuusk, A. and Nilson, T. A directional multispectral forest c reflectance model, Remote Sens. Environ., 2000, 72(2): c 244-252. c Version 12.2024. [27.08.2025] December_2023-August_2025: Major revision of the code structure, The format of input files is changed. The loops (ijob=1 and ijob=2) are organized in the main program. Updated the manual. ----------- program frt14 c Forest reflectance and transmittance, and its inversion. c (C) Andres Kuusk & Tiit Nilson c FRT14, Version 06.2025. c Contact: A. Kuusk, Tartu Observatory, Estonia, andres@bgf.ee The version of FRT13, the format of input files is that of FRT23. The probability to see sunlit foliage in tree crowns is corrigated for the overlaping of tree crowns and for the transparency of tree crowns. [16.07.2025] July 2025: - Rewrote the module rcone(..) - the calculation of the path length inside the tree crown - cone+cylinder. =========== program frt13 c Forest reflectance and transmittance, and its inversion. c (C) Andres Kuusk & Tiit Nilson c Kuusk, A. and Nilson, T. A directional multispectral forest c reflectance model, Remote Sens. Environ., 2000, 72(2): c 244-252. c Version 04.2013. c Contact: A. Kuusk, Tartu Observatory, Estonia, andres@aai.ee [17.04.2013] April 2013: - Added the option ijob=6 for the inversion of BRF data in various view directions. - Updated the manual, new version is 04.2013. [6.12.2012] November, December 2012: - Introduced elliptical LAD for foliage orientation in tree crowns. - Replaced two-layer homogeneous CR model ACRM by its modification ACRMf. - As a result of these modifications, the format of input files changed. - The manual is updated to the Version-12.2012 - frtman1212.pdf [3.08.2009] July, August 2009: - Fixed errors in diffuse fluxes in JQSRT(71:1-9), diffor.f and dif3.f. Added approximate expressions of scattering operators for conservative layer, layer.f. - Updated the manual, new version is 08.2009. [10.08.2007] August 2007: - Updated the manual, new version is 08.2007. [23.05.2006] May 2006: - Some modifications of the calculation of diffuse fluxes in subroutines dif3() and diffor() - A read directive in the main program (frt.f) handled unix and DOS format input files differently [29.04.2005] April 2005: - The stem shape is accounted for using tapering curve by Ozolins, 1988. - In the calculation of gap probabilities the displacement of stems is random (a Poisson pattern). - An uninitialized array in the module funcf.f fixed. - Modifications to fit the needs of the gfortran (Fortran95) compiler, tested with gfortran-4.0.0/gcc-4.0.0 [28.03.2003] January 2003: - Replaced the cubature for the ellipsoidal crown, cubell(5) -> cubell9 [10.10.2002] September 2002: - The Verhoef's scheme from the SAIL model modified by A. Kuusk (Kuusk, 2001, J.Q.S.R.T., 71(1):1-9) is applied for the calculation of diffuse fluxes. - Some fixes in the calculation of downward radiances under canopy. August 2002: - 3D-integrals calculated using cubatures, the model turned about 20 times faster, biases in the 3D integral values decreased. [28.02.2002] February 2002: - The 2-layer homogeneous canopy model (Kuusk, 2001, J.Q.S.R.T., 71(1):1-9) for the understorey layer reflectance - two options for the leaf optics model both for the tree layer and understorey vegetation. NB! The LIBERTY model has problems - NaN-s at some wavelengths. - Modified the PROSPECT and LIBERTY models, up to 10 leaf components are possible. [12.12.2001] Detsember 2001: - Error messages changed. - Some bugfixes. [25.05.2001] May 2001: - Replaced the PROSPECT model to new one, PROSPECT-1997. [23.04.2001] April 2001: - Changed the merit function, now accounts for the expert estimate of parameter values, and for the variance of measured reflectance values. [11.12.2000] December 2000: - Three programs (ifrt, frtspec, frtad) are merged to one single program frt (forest reflectance and transmittance) which can be run both in direct and inverse modes. The structure of the input files is changed significantly: biochemistry concentrations are expressed as percent of dry matter SLW (specific leaf weight, g/m^2) November 2000: - Downward radiances added. [13.03.2000] March 2000: - Several bugfixes: hot-spot correction for the single scattering from soil in MCRM, uninitialized variables. [14.10.1999] September 1999: - The hot-spot parameter is given for every tree class separately in input files. The structure of the input files changed. August 1999: - Builded a parallel version of the model (direct mode only) for the PVM environment, tested on a Linux cluster with g77 compiler. [15.10.1998] October 1998: - Albedo of ground vegetation is calculated with 1D integration in the plain phi=90,270°. [04.08.1998] - Separate programs for angular distribution, reflectance spectrum, and inversion. [24.07.1998] July 1998: - Added single scattering from stems. - Changed the number of free parameters in the inversion. May 1998: - The model works for any view direction. - The same code works both in direct and inverse modes. - Changes in the calculation of the bidirectional gap probability pooi (accounting for stems changed, crown shadows replaced by circles). [04.05.1998] March 1998: - The gap probability of the tree layer is calculated with binomial model. - Effective LAI with Chen's formula in the block of multiple scattering. - The homogeneous model MCRM (Kuusk, Agricult. Forest Meteorol., 1995, 76(3-4): 221-236) is used for the ground layer vegetation. - Regressions are used for the calculation of missing crown parameters. [04.03.1997] March 1996: - Reflectance of ground vegetation is tabulated in an input file. - Soil reflectance is calculated with Price' vectors. - Incorporated leaf optics model PROSPECT. - replaced the exchange of parameters via common to formal parameters of subroutines and functions October 1995: - 6S modules for the calculation of the diffuse/total ratio of incoming fluxes. August 1995: - diffuse/total ratio of the incoming radiation as an input parameter for the model. - Both the reflected and transmitted radiances can be used in inversion. December 1994: - Unix version of the model. Changed the model to more modular, exchange of parameters via common-s, separated structure and optics modules. Both direct and inverse versions of the model. (Andres Kuusk) [1988] - DOS version of the forest reflectance model by Tiit Nilson & Anne Jõeveer. Nadir reflectance for a single wavelength.