# Estimating the Fractional Vegetation Cover from GLASS Leaf Area Index Product
## 3 Methodology  
### Calculation of FCover  
In this study, the estimation of FCover is based on the measures of the transmittance of light through the canopy considering the vegetation elements as opaque. As light passes downward through the top of a canopy, the fraction of the light transmitted through the canopy can be approximated using an exponential model [33]:  
\[P_{\mathrm{tr}}\left(\varphi\right)=e^{-\sqrt{a}\times k_{\mathrm{c}}\left( \varphi\right)\times\Omega\times lai} \tag{1}\] \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline
**Site Name** & **Lat (\({}^{\circ}\))** & **Lon (\({}^{\circ}\))** & **Biome Type** & **Year** & **DOY** & \
\begin{tabular}{c} **Mean** \\ **Fcover** \\ \end{tabular} &
\begin{tabular}{c} **Uncertainties** \\ **of FCover** \\ \end{tabular} \\ \hline Alpilles2 & 43.8103 & 4.7146 & Broadleaf crops & 2002 & 204 & 0.349 & 0.264 \\ Barrax & 39.0569 & \(-\)2.1041 & Broadleaf crops & 2003 & 193 & 0.236 & 0.294 \\ Cameron & \(-\)32.5983 & 116.2542 & Broadleaf forests & 2004 & 63 & 0.414 & 0.079 \\ Chilbolton & 51.1640 & \(-\)1.4306 & Broadleaf crops & 2006 & 166 & 0.647 & 0.192 \\ Counami & 53.471 & \(-\)53.2377 & Broadleaf forests & 2001 & 269 & 0.838 & 0.030 \\  & & & 2002 & 286 & 0.858 & 0.003 \\ Demmin & 53.8921 & 13.2071 & Broadleaf crops & 2004 & 164 & 0.586 & 0.215 \\ Donga & 9.7701 & 1.7783 & Grasses and cereal crops & 2005 & 172 & 0.423 & 0.161 \\ Fundulea & 44.4061 & 26.5830 & Broadleaf crops & 2001 & 128 & 0.341 & 0.203 \\  & & & 2002 & 144 & 0.374 & 0.263 \\  & & & 2003 & 144 & 0.319 & 0.192 \\ Gilching & 48.0818 & 11.3204 & Broadleaf crops & 2002 & 199 & 0.676 & 0.214 \\ Gnangara & \(-\)31.5338 & 115.8823 & Broadleaf forests & 2004 & 61 & 0.221 & 0.035 \\ Gourma & 15.3247 & \(-\)1.5546 & Grasses and cereal crops & 2000 & 244 & 0.236 & \\  & & & 2001 & 275 & 0.126 & & \\ Haouz & 31.6592 & \(-\)7.6002 & Broadleaf crops & 2003 & 71 & 0.248 & 0.182 \\ Hirsikangas & 62.6438 & 27.0114 & Needleaf forests & 2003 & 226 & 0.644 & 0.201 \\  & & & 2004 & 190 & 0.537 & 0.234 \\  & & & 2005 & 159 & 0.442 & 0.210 \\ Hombori & 15.3309 & \(-\)1.4750 & Savannah & 2002 & 242 & 0.2 & \\ Hyytiala & 61.8513 & 24.3076 & Needleaf forests & 2008 & 188 & 0.461 & 0.223 \\ Jarveselja & 58.2987 & 27.2622 & Needleaf forests & 2000 & 188 & 0.705 & 0.169 \\  & & & & 2001 & 165 & 0.783 & 0.141 \\  & & & & 2002 & 178 & 0.793 & 0.108 \\  & & & & 2003 & 208 & 0.803 & 0.142 \\  & & & & 2005 & 180 & 0.842 & 0.118 \\  & & & & 2007 & 112 & 0.535 & 0.295 \\  & & & & 2007 & 199 & 0.731 & 0.189 \\ Laprida & \(-\)36.9904 & \(-\)60.5526 & Grasses and cereal crops & 2001 & 311 & 0.722 & 0.117 \\  & & & 2002 & 292 & 0.534 & 0.049 \\ Larose & 45.3804 & \(-\)75.2170 & Needleaf forests & 2003 & 219 & 0.847 & 0.156 \\ Larzac & 43.9375 & 3.1229 & Grasses and cereal crops & 2002 & 183 & 0.3 & 0.065 \\ Nezer & 44.5679 & \(-\)1.0382 & Needleaf forests & 2000 & 211 & 0.499 & 0.149 \\  & & & & 2001 & 99 & 0.363 & 0.193 \\  & & & & 2001 & 175 & 0.785 & 0.194 \\  & & & & 2002 & 107 & 0.304 & 0.136 \\ Plan-de-Dieu & 44.1986 & 4.9481 & Broadleaf crops & 2004 & 189 & 0.172 & 0.130 \\ Puechabon & 43.7245 & 3.6519 & Broadleaf forest & 2001 & 164 & 0.54 & 0.157 \\ Rovaniemi & 66.4556 & 25.3514 & Needleaf forests & 2004 & 161 & 0.423 & 0.137 \\  & & & 2005 & 166 & 0.497 & 0.182 \\ Sonian & 50.7681 & 4.4110 & Needleaf forests & 2004 & 174 & 0.903 & 0.028 \\ Sud\_Oueset & 43.5062 & 1.2375 & Broadleaf crops & 2002 & 189 & 0.352 & 0.219 \\ Turco & \(-\)18.2350 & \(-\)68.1836 & Shrubs & 2001 & 208 & 0.106 & 0.026 \\  & & & 2002 & 240 & 0.02 & 0.013 \\  & & & 2003 & 105 & 0.044 & 0.011 \\ Wankama & 13.6449 & 2.6353 & Savannah & 2005 & 174 & 0.036 & 0.035 \\ Zhang\_Bei & 41.2787 & 114.6877 & Grasses and cereal crops & 2002 & 221 & 0.353 & 0.143 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Characteristics of the 28 validation sites.