## 3 Results
### The Seasonal Dynamics of Climate, Vegetation Indices, and GPP at the Two Sugarcane Tower Sites
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Sites**} & \multicolumn{2}{c}{**The growing season**} & \multirow{2}{*}{**GPP\({}_{\text{PC}}\) (g cm\({}^{-2}\) yr\({}^{-1}\))**} & \multirow{2}{*}{**GPP\({}_{\text{VPM-Site}}\) (g cm\({}^{-2}\)yr\({}^{-1}\))**} & \multirow{2}{*}{**GPP\({}_{\text{VPM-Site}}\) (g cm\({}^{-2}\)yr\({}^{-1}\))**} & \multirow{2}{*}{**GPP\({}_{\text{VPM-Site}}\) (g cm\({}^{-2}\)yr\({}^{-1}\))**} & \multirow{2}{*}{**GPP\({}_{\text{VPM-Site}}\) (g cm\({}^{-2}\)yr\({}^{-1}\))**} \\  & **(GPP\({}_{\text{EC}}\) 21 g cm\({}^{-2}\)day\({}^{-1}\))** & & & \\ \hline \multirow{2}{*}{Brazil Site} & 2005/5/25-2006/5/17 & 4035.60 & 3968.45 & \(-\)1.67 \\ \cline{2-6}  & 2006/9/30-2007/5/17 & 2841.62 & 2868.59 & 0.95 \\ \hline \multirow{2}{*}{USA Site} & 2017/2/10-2017/12/11 \({}^{\text{a}}\) & 2200.88 & 1979.47 & \(-\)10.06 \\ \cline{2-6}  & 2017/2/10-2017/12/11 \({}^{\text{b}}\) & 2200.88 & 1976.89 & \(-\)10.17 \\ \hline \multirow{2}{*}{**Sites**} & \multicolumn{2}{c}{**The growing season**} & \multirow{2}{*}{**GPP\({}_{\text{EC}}\) (g cm\({}^{-2}\)yr\({}^{-1}\))**} & \multirow{2}{*}{**GPP\({}_{\text{VPM-Site}}\) (g cm\({}^{-2}\)yr\({}^{-1}\))**} & \multirow{2}{*}{**GPP\({}_{\text{VPM-Site}}\) (g cm\({}^{-2}\)yr\({}^{-1}\))**} & \multirow{2}{*}{**GPP\({}_{\text{VPM-Site}}\) (g cm\({}^{-2}\)yr\({}^{-1}\))**} \\  & **(GFP\({}_{\text{EC}}\) 21 g cm\({}^{-2}\)day\({}^{-1}\))** & & & \\ \hline \multirow{2}{*}{Brazil Site} & 2005/6/18-2006/5/17 & 3873.65 & 3913.04 & 1.01 \\ \cline{2-6}  & 2006/9/30-2007/5/17 & 2656.27 & 2776.70 & 4.53 \\ \hline \multirow{2}{*}{USA Site} & 2017/5/17–2017/11/25 \({}^{\text{a}}\) & 1893.16 & 1699.05 & \(-\)10.25 \\ \cline{2-6}  & 2017/5/17–2017/11/25 \({}^{\text{b}}\) & 1893.16 & 1709.79 & \(-\)9.68 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: A summary of the estimated gross primary production (GPP\({}_{\text{EC}}\)) and predicted GPP\({}_{\text{VPM-Site}}\) at the sugarcane EC tower sites in Brazil and USA during the growing season defined by GPP\({}_{\text{EC}}\) and LSWI, respectively. GPP\({}_{\text{EC}}\) represents the seasonal sum of the estimated GPP from the sugarcane EC flux tower sites; GPP\({}_{\text{VPM-Site}}\) represents the seasonal sum of the predicted GPP from the VPM model; a and b are the seasonal sum the GPP\({}_{\text{VPM-Site}}\) at the USA site when \(T_{\text{opt}}\) = 25 \({}^{\text{o}}\)C and \(T_{\text{opt}}\) = 28 \({}^{\text{o}}\)C, respectively. GPP\({}_{\text{EC}}\) represents the relative error, calculated as [(GPP\({}_{\text{VPM-Site}}\) -GPP\({}_{\text{EC}}\))/GPP\({}_{\text{EC}}\)] \(\times\) 100. Figure 8: Interannual variation in simulated daily gross primary production (GPP\({}_{\text{VPM-NCEP}}\)) (g Cm\({}^{-2}\) day\({}^{-1}\)) from the Vegetation Photosynthesis Model (VPM) model with NCEP climate data at the two sugarcane EC tower sites during 2000–2018. (**a**) Brazil site; (**b**) Louisiana, USA site. Brazil site varied from 2090 g C m\({}^{-2}\) yr\({}^{-1}\) in 2009/2010 to 3176 g C m\({}^{-2}\) yr\({}^{-1}\) in 2005/2006, which is closely related to climate variation, especially annual PAR (Figure 9a). The total GPP\({}_{\text{VPM-NCEP}}\) at the USA site ranged from 2607 g C m\({}^{-2}\) yr\({}^{-1}\) in 2011 to 3327 g C m\({}^{-2}\) yr\({}^{-1}\) in 2004.