## 4 Results
As shown in Figure 3b, the vegetation was still yellow in the 12 th 8-day interval and started to green up in the 15 th 8-day interval, which basically coincided with the SOS in DOY 105-140 in [PERSON] et al. [60]. Similar evaluations of estimates of SOS and EOS were implemented at other sites. Specifically, the EVI_HGAM was the appropriate model to extract SOS and EOS at US-Ho1, US-Ha1, US-MMS, US-Ne2, and US-Twt, GCC_HGAM was suitable for US-Myb, and EVI_DLF performed better than other models in US-Var (Supplementary Materials, Figure S2.1-S2.21). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Site\_ID** & **Year** & **NDVI\_HGAM** & **EVI\_HGAM** & **GCC\_HGAM** & **NDVI\_DLF** & **EVI\_DLF** & **GCC\_DLF** \\ \hline \multirow{4}{*}{US-Ho1} & \multirow{4}{*}{2013} & 16.86 & 17.58 & 14.42 & 17.46 & 18.97 & 9.57 \\  & & (36.86) & (32.67) & (39.06) & (18.46) & (29.41) & (15.01) \\  & & (6.72) & 17.31 & 15.77 & 0.07 & 19.91 & \(-\)12.13 \\  & & (45.55) & (31.72) & (38.25) & (3.90) & (28.09) & (16.17) \\  & & 17.80 & 18.75 & 15.32 & 17.85 & 19.21 & 5.31 \\  & & (44.56) & (32.22) & (38.52) & (39.06) & (32.08) & (13.90) \\  & & 14.02 & 17.17 & 14.92 & 14.52 & 16.67 & \(-\)12.01 \\  & & (43.61) & (34.78) & (34.83) & (35.12) & (35.18) & (14.12) \\  & & 14.69 & 17.58 & 15.98 & 16.16 & 17.39 & \(-\)48.10 \\  & & (37.85) & (34.47) & (36.42) & (32.59) & (34.55) & (16.51) \\  & & 2012 & 15.64 & 17.53 & 15.95 & 16.59 & 17.41 & \(-\)15.79 \\  & & (38.61) & (34.33) & (34.87) & (34.91) & (34.38) & (15.37) \\  & & 15.32 & 15.95 & 10.68 & 14.80 & 15.06 & \(-\)63.56 \\  & & (36.68) & (34.96) & (35.73) & (36.70) & (35.39) & (10.56) \\  & & 14.74 & 16.23 & 13.12 & 15.54 & 15.05 & 11.17 \\  & & (37.85) & (34.69) & (37.76) & (41.16) & (35.28) & (232.91) \\  & & 14.65 & 16.72 & 14.78 & 15.24 & 15.74 & \(-\)60.81 \\  & & (38.25) & (35.10) & (36.59) & (37.29) & (35.61) & (14.74) \\  & & 2010 & 21.32 & 22.08 & / & 20.41 & 23.21 & / \\ US-Ne2 & & (34.33) & (32.98) & / & (34.51) & (29.20) & / \\  & & 19.83 & 21.14 & / & 7.97 & 22.60 & / \\  & & (33.66) & (32.04) & / & (18.55) & (27.96) & \\  & & 21.27 & 21.95 & / & 21.74 & 21.86 & / \\  & & (44.06) & (32.26) & / & (32.89) & (30.69) & \\  & & 22.40 & 22.89 & 23.61 & 23.95 & 22.89 & 25.36 \\ US-Twt & & (37.98) & (37.13) & (37.94) & (37.31) & (37.23) & (31.73) \\  & & 21.90 & 21.81 & 16.99 & 23.32 & 21.18 & 20.52 \\  & & (38.12) & (37.17) & (31.32) & (37.01) & (36.68) & (28.36) \\  & & 18.88 & 16.72 & 19.38 & 20.65 & 16.94 & 22.60 \\  & & (37.94) & (37.62) & (32.22) & (32.71) & (36.94) & (29.71) \\  & & 2012 & 12.44 & 13.03 & 11.14 & \(-\)1.39 & 13.33 & 11.70 \\ US-Myb & & (43.43) & (42.13) & (42.26) & (8.39) & (40.47) & (50.75) \\  & & 13.12 & 13.48 & 16.09 & \(-\)0.53 & 13.56 & \(-\)11.49 \\  & & (41.95) & (41.81) & (43.43) & (1.13) & (40.20) & (13.33) \\  & & 11.00 & 13.12 & 12.17 & 11.52 & 14.16 & \(-\)12.58 \\  & & (36.50) & (35.68) & (29.69) & (45.13) & (34.77) & (13.76) \\  & & 2012 & 6.27 & 6.81 & 8.97 & 19.45 & 8.07 & \(-\)15.74 \\  & & (18.61) & (18.79) & (18.03) & (21.74) & (18.35) & (15.22) \\ US-Var & & 7.17 & 7.76 & 4.33 & 9.71 & 8.85 & \(-\)12.19 \\  & & (17.71) & (17.67) & (16.72) & (16.97) & (17.32) & (13.12) \\  & & 1.72 & 4.83 & 7.62 & \(-\)1.31 & 6.25 & 12.34 \\  & & (17.31) & (16.77) & (17.13) & (10.81) & (16.17) & (16.25) \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Key phenological stages (SOS and EOS (number within parenthesis)) extracted by HGAM and DLF at the seven flux tower sites.