## 5 Results  
### Statistical Evaluation of the GPP Datasets  
None of the GPP product data follow a normal distribution across the study regions. The time series of MODIS GPP for all regions, and histograms related to these time series, are shared in Figure S3. The average GPP values for Antalya, Erzincan, Izmir, Kirklareli, Konya, Samsun, and Sanliurfa are 2.53, 1.29, 2.51, 2.52, 0.97, 3.27, and 1 g C m\({}^{-2}\) d\({}^{-1}\), respectively. The lowest GPP value, 0 g C m\({}^{-2}\) d\({}^{-1}\), was found in the Erzincan region, while the highest GPP value, 8.72 g C m\({}^{-2}\) d\({}^{-1}\), was observed in the Samsun region. The time series of MuSyQ GPP for all regions, and histograms associated with these time series, are presented in Figure S4. The average GPP values from MuSyQ were as follows: Antalya 2.04, Erzincan 1.13, Izmir 3.43, Kirklareli 2.51, Konya 0.68, Samsun 3.00, and Sanliurfa 1.05 g C m\({}^{-2}\) d\({}^{-1}\). The lowest GPP value was 0.03, observed in the Erzincan region, while the highest GPP value was 8.23 g C m\({}^{-2}\) d\({}^{-1}\), which was observed in the Samsun region. Distribution graphs and time series graphs for the study areas are presented in Figure S5. The lowest GPP estimates from the PMLV2 were 0.11 g C m\({}^{-2}\) d\({}^{-1}\) and 0.33 g C m\({}^{-2}\) d\({}^{-1}\), recorded in the regions of Erzincan and Konya, respectively, while the maximum GPP values recorded were between 7.27 g C m\({}^{-2}\) d\({}^{-1}\) and 9.04 g C m\({}^{-2}\) d\({}^{-1}\), observed in the Antalya and Samsun regions, respectively (Figure S5). Recent years have seen notably high values in the Antalya, Erzincan, Izmir, and Konya regions; the increase in the frequency of high values in recent years can be observed from the time series graphs (Figure S6). In the TL-LUE GPP datasets, the highest values were detected at 11.93 g C m\({}^{-2}\) d\({}^{-1}\) in Samsun and 8.51 g C m\({}^{-2}\) d\({}^{-1}\) in Kirklareli. The lowest GPP from GOSIF values were identified in Erzincan, while the highest were observed in Samsun (Figure S7). Similar to MuSyQ GPP values, almost all of the GOSIF GPP values also exhibited a distribution that was heavily right-skewed (e.g., Figure 5). The lowest values from FLUXCOM occurred in Erzincan, while the highest values were identified in Samsun. The FLUXCOM GPP average values for Antalya, Erzincan, Izmir, Kirklareli, Konya, Samsun, and Sanliurfa were 2.49, 1.34, 3.39, 2.07, 0.85, 2.79, and 1.31 g C m\({}^{-2}\) d\({}^{-1}\), respectively (Figure S8). Figure 4: Flowchart of the study. Figure 5: Correlation matrices of GPP datasets from the (**a**) Antalya, (**b**) Erzincan, (**c**) Izmir, (**d**) Kirklareli, (**e**) Konya, (**f**) Samsun, and (**g**) Sanliurfa regions. First, correlation coefficient values were calculated to determine relationships between different GPP products from each data point from different regions (Figure 5). All relationships were statistically significant, with important differences in the strength of the agreement. For instance, in the Antalya region, the highest correlation of 0.97 was observed between GOSIF and TL-LUE, while the lowest was 0.88 between MODIS and MuSyQ datasets. The scatter plots illustrate that variance tended to be lower for lower GPP values and vice versa for higher GPP values. A noticeable increase in variance can be observed between FLUXCOM and MuSyQ, and MuSyQ and GOSIF for high GPP values. In the case of the Erzincan region, the highest correlation was 0.99 between GOSIF and TL-LUE, and the lowest was 0.92 between FLUXCOM and MuSyQ datasets. Scatter diagrams for the Erzincan region indicate a relatively lower variance at low values compared to medium and high values. Regarding the Kirklareli region, the highest correlation coefficient of 0.99 was measured between GOSIF and TL-LUE, while the lowest correlation coefficient of 0.89 was observed between FLUXCOM and MuSyQ. For the Izmir region, the higher variance can be observed for medium and high values compared to lower values.