## 3 Results
### Spatial-Temporal Patterns of Standardized Anomalies of Drought Indices during the 2019 Drought  
To reflect the intensity of the drought process in the MLRYR, the average Tem and accumulated PPT among all meteorological stations from August to November in the past 60 years were analyzed. As shown in Figure 6a, the Tem exhibited a significant upward trend (0.017 \({}^{\circ}\)C a\({}^{-1}\), \(p<0.05\)), with a significant downward trend before 1990 and a significant upward trend after that. In 2019, the Tem reached 21.91 \({}^{\circ}\)C, slightly higher than in 1998--the highest in the past 60 years. In addition, unlike Tem, PPT generally showed a nonsignificant fluctuation upward trend (0.647 mm\(\cdot\)a\({}^{-1}\), \(p>0.05\)) during 1961-2020; however, in 2019, PPT was only 229.5 mm, slightly lower than 1966, with the lowest in the past 60 years (Figure 6b). High Tem and less PPT led to this typical continuous drought in 2019 summer and autumn in this region. Figure 4: Temporal variations of annual mean MODIS GPP and GOSIF, NDVI, EVI, and NIRv (**a**) and their linear fit (**b–e**) during 2000–2020. Figure 5: Temporal variations of monthly mean MODIS GPP and GOSIF, NDVI, EVI, NIRv (**a**) and their polynomial fit (**b–e**) during 2000–2020. Note: \(N\) indicates the data size. To further reveal the intensity and scope of the 2019 drought event process, seven drought indexes, namely PPT, SM\({}_{\text{surf}}\), SM\({}_{\text{root}}\), SPEI, Tem, LST, and PAR, were selected for this research. Moreover, in order to explore the drought process more specifically, we extended the study period by one month, namely from July to December 2019. The spatial-temporal characteristics of standardized anomalies of each index from July to December 2019 are analyzed in Figure 7. As shown in Figure 7, except for July, PPT in other months of 2019 was all below the averages during 2011-2020. From July to September, the monthly average of PPT showed a significant downward trend in 2019. It reached a low point in September (33.1 mm), where the difference between the monthly average of 2019 and that during 2011-2020 was the largest (79.1 mm). Then, the PPT increased slightly in October and reached its lowest point in November (26.6 mm). After that, the PPT increased steadily and was close to the average level during 2011-2020 in December (46.7 mm). In Figure 7, the SM\({}_{\text{surf}}\) and SM\({}_{\text{root}}\) presented similar variation characteristics. The soil moisture was slightly higher than the average in July, then exhibited a significant decreasing trend and reached the lowest point in November (0.287 m\({}^{3}\cdot\)m\({}^{-3}\)). The difference between the monthly average of 2019 and that during 2011-2020 was the largest (0.078 m\({}^{3}\cdot\)m\({}^{-3}\)). After that, the soil moisture increased somewhat in December, especially in the SM\({}_{\text{surf}}\). As shown in Table 1, a similar phenomenon can also be detected from SPEI in Figure 7, especially from September to December; the SPEI values were lower than 0.5 and reached the lowest in November (\(-1.66\)). Contrary to other variables, as can be seen in Figure 7,f, the Tem and LST in July of 2019 were both below the multi-year average during 2011-2020; however, the Tem and LST are significantly higher than the multi-year average in other months. Similar change characteristics could also be found in PAR except for October, while in October, the PAR in 2019 is virtually indistinguishable from the 2011-2020 average (Figure 7). Figure 8 presents the standardized anomalies of PPT, SM\({}_{\text{surf}}\), SM\({}_{\text{root}}\), SPEI, Tem, LST, and PAR spatially. The standardized anomaly of SPEI showed a similar variation characteristic as that on the temporal scale (Figure 7). During July-August, the negative SPEI standardized anomalies were mainly distributed in the northern part of MLRYR, namely HB, AH, and JS provinces. From September to November, the negative standardized anomalies of SPEI gradually expanded from north to south and almost the entire area.