## 3 Results
### Correlation Analysis between ET and Driving Factors
#### 3.2.4 Correlation Analysis between Specific Humidity and ET  
The correlation coefficient between ET and SH ranged from \(-\)0.92 to 0.89 at the annual scale, and the spatial average correlation coefficient was \(-\)0.15, which meant the correlation between ET and SH was more often negative (Figure 12a). As shown in Figure 12b, it could be seen that the area of regions with significant and extremely significant positive correlation between ET and SH was 10.15%, of which 6.27% was an extremely significant positive correlation, which was concentrated in the middle and upper reaches of the YRB. The areas with significant and extremely significant negative correlation accounted for 26.09% of the total area of the basin, of which the area of extremely significant negative correlation was 14.67%, mainly distributed in the middle and lower reaches of the YRB and sub-basin C, and the areas with non-significant correlation between ET and SH was relatively large, accounting for 63.76% of the total area of the YRB.  
Figure 10: Spatial distribution map (**a**) and significance test results (**b**) of correlation coefficient between SR and ET at the annual scale in the YRB. A\(-\)M represent 13 sub-basins of the YRB, which are as follows: the Jinsha River Basin; the mountainous areas in the upper reaches of Dadu River and Jialing River; the confluence area of Sichuan Basin; the main stream area in the upper\(-\)middle reaches of the Yangtze River; the Wujiang River Basin; the middle reaches of the Yangtze River; the confluence area of Nanyang Basin; the Jianghan\(-\)Dongting Lake Plain; the Dongting Lake Basin; the mountainous area of Ganjiang River Basin; the Poyang Lake Plain; the confluence area of Chao Lake and the plain along Wanjiang River; and the confluence area of the Yangtze River Delta.  
Figure 11: Correlation significance test results of monthly SR and ET in the YRB. A\(-\)M represent 13 sub-basins of the YRB, which are as follows: the Jinsha River Basin; the mountainous areas in the upper reaches of Dadu River and Jialing River; the confluence area of Sichuan Basin; the main stream area in the upper\(-\)middle reaches of the Yangtze River; the Wujiang River Basin; the middle reaches of the Yangtze River; the confluence area of Nanyang Basin; the Jianghan\(-\)Dongting Lake Plain; the Dongting Lake Basin; the mountainous area of Ganjiang River Basin; the Poyang Lake Plain; the confluence area of Chao Lake and the plain along Wanjiang River; and the confluence area of the Yangtze River Delta.  
Similarly, the heterogeneity of the correlation between ET and SH for the 12 months in the YRB was significant (Figure 13). Fewer regions showed a significant positive correlation between SH and ET, with the highest percentage of 19.08% in March. From February to October (except July), the regions with positive correlation were mainly distributed in the middle and upper reaches of the YRB. From July, November, to January of the next year, the regions with positive correlation were mainly distributed in the middle and lower reaches of the YRB. However, the regions where SH and ET were negatively correlated were almost absent from January to April and concentrated in the middle and upper reaches of the YRB from May to September and in the middle and lower reaches of the YRB from October to December. At the same time, it could be observed that there was very little negative correlation between the two in the headwaters of the YRB. In summary, the correlation between the two did not show obvious cyclical change.