## 3 Results
### Response of Drought to Changes in Temperature, Precipitation, and ET  
Figure 10 illustrates the insignificant negative correlation between TVDI and precipitation across the whole year, accounting for 63.4%, primarily observed in southern Shaanxi with higher altitudes and southeastern Yanchi County. The non-significant positive correlations with temperature and ET were 86.4% and 58%, respectively, with the absolute values of the average partial coefficients ranging from largest to smallest as follows: ET, 0.43; temperature, 0.15; and precipitation, 0.11. In spring, TVDI and temperature exhibited slightly higher mean partial correlation values (r1 = - 0.33, r2 = 0.39, r3 = 0.37) than precipitation and ET. Shenmu County, Yanchi County, and northern Dingbian County accounted for 24.6% of the significant positive correlation. In summer and autumn, TVDI mostly showed non-significant negative correlations with precipitation and non-significant positive correlations with temperature and evapotranspiration. The relative values of precipitation and TVDI in autumn ranged between \(-\)0.74 and \(-\)0.84, with a high average partial coefficient (\(-\)0.28). In winter, the mean partial correlation values between TVDI and ET were larger than those of precipitation and temperature. The correlations ranged from negative to positive to negative from west to east, with non-significant positive correlation. The correlation values of precipitation and TVDI are larger than those of precipitation and temperature. relations pre-dominating, while some areas of Wushen Banner showed highly significant positive correlations. Figures 11 and 12 depict the partial correlation values between spring precipitation and TVDI for the six land use types, primarily ranging from \(-0.44\) to \(-0.18\), with over 80% exhibiting an insignificant negative correlation. Forestland exhibited a slightly more significant negative correlation than the other five types. In summer, compared to spring, the partial correlation coefficients were considerably lower and more dispersed, indicating  
Figure 10: Spatial distribution of correlation coefficients and significance of TVDI with precipitation (**a–d**), temperature (**b–e**), and ET (**c–f**) bias in different seasons of MUSL (2001–2020). that TVDI responded more strongly to precipitation in spring than in summer. The pattern of partial correlation values in fall mirrored that of summer, except for forestland, which showed roughly an 18% significant negative correlation with building land. Winter seasons were characterized by predominantly non-significant negative correlations, with partial correlation coefficients for grassland, desert land, and unused land closer to those of summer, while all others were lower than the other three seasons. Non-significant negative correlation pre-dominated throughout the whole year, except for building land and unused land. Spring TVDI exhibited the strongest partial correlation values with temperature among the six categories, while summer desert land showed greater partial correlation values than the other five types. Correlation coefficients of different types in autumn were concentrated above 0.01, with more stable fluctuations than in summer. In winter, the correlation between different land types across seasons except grassland was minimal, with the lowest value of 0.02 observed for the correlation coefficient between grassland and temperature over the course of the year, indicating that grassland in winter and the whole year is not sensitive to temperature. Partial correlation coefficients between TVDI and ET for all land types except desert land in autumn exhibited a decrease followed by an increase throughout all seasons and the whole year, with trough and peak positions in autumn and the whole year, respectively. The whole year averaged higher correlation coefficients across various land types than the four seasons, with less variability observed among the same land use types.