**4.7. Effects of KRD on atmospheric circulation**

The modified water and energy budget due to Karst rocky desertification was the first-order effects. Because of the different input of heat and moisture into atmospheric circulation, the large-scale circulation features were altered, resulting in climatic effects beyond the desertification area. As shown in **Figure 14**, the weakened 3-month mean wind vector at 700 hPa

**Figure 14.** Ensemble mean differences in JJA wind vector (m/s) at 700 hPa between Case D and Case C.

between Case D and Case C was caused by the lower surface heating in GKP (**Figure 13d**). The monsoon airflow from the Bay of Bengal, an important moisture source for the East Asia, was weakened from the degraded areas to the northeast. Furthermore, the weakened southwest airflow had significant impacts on the East Asian monsoon, especially, the anomaly cyclone (**Figure 14**) and the stronger horizontal convergence in the southeastern coastal area that led to the strengthened vertical ascending motion and the increase in precipitation.

On the other hand, the longitude-height section of the composite difference of zonal circulation along 24°–30°N between Case D and Case C was plotted to conduct further analysis (**Figure 15**). After the land degradation in GKP, an anomalous descending motion appeared in both the upper and middle level of troposphere over GKP and the middle and lower troposphere of the adjacent regions to the east. Such circulation modification caused the strengthened ascending motion over 114°–122°E. Moreover, the stronger lifting over the coastal areas led to the increase in the vertically integrated moisture flux convergence (VIMFC) from 1000 to 300 hPa. Consequently, the different circulation and moisture flux reduced the rainfall over GKP and promoted the formation of clouds and the positive rainfall anomalies over southeastern coastal areas of China (**Figure 12a**). Also, in the southeast China, the surface cooling (**Figure 12b**) was induced by the increased amount of clouds and further a negative net cloud radiation forcing.

**Figure 15.** Zonal-height cross sections of ensemble mean differences in JJA zonal (ms−1) and vertical (10–2 ms−1) winds averaged over 24°–30°N. Gray shading indicates topography.
