Responses of mean and extreme precipitation in the arid Asian interior: A high-resolution modeling comparison of the mid-Holocene and 2 × CO2 climates

By utilizing a high-resolution Earth system model (CESM), we evaluate the mean and extreme precipitation changes over the arid Asian interior in a warming world, forced both by orbital insolation in the mid-Holocene and doubled CO 2 , representing the future. The simulations show a spatial heterogeneity in the changes in annual mean and extreme precipitation during the mid-Holocene, with significant increases over the Tarim Basin and the Tianshan Mountains (TBTS), but decreases in the regions to the west and north. In contrast, 2 × CO 2 forcing results in more consistent increases across the entire arid Asian interior. In both the mid-Holocene and 2 × CO 2 , the maximum increases are revealed in the southern Tarim Basin and the adjacent Kunlun Mountains. Compared to 2 × CO 2 , the magnitude of increases in the mid-Holocene is much higher. A distinct seasonal contrast emerges between the two warming scenarios. Over the TBTS, the greatest increases in both mean and extreme precipitation during the mid-Holocene occur in summer, whereas under 2 × CO 2 forcing the maximum generally shifts to winter. Spatially, both mean and extreme precipitation in the mid-Holocene summer show a clear north–south dipole, with increases across the TBTS but decreases to its north. Under 2 × CO 2 , summer changes remain spatially heterogeneous, with consistent significant increases confined mainly to the Tarim Basin. Notably, although 2 × CO 2 induces stronger warming, the resulting precipitation increases are weaker than during the mid-Holocene. 利用高分辨率地球系统模式 (CESM) , 本研究评估了轨道日射驱动的中全新世和温室气体驱动的2倍CO 2 情境下亚洲内陆干旱区平均态和极端降水的响应特征.模拟结果显示, 中全新世年平均和极端降水变化呈空间异质性特征, 塔里木盆地和天山地区 (TBTS) 显著增加, 北部和西部地区减少.相比之下, 2 × CO 2 情景下亚洲内陆干旱区整体呈增加趋势.最大增幅均出现在塔里木盆地南部及相邻的昆仑山地区, 但中全新世降水增幅更大.就TBTS季节性降水而言, 中全新世平均和极端降水增幅在夏季达到最大, 2 × CO 2 背景下则基本转移至冬季.夏季中全新世降水呈南多北少的偶极子型变化, TBTS增加而北部减少;2 × CO 2 下显著增加区域则主要局限在塔里木盆地.总体而言, 尽管2 × CO 2 导致更强的增温, 但其降水增幅却小于中全新世.