Tianshan topographic heating and a Central Asian dipole precipitation anomaly in the mid-Holocene

The manner in which the climate over arid central Asia (ACA) changes in a warming world is an important issue. Due to the region’s complex terrains, most climate models do not perform well in the area. Here, we utilize high-resolution (~50 km) and PMIP4 simulations to assess the mid-Holocene precipitation changes over the ACA. The results show that only 4 of the 15 models have captured the basic precipitation seasonality over the summer-precipitation-dominated sub-region. Among them, only the high-resolution CESM and the IPSL-CM6A-LR have successfully simulated the summer precipitation dipole. A significant increase occurs in the Tarim Basin, while a decrease takes place across the regions north of the Tianshan Mountains, which is consistent with multi-proxy records. The northern drying is primarily linked to the adjusted wave trains along the weakened mid-latitude westerlies. In contrast, the southern moisture stems from enhanced monsoon penetration into the Tarim Basin, driven by the enhanced Tianshan heat source. This monsoon intrusion in models depends significantly on the strengthened Tianshan heating; thus, the Tianshan heat source is a key factor in shaping the regional hydroclimate, which should be taken seriously in climate models.