Response of Regional Asian Summer Monsoons to the Effect of Reduced Surface Albedo in Different Tibetan Plateau Domains in Idealized Model Experiments

The thermal effect of the entire Tibetan Plateau (TP) tends to strengthen the South Asian summer monsoon (SASM); however, how does this monsoon component respond to the thermal conditions of different TP domains? How do the thermal conditions of the entire TP influence other monsoons, including the East Asian summer monsoon (EASM) and the Southeast Asian summer monsoon (SEASM)? These questions are addressed by conducting an experiment with the CESM, which is forced by reducing the surface albedo over the plateau by half, from a TP-averaged 0.20 to 0.10, from May to September, and similar experiments for different TP domains. Both observational and model results show that the entire TP heating intensifies the large-scale Asian monsoon, the SASM, and the EASM but surprisingly weakens the SEASM. It is also surprising that the TP heating exerts a stronger effect on the EASM than on the SASM. The southern TP (south of 35 degrees N) does not show the strongest impact on the SASM in comparison with other TP domains, and it exerts the weakest impact on the EASM, which is most strongly influenced by the thermal effect of the eastern (east of 90 degrees E) and northern TP. The western TP weakens the SEASM (as do the other domains), and it strengthens other monsoon components. The thermal conditions of the southern and eastern TP are accompanied by signals of tropical atmospheric response at relatively broader spatial scales, whereas those of the northern TP more apparently lead to a significant wave train extending eastward from the TP to western Eurasia over the higher latitudes.