Historical and projected relationships between the Tibetan Plateau summer monsoon and precipitation in Central Asia based on multi-CMIP6 models

Abstract

Based on the historical and SSP1–2.6, SSP2–4.5 and SSP5–8.5 experiments from20 Coupled Model Inter-comparison Project phase 6 (CMIP6) models, the historical and projected relationships between the Tibetan Plateau summer monsoon (TPSM) and precipitation in Central Asia (CA) are investigated. The historical experiments show that the CMIP6 models have large uncertainties in simulating the relationships between the TPSM and the Central Asian precipitation and their corresponding dynamic processes. 60% (12) of the CMIP6 models can simulate the close positive correlation between the TPSM and the precipitation in the key region (37°-45°N, 65°-85°E) of CA, but only 8 of them can capture the dynamic processes linked the TPSM and the precipitation in CA during 1971–2010. So we select the 8 models out of the 20 based on their skills in capturing the dynamical processes as observed. Regression analysis shows that the 8 selected models will still simulate the positive correlation between the TPSM and the precipitation in CA and capture their linked dynamic progresses during the second half of 21st century (2050–2099), but with the rising of emission scenarios, the significant area of correlations will gradually shrink. During 2050–2099, 75% of the 8 selected models suggest the TPSM will strengthen, especially in northern monsoon regions, corresponding to significant increase of summer precipitation in the key region (37°–45°N, 65°–85°E) of CA in SSP1–2.6 and SSP2–4.5 experiments. In SSP5–8.5 experiment, 6 out of the 8 selected models also indicate the TPSM will strengthen in the northern monsoon region, corresponding to significant increase of precipitation in most of key region and decrease in eastern key region.