Historical and projected relationships between the dominant modes of summer subtropical westerly jet and precipitation over Central Asia based on CMIP6 models

Based on historical and the SSP5-8.5 experiments from twenty Coupled Model Intercomparison Project 6 (CMIP6) models, the historical and projected relationships between the summer dominant modes of the subtropical westerly jet (SWJ, 20-55 degrees N, 40-80 degrees E) and the corresponding precipitation over Central Asia (CA) are investigated. The historical experiment shows that almost all (19) CMIP6 models except for the EC-Earth3-Veg model can simulate the changes in summer dominant modes of the SWJ, and sixteen of them can reproduce the relationships between the summer dominant modes of the SWJ and precipitation over CA as observed. Changes in the dominant modes of the SWJ correspond to the formation of anomalous cyclones in different parts of CA, which play important roles in modulating the summer precipitation over CA, and only ten of the sixteen models can capture the above physical progress. The dominant modes of the SWJ in the ten selected models retain unchanged and they are still closely related to summer precipitation over CA in the SSP5-8.5 experiment in the second half of the twenty-first century. Nine (seven) of the ten models agree that when the SWJ moves southward (strengthens), the domain of 37-47 degrees N, 60-85 degrees E (47-55 degrees N, 55-75 degrees E) will receive more summer precipitation in the SSP5-8.5 experiment during 2050-2099. Large uncertainties exist in the projected change in the strength of the SWJ and summer precipitation over CA among the nine unselected models during 2050-2099.