Quantitative evaluations of subtropical westerly jet simulations over East Asia based on multiple CMIP5 and CMIP6 GCMs

As a salient feature of the Asian monsoon system, East subtropical westerly jet (EASWJ) exerts significant impacts on weather and climate changes in China even throughout Asia. In this paper, we applied new self-adaptive algorithm to detect EASWJ, identify its boundaries, then represent characteristics by defining three indices: intensity index, meridional displacement width index. Compared reanalysis data, carried out comprehensive, objective, quantitative EASWJ evaluation using historical experiments from multiple global models (GCMs) Coupled Model Intercomparison Project Phases 5 6 (CMIP5 CMIP6). The results show that multimodel ensemble mean (MME) both CMIP5 CMIP6 can simulate winter well. While for other seasons, MME phase underestimate 200-hPa zonal wind (U200) strength coverage area overestimate U200 outside area, such simulation weaken shear field. simulations GCMs had no consistent or location characteristic tendencies, most tended relatively wide-coverage jets. contrast, are inclined significantly weaker, wider, more-northward predecessors CMIP5, about half minimized bias, but remarkable errors were still observed their representations. Furthermore, comparative analysis performed classifying based evaluated suggested simulated performance temperature gradient was important capturing characteristics. Further in-depth study causes model differences is warranted improve results.