Inter‐model spreading of changes in East Asian winter monsoon circulation under 1.5 and 2.0°C global warming targets

Abstract

AbstractThis study investigates inter‐model spreading of changes in East Asian winter monsoon circulation and the underlying reasons under 1.5 and 2.0°C global warming for Representative Concentration Pathway 8.5. Results show that the spatial patterns of multi‐model ensemble and inter‐model spreading of changes in 850‐hPa zonal and meridional winds over East Asia are similar under the two global warming targets. The multi‐model ensemble changes in 850‐hPa meridional wind (V850) over southern China are near zero under the two targets. Meanwhile, the V850 changes over southern China exhibit large inter‐model spreading, which is closely related to those of regional differences in sea surface temperature changes (DSSTC) in the tropical Pacific. Models with positive V850 anomalies over southern China tend to project weak (strong) surface warming in the western North Pacific (South China Sea and the equatorial central and eastern Pacific). Such a configuration results in decreased precipitation over the east of the Philippines and hence an anomalous lower‐level high to its northwest. Accordingly, southwesterly anomalies prevail over southern China. The southwesterly anomalies are further enhanced by related positive feedback processes. Models with negative V850 anomalies tend to project strong (weak) surface warming in the western North Pacific (South China Sea). The projected surface warming in the equatorial central and eastern Pacific is also strong, but weaker than that of models with positive V850 anomalies. Therefore, the induced precipitation and circulation changes over the East Asia–western North Pacific are basically opposite to those described above. Besides, the inter‐model spreading of V850 changes over southern China decrease by about 36.2% from 1.5 to 2.0°C global warming, which can be partly attributed to the decrease in the inter‐model spreading of DSSTC in the tropical Pacific. Numerical experiments confirm the role of the sea surface temperature changes in the tropical Pacific.