Projected change in the relationship between East Asian summer rainfall and upper-tropospheric westerly jet

Abstract

The authors analyzed the interannual variability in summer precipitation and the East Asian upper-tropospheric jet (EAJ) over East Asia under the Historical and Representative Concentration Pathways Scenarios (RCPs, including RCP4.5 and RCP8.5), using outputs of 17 Coupled Model Intercomparison Project phase 5 (CMIP5) coupled models. The analyzed results indicate that the models can reasonably reproduce relatively stronger interannual variability in both East Asian summer rainfall (EASR) and EAJ. These models can also capture the relationship between the rainfall anomaly along the East Asian rain belt and meridional displacement of the EAJ. Projected results suggest that the interannual variabilities in precipitation along the East Asian rain belt and in the EAJ are enhanced under the scenarios RCP4.5 and RCP8.5 in the 21st century, which is consistent with the previous studies. Furthermore, it is found that the relationship between the East Asian rainfall and the meridional displacement of the EAJ is projected to be stronger in the 21st century under the global warming scenarios, although there are appreciable discrepancies among the models. East Asian summer monsoon has an important social and economic impact in eastern China, the Korean Peninsula and the southern and central Japan. Its variability causes serious floods and droughts, which are the most natural disasters in East Asia, and brings about great damages in this region. The interannual variability in East Asian summer rainfall (EASR) is closely related to the frequency of floods and droughts. Therefore, the interannual variability in rainfall can be approximately used as an important index to measure the possible changes in the frequency of floods and droughts under global warming scenarios. Many projected results suggested that East Asian summer precipitation will increase in the context of global warming [1][2][3][4][5]. Some other studies indicated that the interannual variability in EASR will be enhanced in the future [6,7], corresponding to the increase of precipitation. On the other hand, Lu and Fu [7] showed that the interanuual variability in EASR is intensified much more remarkably in comparison with summer precipitation itself in East Asia under the global warming scenarios, implying more frequent occurrence of droughts and floods in the future.The EASR is closely related to the East Asian uppertropospheric westerly jet (EAJ). As an important component of the atmospheric circulations at the upper troposphere and low stratosphere in the mid latitudes, the EAJ exhibits a unique feature [8,9], and variations in both the location and intensity of the EAJ play a crucial role in influencing weather and climate in East Asia [10][11][12]. On the interannual timescale, the meridional displacement of the EAJ is the most prominent feature in summer [13] and it is intimately related to the EASR. A southward (northward) displaced EAJ is associated with increased (decreased) EASR

Evaluation of the subtropical westerly jet and its effects on the projected summer rainfall over central Asia using multi‐CMIP5 models

“…Zhang and Guo () suggest that the summer SWJ will strengthen and migrate southwards over eastern Asia in the future under the warming background scenario. Dai and Lu () point out that the relationship between the East Asian rainfall and the meridional displacement of the East Asian Jet is projected to be stronger in the 21st century under the different global warming scenarios. Sea surface temperature (SST) warming is a prominent feature of global warming.…”

Meridional position biases of East Asian subtropical jet stream in CMIP5 models and their relationship with ocean model resolutions

“…Following Guo et al (), Huang and Liu () revealed that the climatological mean state of the EASJ, including its intensity, location and seasonal evolution, is well portrayed in the AM2.1, a model developed at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL). Dai and Lu () investigated the temporal‐spatial features of East Asia summer rainfall and the EASJ in 17 models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) and found that the models capture the interannual variability of rainfall in East Asia and Northwest Pacific and that of the EASJ; the correlation between the precipitation anomaly and the meridional displacement of the EASJ is also reproduced.…”

Inter‐model Spread of the Changes in the East Asian Summer Monsoon System in CMIP5/6 Models

“…Based on the projections of CMIP5 models, Horinouchi et al (2019) suggested that the climatological changes of the EAJ show a weakly southward shift. In addition, Dai and Lu (2012) suggested that the relationship between the inter-annual variabilities in EASM rainfall and EAJ becomes stronger under global warming.…”