Simulated Influence of the Atlantic Multidecadal Oscillation on Summer Eurasian Nonuniform Warming since the Mid-1990s
Based on ensemble experiments with three atmospheric general circulation models (AGCMs), this study investigates the role of the Atlantic Multidecadal Oscillation (AMO) in shaping the summer nonuniform warming over the Eurasian continent since the mid-1990s. The results validate that the positive-phase AMO can indeed cause nonuniform warming, with predominant amplified warming over Europe-West Asia and Northeast Asia, but with much weaker warming over Central Asia. The underlying mechanism is then diagnosed from the perspective that the boundary forcing modulates the intrinsic atmospheric variability. The results highlight the role of the Silk Road Pattern (SRP), an intrinsic teleconnection pattern across the subtropical Eurasian continent propagating along the Asian jet. The SRP can not only be identified from the AGCM control experiments with the climatological sea surface temperature (SST), but can also be simulated by the AMO-related SST anomaly (SSTA) forcing. Furthermore, diagnostic linear baroclinic model experiments are conducted, and the results suggest that the SRP can be triggered by the AMO-related tropical diabatic heating. The AMO-triggered SRP-like responses feature anticyclonic circulations over Europe-West Asia and Northeast Asia, but cyclonic circulation over Central Asia. These responses cause increased warm advection towards Europe-West Asia and Northeast Asia, reduced precipitation and cloud cover, and then increased downward shortwave radiation. This increased warm advection and increased downward shortwave radiation together cause amplified warming in Europe-West Asia and Northeast Asia. The situation is opposite for Central Asia.
KeywordsAtlantic Multidecadal Oscillation nonuniform warming Silk Road Pattern
本文基于三个大气环流模式(AGCMs)的集合试验, 探究了北大西洋多年代际振荡(AMO)在1990s中期后欧亚大陆夏季不均匀增暖中的作用. 结果表明正位相AMO会造成不均匀增暖, 具体表现为欧洲-西亚和东北亚增暖较强, 中亚增暖较弱. 从边界强迫调节大气内部变率的角度进一步诊断AMO的影响机制. 研究结果强调了丝绸之路波列(SRP)的重要作用, 该波列是沿亚洲急流传播的, 跨副热带欧亚大陆的大气遥相关型. SRP不仅能在气候态海温(SST)强迫的AGCM参照试验中识别, 还可以被AMO海温异常强迫试验模拟. 此外, 线性斜压模式的试验结果表明, 与AMO有关的热带非绝热加热异常同样会激发SRP. AMO激发的类SRP响应在欧洲-西亚和东北亚地区是反气旋环流, 在中亚地区是气旋环流. 该环流型造成欧洲-西亚和东北亚暖平流加强, 降水和云覆盖率减少, 向下的短波辐射增加. 加强的暖平流和向下的短波辐射共同导致欧洲-西亚和东北亚增暖加强. 中亚情况相反.
关键词北大西洋多年代际振荡(AMO) 不均匀增暖 丝绸之路波列(SRP)
Unable to display preview. Download preview PDF.
This work was supported by the National Key Research and Development Program of Ministry of Science and Technology of China (Grant 2018YFA0606403 and 2015CB453202).
- Chen, M., P. Xie, J. E. Janowiak, and P. A. Arkin, 2004: Verifying the reanalysis and climate models outputs using a 56-year data set of reconstructed global precipitation. Proc. 14th AMS Conference on Applied Meteorology, Washington, Amer. Meteor. Soc.Google Scholar
- Hong, X. W., R. Y. Lu, and S. L. Li, 2017: Amplified summer warming in Europe-West Asia and Northeast Asia after the mid-1990s. Environmental Research Letters, 12, 094007, https://doi.org/10.1088/1748-9326/aa7909.
- Jin, F. F., and B. J. Hoskins, 1995: The direct response to tropical heating in a baroclinic atmosphere. J. Atmos. Sci., 52, 307–319, https://doi.org/10.1175/1520-0469(1995)052<0307:TDRTTH>2.0.CO;2.CrossRefGoogle Scholar
- Kalnay, E., and Coauthors, 1996: The NCEP/NCAR 40-year reanalysis project. Bull. Amer. Meteor. Soc., 77(3), 437–472, https://doi.org/10.1175/1520-0477(1996)077<0437:TNYRP>2.0.CO;2.CrossRefGoogle Scholar
- Peng, S. L., and J. S. Whitaker, 1999: Mechanisms determining the atmospheric response to midlatitude SST anomalies. J. Climate, 12, 1393–1408, https://doi.org/10.1175/1520-0442(1999)012<1393:MDTART>2.0.CO;2.CrossRefGoogle Scholar
- Ting, M. F., and S. L. Peng, 1995: Dynamics of the early and middle winter atmospheric responses to the northwest Atlantic SST anomalies. J. Climate, 8, 2239–2254, https://doi.org/10.1175/1520-0442(1995)008<2239:DOTEAM>2.0.CO;2.CrossRefGoogle Scholar
- Wang, Y. M., S. L. Li, and D. H. Luo, 2009: Seasonal response of Asian monsoonal climate to the Atlantic multidecadal oscillation. J. Geophys. Res., 114, D02112, https://doi.org/10.1029/2008JD010929.Google Scholar
- Yanai, M., S. Esbensen, and J. H. Chu, 1973: Determination of bulk properties of tropical cloud clusters from large-scale heat and moisture budgets. J. Atmos. Sci., 30, 611–627, https://doi.org/10.1175/1520-0469(1973)030<0611:DOBPOT>2.0.CO;2.CrossRefGoogle Scholar