Weak El Ni?o and Winter Climate in the Mid-to High Latitudes of Eurasia
According to the sca surfacc temperature anomaly(SSTA)intensity in the Ni?o-3.4 region and the cast-west gradient across the Pacific.three types of El Ni?o are identified in this work.An event with larger than average intensity is defiined as a strong El Ni?o.all others are considered to be weak events.Almost all strong El Ni?os are concurrent wiih a large gradient.which is fcatured by negative SSTAs in the western Pacific and positive SSTAs in the cquatorial castern Pacific(EP)and Indian Occan(IO).According to the cast-west gradieni,the weak events can be subdivided into gradient-weak(GW)El Ni?o and equatorial-weak(EW)El Ni?o.The GW El Ni?o characterizes a great east-west gradient without a significant IO SSTA.In contrast.the EW event fcatures a positive SSTA over the tropical IO and EP.The impact of GW El Ni?o on the North Atlantic-Eurasia continent(NA-Eurasia)displays a negative North Atlantic Oscillation(NAO)-like at-mospheric anomaly.resulting in a drier and cooler-than-normal winter over Eurasia.Observational and numerical evidence indicate that the prolonged subtropical jet from the North Pacific to NA acts as a wvaveguide that captures the planetary Rossby waves gencrated by the GW El Ni?o.This wvaveguide favors the propagation of the perturbations into the downstrcam regions.which would affect the NA-Eurasian climcte.However.the EW El Ni?o is accompanied by a relatively weak subtropical jet that cannot impact the NA-Eurasian climate significantly.For the strong El Ni?o,the absence of the NAO signal can be attributed to the counteracting of the teleconnections triggered by the Pacific and the tropical IO.
PENG ZHANG BIN WANG ZHIWEI WU
Deparment of Atmospheric and Oceanic Sciences & Institute of Armospheric Sciences,Fudan University,S Earth System Modeling Center,Nanjing University of Informtion Science and Technology,Nanjing,China,a Department of Atmospheric and Ocenic Sciences & Insititite of Atmospheric Sciences,Fudan University,
国内会议
厦门
英文
4-20
2019-06-01（万方平台首次上网日期，不代表论文的发表时间）