The key role of background sea surface temperature over the cold tongue in asymmetric responses of the Arctic stratosphere to El Niño–Southern Oscillation

• Published in: Environmental Research Letters
• Main Authors: Fei Xie, Xin Zhou, Jianping Li, Cheng Sun, Juan Feng, Xuan Ma
• Format: Article in Journal/Newspaper
• Language: English
• Published: IOP Publishing 2018
• Subjects: asymmetric responses; Arctic stratosphere; ENSO; background sea surface temperature; cold tongue; Environmental technology. Sanitary engineering; TD1-1066; Environmental sciences; GE1-350; Science; Q; Physics; QC1-999; Arctic; Pacific
• Online Access: https://doi.org/10.1088/1748-9326/aae79b; https://doaj.org/article/08bac17191144b768c4cbbe9a64a5294

The response of the Arctic stratosphere to El Niño activity is strong but the response to La Niña activity is relatively weak. The asymmetric responses of Arctic stratosphere to El Niño and La Niña events are thought to be caused by asymmetric El Niño–Southern Oscillation (ENSO) teleconnections. Here, we suggest that the background sea surface temperature (SST) over cold tongue of tropical eastern Pacific may be an important contributor to the asymmetric ENSO teleconnections. The atmosphere is very sensitive to tropical SST variations in the range of 26 °C–30 °C. During El Niño events, the background SST over cold tongue plus El Niño SST anomalies typically falls into the range. Under these conditions, the atmospheric response to El Niño SST anomalies is strong. During La Niña events, the background SST plus La Niña SST anomalies is typically below the range, which leads to a weak response of the atmosphere to SST anomalies. The proposed mechanism is well supported by simulations.