Investigating how El Niño affects precipitation in the Antarctic Peninsula and West Antarctica

Rainfall in West Antarctica, especially around the Antarctic Peninsula, shows great variability on the interannual time scale. In recent years, scientific research activities, tourism and fishing have experienced remarkable growth there. Therefore, understanding the variability of rainfall in West Antarctica, including the Antarctic Peninsula, is of great importance for both scientific and practical aspects.

As the strongest signal of interannual climate variability, El Niño has a significant impact on the Antarctic climate, especially in the West Antarctic.

However, a recent study showed that the effect of ENSO (which stands for El Niño–Southern Oscillation and refers to a wider climate pattern that includes the phases of El Niño and La Niña) on the precipitation in West Antarctica is not significant, which is not consistent with its significant effect on the West Antarctic climate through the modulation of the Amundby wave system in the sea that forms the Amundby Sea low pressure sea or Rosssen Sea. s rotation).

In a paper recently published in Atmospheric and Oceanic Science LettersProf. Shuanglin Li from the Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China, and Xueyang Chen and Dr. Chao Zhang from the China University of Geosciences, Wuhan, China, explains the effects of different types of El Niño rainfall events over West Antarctica and the Antarctic Peninsula, and explains the uncertain connection between the two.

“Previous studies have shown that precipitation in West Antarctica, especially the Antarctic Peninsula, is less connected to El Niño. One possible reason is that these studies do not classify El Niño into two known sub-types: EP [Eastern Pacific] and CP [Central Pacific] El Niño,” explained Prof. Li.

EP and CP events have the same effect on precipitation in the Amundsen–Bellingshausen ocean, but opposite effects in the Weddell Sea, including the eastern Antarctic Peninsula, thus canceling each other out in terms of the precipitation response they induce. Of course, this accounts for the uncertainty of ENSO’s influences on Antarctic Peninsula rainfall.

“The EP events forced two branches of Rossby wave trains that propagated southeast and converged in West Antarctica, which caused an anomalous anticyclone and cyclone over the Ross–Amundsen–Bellingshausen ocean and the Weddell Sea, respectively.

“In comparison, only a weak and westward-shifted Rossby wave train is activated under a CP event, which induces an anomalous anticyclone and cyclone in the Ross–Amundsen sea and Bellingshausen–Weddell sea. Anomalous southerly winds reduce precipitation over the Amundsen–Bellingshausen in the northern sea, while Wedcipillion winds in the northern sea increase precipitation over the sea. Chen.