Arctic-ENSO Teleconnections

The Arctic is warming at a rate three times the global average—a phenomenon known as Arctic amplification. Simultaneously, extreme weather events are becoming more frequent across the Northern Hemisphere. This study aims to analyze the link between melting arctic sea-ice, El Nino-Southern Oscillation (ENSO), and extreme weather in North America. ENSO’s effect on weather is well documented. However, the role melting sea-ice plays when combined with ENSO in affecting North American weather has not yet been extensively studied. In addition,there are two distinct types of El Nino that influence weather in different ways: Eastern Pacific(EP) El Nino and Central Pacific (CP) El Nino, where the CP type has increased in frequency during recent years. To investigate the teleconnection, this study analyzed four factors for each type of El Nino in three locations: tropospheric zonal wind speed, 2 meter air temperature, geopotential, and sea level pressure over the North Atlantic Ocean, over the North Pacific Ocean, as well as over the continental United States and Canada between 1950-2020. The four factors were analyzed by comparing the average distribution pattern found in the case years to the distribution found in climatology. The study found that for each of the analyzed factors, low amounts of sea ice produce distribution patterns similar to those found during El Nino, but that when El Nino is present it dominates. Additionally, analysis of geopotential indicates higher pressure over the northeast extended to the southwest during CP Nino, implying drier conditions; during EP Nino, there is lower pressure over the west and south, implying wetter conditions. Greater understanding of the teleconnections between arctic sea-ice, ENSO, and mid-latitude extreme weather is increasingly important in helping societies improve weather prediction and preparation.