The Diverse Impacts of El Nino on Northeastern Canada and Greenland Surface Air Temperatures

El Nino is known to affect Arctic temperature. However, the robustness of the observed relationship between El Nino and Arctic temperature remains debated. Here we reexamine the impacts of El Nino on the Arctic temperature in boreal winter [December-February (DJF)] using reanalysis datasets and atmospheric model experiments. This study shows that extreme El Nino events are accompanied by significant boreal winter cooling over northeastern Canada and Greenland (NECG), while moderate eastern Pacific (MEP) El Nino events are accompanied by significant boreal winter warming in this region. For central Pacific (CP) El Nino events, a cold signal appears in NECG, but with no statistical signifi-cance. During extreme El Nino winters, a positive Pacific-North America (PNA)-like pattern is seen in the Pacific, and anomalously negative 200-hPa geopotential height (Z200) strengthening occurs over NECG, which is a response to anomalous strong wave activity originating in the tropical Pacific. El Nino-induced circulation anomalies can further induce NECG cooling via cold temperature advection and decreased downward longwave radiation. In contrast, for the MEP El Nino, the subtropical jet extends zonally from the North Pacific to the North Atlantic, which is accompanied by increased baroclinicity anomalies and favors the propagation of synoptic eddies into the Atlantic, leading to a negative North Atlantic Oscillation (NAO)-like pattern. This in turn could further enhance the positive Z200 anomalies over NECG, resulting in anomalous warming in NECG through warm temperature advection and enhanced downward longwave radiation. A series of atmospheric model experiments simulates the observed circulation changes and associated warming over NECG.