The Role of the Tropically Excited Arctic Warming Mechanism on the Warm Arctic Cold Continent Surface Air Temperature Trend Pattern

The December–February surface air temperature (SAT) trend is examined for all consecutive 20-year time periods between 1979 and 2017, from which a transition from a cold-Arctic-warm-continent toward a warm-Arctic-cold-continent trend pattern is evident. This transition is accompanied by a consistent transition in the sea level pressure trend pattern that supports warm air advection over the Arctic and cold air advection over the continents. The regression of the detrended December–February-average SAT onto a detrended index defined to quantify the east-west gradient of tropical Pacific sea surface temperature is characterized by a warm-Arctic-cold-continent pattern much like the SAT trend pattern observed in recent decades. A decadal timescale warming of the western tropical Pacific water has increased the east-west gradient of tropical Pacific sea surface temperature, thus contributing to the observed extratropical SAT trend transition.