Relationship between Solar Wind−Magnetosphere Energy and Eurasian Winter Cold Events

The profound impact of solar irradiance variations on the decadal variability of Earth’s climate has been investigated by previous studies. However, it remains a challenge to quantify the energetic particle precipitation (EPP) influence on the surface climate, which is an emerging research topic. The solar wind is a source of magnetospheric EPP, and the total energy input from the solar wind into Earth’s magnetosphere (E_in) shows remarkable interdecadal and interannual variability. Based on the new E_in index, this study reveals a significant interannual relationship between the annual mean E_in and Eurasian cold extremes in the subsequent winter. Less frequent cold events are observed over Eurasia (primarily north of 50°N) following the higher-than-normal E_in activity in the previous year, accompanied by more frequent cold events over northern Africa, and vice versa. This response pattern shows great resemblance to the first empirical orthogonal function of the variability of cold extremes over Eurasia, with a spatial correlation coefficient of 0.79. The pronounced intensification of the positive North Atlantic Oscillation events and poleward shift of the North Atlantic storm track associated with the anomalously higher E_in favor the anomalous extreme atmospheric circulation events, and thus less frequent extreme cold temperatures over northern Eurasia on the interannual time scale. It is further hypothesized that the wave−mean flow interaction in the stratosphere and troposphere is favorable for the connection of E_in signals to tropospheric circulation and climate in the following winter.