Investigating a link between solar wind variability and atmospheric dynamics in polar regions

Abstract

<p>Evidence are pointing to two potential links between solar wind forcing and atmospheric dynamics in polar regions. The chemical link follows from energetic particle precipitation (EPP) ionizing the higher atmosphere, leading to a production of nitrogen and hydrogen oxides (NOx and HOx), which later on participate in ozone destruction. This can lead to changes in the radiative balance of the atmosphere, followed by related changes in winds. The physical link is related to the interplanetary magnetic field (IMF) and its ability to modulate the global electric circuit (GEC), with a hypothesized link between changes in the GEC and polar tropospheric dynamics through cloud generation processes. By use of ERA-5 reanalysis data and OMNI near Earth solar wind magnetic field and plasma parameter data, we investigate these links with a multiple correlation analysis. Internal atmospheric variability is excluded before the analysis. Time period of the data is 1979-2018. Results concerning the chemical link show a significant negative correlation between EPP (geomagnetic activity index Ap used as a proxy) and pressure anomalies in the local winter inside the polar vortex. The anomaly, starting in the stratosphere, extends downwards to the surface in a matter of days. The results indicate a greater response in the north compared to the south. For the physical link, a significant correlation is seen between the IMF horizontal (By) component and lower tropospheric pressure in the south for certain months in local summer. There seems to be no correlation between the two indices, Ap and By, indicating that these mechanisms operate individually without aliasing between the two. These results imply that solar wind variability can potentially impact polar atmospheric dynamics during specific seasons in different ways. This can enhance our understanding on solar related atmospheric effects.</p>