The influence of the solar wind electric and magnetic fields on the latitude and temporal variations of the current density, JZ, of the global electric circuit, with relevance to weather and climate

Abstract

Observations have shown small day-to-day stratiform cloud opacity and atmospheric dynamical responses to variations in the ionosphere-earth current density (J_Z). We model the day-to-day and seasonal/bi-decadal changes in the area-integrals of ionospheric potential (V_i) near the magnetic poles due to solar wind electric field inputs. The overhead value of V_i, divided by the local column resistance (R) determines J_Z, where the conductivity of the column is the result of ionization by galactic cosmic rays (GCRs) and solar and magnetospheric energetic particle precipitation. These vary with time, due to varying solar wind magnetic field inputs, not only on the day-to-day timescale (e.g., Forbush decreases) but also on the decadal and bi-decadal and century timescales. The GCR and energetic particle inputs vary with latitude, due to filtering of particle energies in the geomagnetic field. We compare area-integrals of the amplitude of the J_Z variations due to V_i changes to those due to the R changes, for evaluating their global effectiveness in affecting cloud microphysics and weather and climate changes. The day-to-day and bi-decadal correlated weather and climate variations indicate J_Z rather than other solar forcings as mainly responsible for the correlations. The decadal and longer climate responses to space weather are not large; however, understanding them could help improve predictions of future climate change due to greenhouse gases.