Space weather influences on atmospheric electricity

This paper summarises the various mechanisms by which space weather is thought to affect atmospheric electricity on Earth. These include: ionisation changes from GCRs and SEPs that affect the vertical conductivity profile; interactions between the solar wind and magnetosphere generating horizontal ionospheric electric fields that couple down to the surface; changes in ionospheric conductivity due to precipitating electrons; lightning generation from energetic particles. Although this discussion has separated mechanisms into those that affect conductivity or the ionospheric potential, in reality most space-weather events are a complicated superposition of both of these effects. This means that although evidence of a space weather influence on atmospheric electrical parameters exists (e.g. Harrison et al., 2013b), the coupling mechanisms are not well understood. Further work is required to understand the role of changes in the 'disturbed weather', that is, thunderstorms and 'fair weather' part of the circuit, both of which are likely to contribute to changes observed in atmospheric electrical parameters. To further understand the effects of space weather on the GEC, which may in turn also influence clouds, more measurements of atmospheric electrical responses to short-term solar perturbations are required, with high temporal resolution measurements, over a wide range of geomagnetic latitudes. New developments in atmospheric technology allow in situ measurement of ionisation rates from GCRs and SEPs simultaneously with atmospheric electrical parameters (Nicoll, 2013) from standard meteorological radiosondes, facilitating new, low cost, space-weather monitoring in the troposphere and stratosphere using the existing operational radiosonde network. Such observations are important to assess the effects of atmospheric electricity on layer clouds, which provides a route by which changes in space weather may couple to lower tropospheric processes. © 2014 Royal Meteorological Society.