Middle atmospheric electrodynamics: status and future

Middle atmospheric electrodynamics is a field stimulated by the recent discovery that large electric fields may occasionally exist in the mesosphere and upper stratosphere. The measurements suggest V m⁻¹ magnitudes for these fields, which have been reported to occur in both horizontal and vertical configurations. Since they are usually confined within bounded height regions, they might be of local origin. Although the measurements are still considered controversial, the implications of such fields, if real, could be important. Should these fields persist in both space and time, they could perturb the global electric circuit with a component subject to modulation by phenomena related to solar activity. This might help explain the numerous correlations which exist for tropospheric electrical response to solar and geomagnetic activity. Further work is now required to validate the earlier findings and determine the morphology and extent of the large electric fields. Experiments must also be derived and conducted to determine the physical origin of such fields and their relationships to external influences, such as magnetospheric electric fields and tropospheric thunderstorms. The current status of results regarding V m⁻¹ fields in the middle atmosphere is reviewed in perspective with the more widely accepted electric field structure established for this region from balloon and rocket data. Other factors such as ion conductivity, ion mobility and aerosols are also considered for their potential influence on the middle atmospheric electrical environment.