Towards predicting lightning and TLE’s in exoplanetary atmospheres

Electrical processes such as lightning and transient luminous events (TLEs) are important drivers of chemical processes in planetary atmospheres, including potentially facilitating the formation of important prebiotic molecules. The numerous extrasolar planets discovered present a huge diversity in environmental conditions to explore the possible emergence of electrical processes. To this end, we adapt general circulation models to simulate these exoplanet atmospheres and study the potential emergence of electrical processes. Here, we present results from simulations of tidally locked rocky exoplanets with the Met Office Unified Model. Lightning parameterisations that use bulk cloud properties - such as cloud-top height, frozen water content, and graupel flux - are initially used to infer lightning flash rates. For tidally locked exoplanets, we find that lightning is limited to the permanent dayside hemisphere, with substantial spatial and temporal variations. We then discuss methods to determine the charge structure and thus electric field strengths in the atmospheres, that can be used to infer whether lightning flashes can be followed by TLEs. Finally, we put the electrical processes into context of the atmospheric chemistry and potential observational consequences.