Relating Jovian Lightning Rates and Water Abundance: a One-Dimensional Model

Direct observations of Jupiter's deep atmospheric water abundance, an important constraint on its structure and the evolution of the solar system, have not thus far been conclusive. However, Jovian lightning has been observed by every Jupiter mission, and appears to have a deeper origin than the ammonia clouds. Under the generally accepted assumption that this lightning is generated in the water cloud deck, it should be possible to use lightning rates as a proxy for estimating water abundance. Given the uncertainties in the mechanics of lightning generation, such a proxy cannot give a precise value of water abundance, but can offer useful constraint. We consider a computationally light one-dimensional model of a rising plume with particle growth and non-inductive charging and show its applicability in Earth conditions; then, we examine the implications for Jupiter's atmosphere. We find strong dependence on flash rates and depth profiles on water abundance, with temperature greatly affecting depth profiles but not total rates. We then discuss the implications of observed flash rates for water abundance in Jupiter's atmosphere.