Geophysical Research Letters (2016) https://doi.org/10.1002/2015GL067443
S. Viscardy, F. Daerden, and L. Neary
Simulations with a general circulation model for the atmosphere of Mars show that surface emissions of methane can result in a highly nonuniform vertical distribution throughout the atmosphere, including the formation of layers, during the first weeks after the release. The fate of the released methane is determined by the global circulation pattern at the time of the release, and the methane can be transported to locations over the planet that are remote from the emission site. It typically takes several weeks for the methane to become more uniformly mixed, implying that the detection of vertical layers of methane can be indicative of recent surface emission. This puts the existing observations in a new perspective and will allow instruments on the upcoming ExoMars Trace Gas Orbiter mission to detect signatures of surface emission activity as they are designed to measure the first vertical profiles of methane on Mars.
The animation above shows the simulation of a plume of methane released from Nili Fossae just before the northern hemisphere autumn (around Ls = 150). After around 10 Martian days (or sols), the plume has encircled the globe and formed a layer at around 20 km height. After 20 sols, the methane is dispersing but a layer is still visible above 40 km.
