Long-term studies of ozone and water vapour in the atmosphere of Mars could lead to better understanding of atmospheric chemistry for the Earth. A new analysis of data from ESA's Mars Express mission has revealed that our knowledge of the way these atmospheric gases interact with each other is incomplete.

Using four martian years of observations from the SPICAM (Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars) instrument, which corresponds to seven and a half Earth years, a team of researchers from Europe and Russia uncovered the gap in our knowledge when trying to reproduce their data with a global climate model of Mars.

Ozone and water vapour do not make good atmospheric companions. On Mars, since the carbon dioxide is ubiquitous, there should be a global signature of ozone – unless a particular region contains water vapour.

Thus, wherever SPICAM detected water vapour, it should have seen a decrease in ozone. The more water vapour, the less ozone. The team investigated this inverse relationship, also known as an anticorrelation. They found that they could reproduce the general inverse nature of it with a climate model but not achieve the precise relationship. Instead, for a given amount of water vapour, the model produced only 50% of the ozone seen in the SPICAM data.

More details here.

Image credit: ESA