Observations of water vapour and carbon monoxide in the Martian atmosphere with the SWC of PFS/MEX

► The mean concentrations of H2O and CO are about 9.6 pr. μm and 990 ppm, respectively. ► H2O and CO concentrations show a strong seasonal variations at high latitudes. ► The seasonal water vapour map reproduces the known seasonal water cycle. ► H2O and CO respond in opposite way to polar caps condensing/sublimating processes. ► The seasonal variation of CO concentration depends on the surface pressure.