Near-surface atmospheric water vapor enhancement at the Mars Phoenix lander site

We used Phoenix Surface Stereo Imager data, constrained by other Phoenix and MRO data taken via a planned coordinated measurement campaign, along with radiative transfer modeling to assess the vertical water vapor profile at the Phoenix arctic location during its spring and summer mission. We examined 16 mid-afternoon observations spanning Ls=97.5º – 148º. We developed a 2-layer model of vapor distribution which reproduces the water vapor band depth. Using the results of the 2-layer model, we retrieved the mass mixing ratios in each layer and the implied surface vapor pressure. We found that near surface water vapor was enhanced relative to higher layers, resulting in a large percentage of the water column (>25% and up to nearly 100%) confined below ~2.5 km.