Atmospheric Co2 Depletion Near The Surface In The
Martian Polar Regions
S. Piqueux, Jet Propulsion Laboratory, California Institute Of Technology, Pasadena, Usa (Sylvain.Piqueux@Jpl.Caltech.Edu), P.O. Hayne, Department Of Astrophysical And Planetary Sciences And Laboratory For Atmospheric And Space Physics, University Of Colorado Boulder, Boulder, Co, Usa, A. Kleinböhl, D.M. Kass, M. Schreier,
Jet Propulsion Laboratory, California Institute Of Technology, Pasadena, Usa, D.J. Mccleese, J.T. Schofield, Jet Propulsion Laboratory, Retired, J.H. Shirley, Jet Propulsion Laboratory, Retired, Now Torquefx Llc, N. Heavens, Space
Science Institute, Boulder, Co, Usa, M.I. Richardson, Aeolis Research, Chandler, Az, Usa.

Introduction: The Yearly Waxing And Waning Of
The Seasonal Polar Caps Represents One Of The Most
Dramatic Expressions Of The Co2 Cycle On Mars, With
Massive Amounts Of Carbon Dioxide Cyclically Exchanged Between The Atmosphere And The Surface [1].
As Co2 Condenses On The Surface, Non-Condensable
(Nc) Species (Ar, N2, Co, Etc.) Are Left Behind And
Accumulate In The Atmosphere, Resulting In A Decrease
Of The Co2 Partial Pressure Pco2 And Thus A Reduction
Of The Co2 Frost Point Temperature Tco2 [2].
Throughout The Exploration Of Mars, Infrared Brightness Temperatures Of The Seasonal Caps As Low As ~ 13
K Below Tco2 Have Been Observed. These “Cold
Spots” Were Attributed, At Least In Part, To Enrichment
In Non-Condensable Gases [2-5], Although Clouds
[3,6], Snowfall [3,7], And Small Low Emissivity Ice