Mars Inversion moisture trap, insulation power keeping water from escaping to space

~ESA great capture of trapped in a crater ice infers a lot of water on Mars
~The trap is a cooled atmospheric interface,   much similar to what sea ice does
~No sea ice,  none or far weaker inversions,  less sea ice possible as a result

ESA composite picture of a Mars North Pole crater called Korolev,  has amazingly similar sea ice features on Earth, likely there is snow as well.  But the greatest feature,  the reason why there is frozen water  in the North Polar Martian region,  is exactly the same as the over abundance of ice near Earth Poles:  inversions.   Remove the inversion,  and massive sublimation occurs,  because there is an inversion,  the moisture in air is trapped within a shallow layer,  reducing the possibility of sublimation especially if the atmosphere is near 100% saturated with water vapor.    Korolev crater gives the impression that there is a great deal of water in Martian underground.   But this moisture has very little chance of staying within an atmosphere 95% CO2.   We can see here something equally similar to the disappearance of glaciers on Earths polar regions:

We can see here evidence of recently evaporated/sublimated smaller snow glaciers by the lighter soil colors,   Mars soil is mainly oxidized red,  suggesting rust,  small glaciers remove contact with the atmosphere, after time they likely strip the top rust by small calving process,  but once the small glacier evaporates/sublimates,  it leaves behind its imprint.  Arctic rock strewn lands having small glaciers exhibit exactly the same feature,  except Arctic small glaciers are disappearing very rapidly,  they leave behind a lighter rock surface color for much shorter time periods ,  unlike Mars .13% oxygen content,  Earth's atmosphere is rich in  Oxygen.    Further evidence of snow on top of ice can be seen here:

        Snow or ice crystal drifts can be seen in this ESA's Mars Express topographic image.
Within the thin inversion ice crystals likely fall back to the surface and sublimate upwards in an endless process similarly within a closed climatic system,  over a long period of time falling ice crystals may gather high insulating the ice further.   WD December 25, 2018

Mars InSight landing spot photos suggest not so deep permafrost

~Atmospheric refraction of a CO2 atmosphere is probably visible,  more dedicated photos are required though.
~First photographic hints at very slight horizon refraction
~Given the thinness of the atmosphere, much of this of course was expected,  but further very serious photography should be undertaken.

    Mars has a 6 mb atmosphere,  169 times less weighty than on Earth.  Not many refraction specialists believe it capable of causing some atmospheric mirages,  but near the horizon,  the game changes, at that level,  we look at a much thicker atmosphere.  Consider what we always knew,  Mars landscape looked carved by water ever since a closer telescopic look at the planet was achieved.   Now that we have access to a probe capable of staying still,  by refraction optics we can see if there is any ice permafrost,  which can give a spectacular effect similar to sea ice horizons on Earth.

     Ice and Martian soil should have different specific heat capacity,  ice has most certainly  a greater heat capacity, which means that it affects the soil right over it,  in particular,   when the cloudless sunny sky  hits a pure rocky outcrop,  the air right above warms up rapidly,  this may cause a "road mirage"  like on Earth,  however subtle likely so on Mars, but none heard of so far.   Examples here show no rapid lowering,  a sure sign of a permeating factor.  Here we study the Martian horizon,  by NASA design from a probe not moving around all over the place:

NASA InSight December 5 and 7 2018 .  15:27  and at 11:34 local mean solar time respectively,  the 5th has greater shadow to the right.  The robotic arm has likely moved around, and is placed back not always exactly  in this same resting spot.   The pictures are aligned,  with your mouse pointer, verify carefully the positions of nearest rocks,  now look at the horizon.  Point your mouse at any point on the horizon line,  you will see the darker image having a very slightly higher horizon throughout.  The darker image is nearest local noon, with warmest sun effects,  was likely taken with an optical filter.  If there is near surface permafrost the horizon should eventually lower,  in this case the horizon lowered perhaps further and is now rising towards the near noon height, meaning the ground horizon has sea ice properties,  namely frozen water....

  Experience on Earth dictates:  top of sea ice warms enough to lower the horizon after local apparent noon, given no great weather change,   this usually happens a few hours after noon.  The brighter image here is at 3:27 PM usually at about the same time when the sea ice horizon reaches lower point on Polar Earth.

     CO2 Martian atmosphere may cause different refraction effects,  namely 95% CO2 concentration surely gives a great  warming potential,  so the surface should warm really rapidly when the sun rises, again a dry rocky substratum horizon should lower at local apparent noon,  not take a few hours as on Earth.  Which as we know,   on any given sunny day without much great weather circulation,  noon is not the warmest time of day.

   A rudimentary model using refraction index of CO2 gas,  incidentally greater than air at standard pressures and temperatures,  calculates a very small shrinking of the vertical sun disk equally at  the horizon.  However,  the interplay between Martian soil, permafrost and CO2 atmosphere is novel,  more studying is needed.  WD December 9 2018