Thursday, May 19, 2016

Optically unlikely not possible remote sensing/model? measurements/calculations

     85 to 90 N NOAA Reanalysis.  May 16, 2016.  Use the mouse pointer to compare surface and top of sea ice temperatures.

     There are several reasons why surface sea ice temperature can't be warmer than surface air. #1  It is optically not observable,  if there is a steep adiabatic profile from ground/ice  temperature to Surface air 2 meters above,  it would give an optical illusion,  similar to hot road mirages.   We have here on this example given many locations with a 2 degree C temperature difference between skin to surface air.  This would give a   lapse rate 100 times more than the normal 10 C/Km.     #2 Thermally improbable.  Top of sea ice temperature influences the surface air temperature,  if the air is colder than top of sea ice,  this is a very unstable thermal structure,  ice would cool rapidly by convection upwards of the air touching it.  While air warmer than sea ice invokes a normal stable thermal structure.    Because ice/snow surface is white,  especially since thermal conduction from lower in the column sea ice is much greater than air to top of ice, air conduction affects top of sea ice less than colder sea ice column core minima,  very necessarily  at this time of late spring.  #3 clouds.  Likely covering 85N to the Pole here,  clouds offer a more neutral thermal flux balance,  whereas there is a steady equal heat flux up and down at the surface to air interface.  The net result is more of an isotherm,  but still slightly favoring the stable thermal structure,  which is colder top of sea ice than surface air.  WD May  19, 2016

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