Surface melt indicators

The graph above is based on pixel-counting on the images of the "sea ice thickness and melt ice concentration" product on the JAXA ADS VISHOP website.  The graph shows the number of non-melting (i.e., non-blue) ice pixels in those images.  Note that blue ice pixels may indicate either surface melting of the ice (a wet surface) or a low ice concentration (i.e., large amounts of open water between the ice floes).  The data start on 3 July 2012.

SMOS (and SMAP) satellite measurements are used during the freezing season to measure the thickness of thin sea ice of less than 50 centimeters thick.   In summer, the data becomes highly unreliable for sea ice thickness since it is heavily affected by surface melting on the ice (and melting of the snow layer on top of the ice) as soon as temperatures get above the melting point.  Roughly speaking, the measurements get more strongly affected when surface melting is stronger, and so it gives indirect information about the strength of the surface melt.  The data are also strongly affected by sea ice concentration, especially in the last part of the melt season.

The graph above is calculated using pixel counting on the SMOS/SMAP images on the Uni Bremen website.  (In fact, these calculations have been refactored in the meantime to use the Bremen numeric data files instead of the images).   Low values in the graphs would correspond to more wetness on the sea ice (and/or lower sea ice concentration) and hence stronger surface melt.  The algorithm interpolates missing data from nearby pixels.

The graphs below are only updated during the Antarctic melt season (December to February).