Oren, yes, I think it is just the ice winking in and out.
There's a large region of slush around the ESS that must be at the edge of being called ice.
Some musing on measurements & definitions...
Presumably the definitions for extent and area won't be of any fundamental physical significance. Instead, there's an algorithm processing the input data & it has a threshold for whether to include each area element. Whether e.g. a region of wet slush is counted depends on the instruments and on the algorithm in a way that is not physically simple. That's fine, presuming the answer obtained is somewhat reasonable, and the answer is consistently applied for each new day. It then gives a somewhat reasonable measure for how the extent and area are progressing.
In contrast, it should be possible to define volume in a more physical way. For example, it could be defined in proportion to the weight of water (typically ice and snow) that extends above the water level for liquid water. The total volume is then obtained by summing up the weight-per-unit-area over the defined Arctic region. That gives a simple physical understanding. The measured value would of course still be an experimentally extracted approximation to that simple physical definition.
With this wonderful new satellite they are about to put up, which gives very accurate height measurements, a very simple physical definition would be a sum/integral of the heights above local sea level - then converting to a volume of ice using either a single constant for ice density or else using locally estimated densities after attempting to estimate the ice/snow/melt pond mix.
Again, that's a physically simple approach to measuring the ice volume/mass.
This is not my field though. Is that fair comment? Is that how e.g. the PIOMAS definition of volume is extracted in practice?
