5 Aug 2014, Matthew Shupe [73N, 169E]

We are passing through a region where the ice is very dirty, sometimes with actual dirt, and sometimes with biology. I don’t know the details for sure, but I think a lot of the ice in this region has previously been shore fast ice, meaning that it was close to the coast and grounded on the sea-floor. Interactions with the sea-floor are one way to pull up the dirt. But I suspect there could also be dust and dirt blown by the winds from the continent out over the sea ice. Dark dirt particles absorb more sunlight than the reflective ice, leading to localized heating and some very interesting melt patterns on the dirty ice. The second kind of dirty ice is more green in appearance, sometimes spectacularly so. I think this is related to ice algae communities that live in the ice. Usually they are towards the bottom and seem to fill certain layers of the ice. However, this greenish color is not everywhere but instead occurs in pockets that are spread out randomly through the ice pack, sometimes very widely spaced. Why is there enhanced biological activity on some ice and not others? And is there any interaction between these two communities (the dirt and the algae)? So many questions remain, but it does make for more interesting ice viewing.



Green ice


Dirty ice