I've worked out a region mask for the PIOMAS gridded data grid boxes. The data is in a flat file format, and is a sequence of bytes in the same order as the sequence of single precision numbers used in PIOMAS thickness files.
The region mask itself is available here:
https://drive.google.com/file/d/0B3pB-kdzoLU3dURtLVpJQm1ONEE/edit?usp=sharingI've plotted it, some of the rough edges (spikes) show the limitation of my plotting technique, i.e. the dots plotted for each grid point are larger than the grid boxes in the central region.
The regions are numbered as follows:
0 Non Regional Ocean
1 Sea of Okhotsk and Japan
2 Bering Sea
3 Beaufort Sea,
4 Chukchi Sea
5 East Siberian Sea
6 Laptev Sea
7 Kara Sea
8 Barents Sea
9 Greenland Sea
10 Central Arctic
11 Canadian Arctic Archipelago
12 Baffin Bay/Newfoundland Sea
13 Hudson Bay
14 Gulf Of St Lawrence
15 Land
All regions derived from the region graphic on the Crysophere Today main page (which is an NSIDC format 25km grid), land derived from the PIOMAS landmask.