On Saturday, 28 February 2015 18:04:31 UTC, General wrote:
"Alastair" wrote in message

but this map shows the current state of sea ice in the Antarctic.
http://polar.ncep.noaa.gov/seaice/sh.html

I guess that's a different representation of the same thing

The mass you mention is an island of sea ice that has formed during the SH
summer melt.

That's pretty odd though isn't it? Perhaps not, but it just seems unlikely.

I think it is unusual, but that's normal! There is less sea ice than the median in the Ross Sea, but more in the Weddel Sea.

How big is that 'island' - the size of Tasmania or something - difficult to
get a sense of scale? It's not like it's just a big iceberg. And how/why has
it calved off like that rather than melting from the ocean edge? That's what
caught my curiosity.

You can see on your map that there are other areas of sea ice which have melted next to the coast rather than from the outer edge.

If you run the animate on the page I linked you can see that it melted first on the edge of the ice shelf then on the coast at each end.

Yes, the ice shelf is mapped as part of the Antarctic land mass. Sea ice is
a few feet thick and reforms each year. Ice shelves are about 1000 feet or
more thick.

OK, that makes some sense. But I'd have preferred to see the landmass still
outlined separately from the shelves.

It is on this map.
http://nsidc.org/data/seaice_index/i...tent_hires.png

One might expect the Antarctic continent to be surrounded by sea-ice stretching out to a line of latitude in winter and withdrawing to another higher line of latitude in summer. But Earth Science is not like that. Moreover, over recent years the Arctic sea ice has got less while the Antarctic sea ice has increased. But as I said that mainly applies only in the Weddel Sea.

We live in interesting times!