01 November 2008

Happy 30th to sea ice

A belated happy 30th birthday to our continuous* record of sea ice coverage from satellite! 26 October 1978 is the first data from the SMMR instrument, so last weekend the record finally hit 30 years.

* Ok, not exactly continuous, there's a gap between SMMR and the first SSMI to follow. But it's only a matter of (quite a few) weeks, rather than years as happened between ESMR and SMMR.


Anonymous said...

I wonder if I might ask a couple of questions?
I asked the first question at Hot Topic and Gareth suggested that I come to you with said question.
Has there been a change of salinity in the Artic Ocean in recent years? Gareth pointed out that with less ice cover, wind and wave action would probably intermix the fresh and salt water rather well. This is something I hadn't considered but I'll let the question stand.
The other question pertains to Artic sea ice thickness. My understanding is that while 2008 didn't quite match 2007 in surface area melt, volume/thickness was much reduced. Would this reduced thickness make it easier for the East Greenland Current to push ice out of the Arctic Basin?

Robert Grumbine said...

Definitely questions are welcome. If some don't seem to be apt for a post, then use the most recent 'question place' post as a home for them.

The high Arctic upper ocean salinity is something that needs a ship to investigate. I haven't been checking the literature on this, so don't know the current status. The Arctic, though, is much more stable (making it harder to mix by wind and wave action) than most of the world's ocean. This is because of the large fresh water runoff from the Ob', Yenesei, Lena, and Mackenzie into the Arctic. Changes in river outflow might be more important than changes to ice area. Then again, maybe not. I'll have to check the observations when I get back.

Thinner ice moves more easily in response to winds and ocean currents, so yes, it's now easier to shove out of the Arctic. Or to push elsewhere. So you'll want to keep an eye on the atmospheric circulation as well.

Good questions. Thanks.