2005-11-29

Sea ice: what I do in my spare time

Fairly soon now I'm off to NZ (oh dear, my CO2 burden...) to present some sea ice work. The poster part of it is nz-hadcm3.pdf. I have a day or two left, so feel free to point out typos and gross scientific errors.

The theme of the work is upgrading the sea ice dynamics in HadCM3, which has occurred just in time for it to be replaced by HadGEM. Never mind, we learnt a lot in the process. Mostly we learnt how hard it is to force the sea ice to behave itself in a coupled model.

The poster (in theory) says it all, so I won't explain at length here: but feel free to ask questions...

14 Comments:

Anonymous Anonymous said...

You did ask...."parametrisation" should read "parameterisation".

9:26 pm  
Blogger James Annan said...

HaDGEM is old hat. HaDGEM2 is the new kid on the block :-)

9:50 pm  
Blogger crandles said...

I got as far as the second sentence ;)

Should be "This is better than..." not better that.

10:01 pm  
Blogger crandles said...

and near the end, a can has been shortened to ca.

10:13 pm  
Blogger crandles said...

Just a couple more:

In Effects on variability, you say "using the "best" run, above."

Is that meant to be below?

Also there is a "(see figure 7)". Does this mean the maps and graphs should be labeled?

10:22 pm  
Blogger Belette said...

Parametrisation: with or without the E is possible.

HadGEM1a is next, James: don't run too fast...

Chris: thanks; fixed (I'd already found the can). There are a few others too (now fixed offline). Fig 7: rats: spot the text ripped from my paper... above/below: yes. You are doing a good job: how are your proofreading rates?

10:27 pm  
Blogger EliRabett said...

Dear lord, who ever thought a stoat would take up Tom Sawyerism...

1:19 am  
Anonymous Wouter said...

Hey,

as a "already quite a long time" reader of your blog, I'm happy to see that you come to New Zealand, I'll sincerely hope that I will be able to talk to you there (you're by accident not taking the NZ flight Londen Auckland of friday afternoon?)

Wouter

7:46 am  
Blogger crandles said...

>how are your proofreading rates?

Very reasonable.... unless you count the trouble I could cause asking silly CPDN related questions like:

I think CPDN uses static sea ice and AFAICS it doesn't seem to work very well with the 'seaice depth' falling away and the 'Snow amount after slab' constantly rising. On a beta thread which I am not supposed to make public, I wrote:

"At 60 South in August, there are a few cell with neither snow nor ice- fine. There are some with over 2000 times the amount of snow as ice; I assume these have some land so this does not worry me. However the majority of the cells all have over 50 times more snow than sea ice. If the units are KG/M^2, wouldn't the snow be heavy enough to sink the ice and come into contact with the ocean. Am I correct to think the snow should then either melt or convert to ice?

Take the first cell at a latitude of 60 South in August as an example. Snow=73131 and sea ice=997. Is that plausible or nonsense?"

The thread concludes with Duncan saying "The runs look OK (even with the sea ice issue - at the moment!) so we've gone for it. "

Any comments on what is going wrong, or whether this is a serious problem for the model or not, would be appreciated.

2:56 pm  
Blogger James Annan said...

Sorry for the thread hijack but

Chris,

Can you clarify what you mean by cpdn using "static sea ice"? Is this detailed anywhere on their web site? I don't recall seeing it mentioned in the paper.

Maybe it is just a terminological inexactitude? We used a standard sea-ice model in our work, and although it did cause some problems, we managed to cope ok in the end. It's a potential source of instability due to the way it insulates the ocean (heat transport) from the atmosphere. But of course our method is quite good at picking "balanced" perturbations :-)

5:56 am  
Blogger Belette said...

If "static" sea ice means turning off the ice dynamics (ie movement) then this sounds like a Bad Idea to me. Snow: there is a "white ice" param which should convert xs snow into sea ice if it would depress the snow level below sea level.

Wouter: I am indeed taking the 14:?5 flight via LA. Hope we can meet up...

10:15 am  
Blogger crandles said...

It could easily be a 'terminological inexactitude'. I am sure I read something on a CPDN thread somewhere but I don't really trust my memory to tell you what it said. (I did say I think.) After a bit of seaching I put up a post to see if anyone can help here

2:45 pm  
Blogger crandles said...

Just a quick thought, is it normal for slab models not to have sea ice movement?

3:02 pm  
Blogger Belette said...

Chris - I've never used the slab model (ugh :-) so I'm not sure. But now I know what you look like... I would suspect that there should be some kind of sea ice flux correction is the ice isn't moving, but I'm only guessing.

3:39 pm  

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