[Liwg-core] Good news: realistic GrIS ablation!; and next telecom

Miren Vizcaino M.Vizcaino at tudelft.nl
Fri Mar 10 12:31:18 MST 2017

Hi Jer

Downscaled SMB is included in the figure I sent.

Maximum snow depth is 10 m w.e. for GrIS. This means that we the snow/firn pack needs many years for equilibrium, so we need a spin-up strategy that can be acceptable for the CLM folks as well. We have run only 7 years so far. We need to run further to get an idea of the equilibrium snow/firn thickness distribution per elevation class per grid cell. If this becomes clear early in the simulation, we could implement something in the line proposed by Bill Sacks during the Winter Meeting. But first we need to run more years to understand the dynamics towards equilibrium.

Thanks, Miren

On Mar 10, 2017, at 5:10 PM, Jeremy Fyke wrote:

Hey all,

Thanks for update, Miren!  A few follow-up questions:
-what maximum snow depth are you using here?
-what does downscaled SMB look like (which is ultimately what the ice sheet will see)?


On Fri, Mar 10, 2017 at 8:59 AM, Lenaerts, J.T.M. (Jan) <j.lenaerts at uu.nl<mailto:j.lenaerts at uu.nl>> wrote:
Hi Miren (and Raymond),

Thanks for the message and all the work. This looks great and is consistent with what we saw earlier, with the additional improvement of the Northern Greenland bias with your suggested initialisation. I am really curious how this will look in the 20th century!

I cannot make it next Wednesday but I am happy to discuss with Leo and/or you beforehand.

All the best,


On 10 Mar 2017, at 14:29, Miren Vizcaino <M.Vizcaino at tudelft.nl<mailto:M.Vizcaino at tudelft.nl>> wrote:

Dear All,

This email contains two messages

1 - Good news. We have tried the new SCF with #134 and snow thickness reset to 1 m w.e. over the GrIS, and now CESM is able to realistically simulate the ablation areas at ALL ice sheet margins, including N and NE (see attached figure)!
The reason for the differences with the “control” #134 presented by Leo at the meeting is that 1 m w.e. is below Wmax = 2 m w.e. The span-up #134 snow/firn cover prevented thick snow/firn columns from ablating.

Congratulations and many thanks to everybody, very specially to Leo the implementation of the SCF and to Raymond for his work on the impact of snow/firn initialization.

2 - I propose to have a telecom next Wednesday, e.g., to discuss how to spin-up the snow/firn pack in time for the official CESM2.0 pre-industrial BG control.

Regards, Miren

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Jan Lenaerts
IMAU, Utrecht University || University of Colorado
@lenaertsjan<https://twitter.com/lenaertsjan> || website<http://www.colorado.edu/lab/icesheetclimate/>

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