[Liwg-core] Timeline and details for tweaking rain-snow repartitioning ramp

Miren Vizcaino M.Vizcaino at tudelft.nl
Wed Mar 8 06:05:28 MST 2017

Hi again,

in looking at your plots again I cannot quantify the reduction from turning off repartition in northern Greenland or separate it from the noise of the precipitation variability in 3 years,

so please let me dig into the results before getting to any conclusion. Sorry for the previous email. Thanks, Miren

On Mar 7, 2017, at 12:37 PM, Miren Vizcaino <M.Vizcaino at tudelft.nl<mailto:M.Vizcaino at tudelft.nl>> wrote:

Hi Leo

Thanks a lot. We see turning off repartition reduces growth rates - except in southern Baffin Island (?)-  but not sufficiently.

Laura and me are currently analysing your runs with detail. Raymond is going to set a couple of very extreme idealized runs with your set-up to see if he can trigger high ablation both over the ice sheet and tundra

We’ll keep you posted

Thanks, Miren

On Mar 7, 2017, at 10:10 AM, Kampenhout, L. van (Leo) <L.vanKampenhout at uu.nl<mailto:L.vanKampenhout at uu.nl>> wrote:

new plot with snow height growth in the period 0001-01 to 0003-08 :


On 07 Mar 2017, at 09:37, Miren Vizcaino <M.Vizcaino at tudelft.nl<mailto:M.Vizcaino at tudelft.nl>> wrote:

Hi, Bill
We are doing analysis at Delft and will show results today. Leo set some  BG 3-yr runs branching from #134. However, it is likely that we will see little effect if any in 3 years runs since we start from 10 m w.e. And all rain will likely refreeze. Raymond is setting a reset simulation to start from thin snow layer. We want to use the same simulation to test if the new SCF works in preventing bare ice burial in the N ablation zone. He'll run first 5 years and check trends. Laura will additionally set another run with 100% vegetated N Greenland tundra areas. Bill, is it straightforward to set elevation classes for tundra areas?

Sent from my iPhone

On 7 Mar 2017, at 03:55, Bill Sacks <sacks at ucar.edu<mailto:sacks at ucar.edu>> wrote:

Hi Leo, Jan & Miren,

Dave Lawrence pointed out to me that, if we want any changes to the rain-snow repartitioning ramp for CESM2, these really need to get in very, very soon. The end of this week would be safest, but middle of next week may be okay, too. So I wanted to make sure you're aware of this tight timeline.

Dave also expressed a preference for keeping 0 as the lower bound of the ramp for non-glacier landunits, so that any tweaks would involve shifting the 2° upper bound – so we could end up with, say, a ramp from 0 - 1 C, rather than, say, -1 to 1 C. It doesn't sound like he's totally set on that, though – I think it was mostly based on personal / anecdotal experience.

Leo, or whoever is doing these runs: Can you let us know what you were planning to test so we can all be on the same page about this?

Bill S

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