[Liwg-core] relevant co-chairs notes 6-6-17
sacks at ucar.edu
Tue Jun 6 11:09:20 MDT 2017
Here are the most relevant notes from today's co-chairs meeting.
My executive summary:
(1) Based on Jan's analysis of the snow albedo changes, we won't go with that change – instead, the land group will try to get lower albedos by changing the snow cover fraction parameterization, which shouldn't impact the ice sheets much
(2) Run #173 (currently 30 years in) is a possible candidate for a "final, good" configuration. Once that gets a little further along (maybe in the next day or two?) it would be good for someone from the LIWG to look at some diagnostics for Greenland in that run.
Peter Lawrence: before tweaking land albedos, albedos were significantly higher than MODIS both in high latitudes and desert regions
Dave L: However, lowering albedos degrades simulation of ice sheet melt over Antarctica (and maybe Greenland?). So we don't want to do an extreme change to the albedos
Dave L: Expects we can get a similar response by changing snow cover fraction – and that probably wouldn't have negative impacts on the ice sheets.
Dave L: Also note that land albedos are actually a bit lower than CCSM4. It may still be that CLM's albedos are too high, but he doesn't have a lot of faith in the MODIS albedos.
Plan for runs
• Keep #173 going – this includes atmosphere changes without land snow changes
Look at this – particularly over Greenland and throughout the Arctic, because that's where a lot of the changes are.
If this looks good, then do a 20th century with this
• Start another run with land snow changes – probably get decreased albedos by changing snow cover fraction parameterization, rather than changing snow albedos more directly, because this will be better for the ice sheets. (#174)
• Start another run with new land snow changes plus the atmosphere changes (#174 changes on top of #173)
Tentative meeting Friday at 10 am
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