[Cesm2control] Follow up from yesterday's co-chair meeting

Gokhan Danabasoglu gokhan at ucar.edu
Wed Feb 21 07:43:45 MST 2018


Dear All,



I just want to follow up with yesterday’s co-chairs meeting to clarify
where we are with respect to a frozen CESM2 configuration. ….



Towards the end of our meeting, the land model folks indicated that there
is likely a heat budget problem in the land model that shows up as a
positive heat flux of about 0.08 W/m2 into the land model. Given that this
amount is of the same order of magnitude that we strive to achieve for our
TOA, we need to figure out how this heat flux issue originates. It is my
understanding that the LMWG folks are working on this, and they hope to
have an answer / solution this week.



With this background, the final configuration of the CESM2 will then have:

- correction for the land model heat flux

- new WACCM forcing (from #265)

- new H2O external forcing

- nitrogen deposition for the CLM

- corrected solar forcing

- increased local vertical mixing in overflow regions to reduce tracer
extrema



I believe we should start a new control simulation with this configuration
as in #266. I note that #266 includes snow / sea-ice albedo changes, but
not any adjustments in the atmospheric model to retune the TOA. With the
corrected heat fluxes in the land model, perhaps we will not need any of
these additional retunings.



Our backup configuration is #269.



Best,
Gokhan
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