Which compset to use for interactive land, data ocean and SSP585 CO2 forcing?

[UllaH]

I'm interested in setting up a case where the SST and CO2 are prescribed, based on the SSP585 scenario as a baseline, but where the land component is otherwise responding to the forcing (I'm interested in the response of things like snow cover, river flow, soil moisture) to a change in CO2 and SST.

I know that the F-compsets uses a docn, which I'm interested in. But there are so many options, and it's not clear to me which to pick.

For example, these experiments: HIST_CAM60_CLM50%BGC-CROP_CICE%PRES_DOCN%DOM_MOSART_CISM2%NOEVOLVE_SWAV from the list of scientifically validated experiments are described as having
"a selection of land surface characteristics is prescribed rather than interactively calculated" - but how do I find out which are prescribed? And what setting do I change to have the land respond interactively to the atmospheric forcing?

Thank you for any insights,
Ulla

 

[nusbaume]

Hi Ulla,

Do you want just prognostic land, or do you want a prognostic atmosphere as well? If you want both a prognostic land and atmosphere then you are correct that you'll want an F-compset. However, if you want only the land component to be prognostic (with all of the atmospheric forcing being prescribed) then you'll want to do an I-compset.

In general any compset that has CLM50 in it will have a prognostic land surface that responds interactively. However, in some compsets the vegetation coverage, plant phenology, etc. will be prescribed. The various component options for CLM5 can be found in the following file:

<CESM>/components/clm/cime_config/config_component.xml

Where <CESM> is wherever you cloned or downloaded your copy of the CESM2 model.

Finally, I am moving this thread to the land model forum, as they will be more likely to answer any specific questions you might have about the various CLM options.

Hope that helps, and have a great day!

Jesse

 

[UllaH]

Hi Jesse,

Thank you so much. This makes sense - I have a follow up questions for the land model community -

What is the difference between
f.e21.FHIST_SSP585.f09_f09_mg17.CMIP6-lfmip-pdLC.001

and

f.e21.FHIST_SSP585.f09_f09_mg17.CMIP6-lfmip-rmLC.001

in other words, what is rmLC and pdLC ?

 

[strandwg]

Hi Jesse,

Thank you so much. This makes sense - I have a follow up questions for the land model community -

What is the difference between
f.e21.FHIST_SSP585.f09_f09_mg17.CMIP6-lfmip-pdLC.001

and

f.e21.FHIST_SSP585.f09_f09_mg17.CMIP6-lfmip-rmLC.001

in other words, what is rmLC and pdLC ?

Those experiments are described in

https://gmd.copernicus.org/preprints/gmd-2016-72/gmd-2016-72-manuscript-version6.pdf

Tier 1 experiments in LFMIP
Similar to the setup of GLACE-CMIP5 (Seneviratne et al., 2013), the core experiments of LFMIP (tier 1) evaluate two different sets of prescribed land surface conditions (snow and soil moisture):

LFMIP-pdLC: the experiments comprise transient coupled atmosphere–ocean simulations in which a selection of land surface characteristics is prescribed rather than interactively calculated in the model. This “climatological” land surface forcing is calculated as the mean annual cycle in the period 1980–2014 from the historical GCM simulations. The experiment aims at diagnosing the role of land–atmosphere feedback at the climate timescale. Seneviratne et al. (2013) found a substantial effect of changes in climatological soil moisture on projected temperature change in a future climate, both for seasonal mean and daytime extreme temperature in summer. Effects on precipitation are less clear, and the multi-model nature of LS3MIP is designed to sharpen these quantitative effects. Also, LS3MIP will take a potential damping (or amplifying) effect of oceanic responses on altered land surface conditions into account, 10http://www.climate-cryosphere.org/activities/targeted/ esm-snowmip Geosci. Model Dev., 9, 2809–2832, 2016 www.geosci-model-dev.net/9/2809/2016/ B. van den Hurk et al.: LS3MIP (v1.0) contribution to CMIP6 2819 in contrast to GLACE-CMIP5. Experiments using this setup (i.e., coupled ocean) in a single-model study have shown that the results could be slightly affected by the inclusion of an interactive ocean, although the effects were not found to be large overall (Orth and Seneviratne, 2016).

LFMIP-rmLC: a prescribed climatology using a transient 30-yr running mean, where a comparison to the standard CMIP6 runs allows diagnosis of shifts in the regions of strong land–atmosphere coupling as recorded by e.g., Seneviratne et al. (2006), and shifts in potential predictability related to land surface states (Dirmeyer et al., 2013).

 

[oleson]

Those are both CMIP6 experiments. You can find more information about them here:

CESM2 Experiments, Data & Diagnostic Output

Multi-decadal model runs of given component sets at the target resolution, followed by scientific review of the model output diagnostics

csegweb.cgd.ucar.edu

The "pd" uses prescribed land surface climatology (soil moisture) derived from "present climate" conditions (1980-2014).
The "rm" uses land surface climatology (soil moisture) prescribed as 30-year monthly running means.

 

[UllaH]

Thank you so much!

 

[UllaH]

I have a follow up question here -
which settings do I need to change in order to get the 'pd' or 'rm' version of the land model respectively? They appear to have identical compsets as far as I can tell.

 

[oleson]

Those are specialized simulations and aren't available out of the box. The "pd" and "rm" configurations are specified by settings in the lnd_in namelist.
Are you trying to repeat these specific simulations or are you just intending to run with prescribed soil moisture in general?

 

[UllaH]

I'm trying to run a simulation with prescribed, time dependent SST where the soil moisture evolves as a function of changes in precip patterns

 

[oleson]

You wouldn't want to use the pd or rm configurations then since they prescribe soil moisture. A compset with CLM5%BGC-CROP included would give you a fully interactive land including where soil moisture evolves as a function of changes in precip patterns.

 

[UllaH]

Aha. That makes sense! Thank you