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With these options, we can submit once for each 10 year chunk, and then go back and check our spin-up state. Looking a few select fields, after 50 90 years we have the following (these are all land-only area-weighted global means):
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The comparison is between a spin-up with a coldstart initial condition (described here) and an initial condition remapped from a lower resolution (described in the following section). While total water storage (TWS) appears to be at least approaching an equilibrium value, it is still increasing over the last decade of the simulation. This appears to be typical for column integrated quantities. The heat content (HCSOI) shows a similar story:
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However, a more alarming example is the surface water depth (H2OSFC):
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After 50 90 years, this quantity is still increasing at a linear rate. I suspect this is due to the configuration of the I-case, but it’s a little odd. This does not seem to happen in the coupled cases (i.e., the piControl simulation referenced in the following section).
Digging a little further, while the global means appear to be coming to equilibrium, regional means are not. For this arctic RRM example, we are interested in the arctic region. Looking instead at averages north of 60 N, we see that quantities are still changing fairly rapidly:
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Even after 90 years, and even after 40 years in the remapped case, the arctic appears to still be spinning up.
Remapping an existing initial condition

Add a captionWith the apparent slow spin-up of the land model from a cold-start, even for an I-case, it makes sense to try to get a jump-start on spin-up by starting with an existing spun-up initial condition, and remapping to our target grid, and then performing a (hopefully shorter) additional adjustment/spin-up period on the new grid. ELM provides a tool for remapping initial conditions, as it is apparently not as straightforward a process as remapping data for the other components, I think because the land model restart files describe only a subset of the grid and in some specialized format (someone who knows more about this should comment here, I’m still surprised we need a special tool to do this). That remap tool is in:
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components/elm/tools/clm4_5/interpinic |
Other than some simple Makefile and source code fixes to build on cori (upcoming in a PR), the tool is easy to build and run. The following was sufficient to create a remapped initial condition from a 1000 year pre-industrial control simulation at ne30:
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#!/bin/bash
# Source our configuration file to set paths/variables
source config.sh
# First, build initial condition interpolator
rm env_mach_specific.xml
${e3sm_root}/cime/tools/configure --machine ${machine} || exit 1
source .env_mach_specific.sh || exit 1
cd ${e3sm_root}/components/elm/tools/clm4_5/interpinic/src
USER_FC=${fortran_compiler} LIB_NETCDF="`nc-config --libdir`" INC_NETCDF="`nf-config --includedir`" make VERBOSE=2
# Next, run using a well-spun-up initial condition
source_inic_file=/global/cscratch1/sd/bhillma/e3sm/cases/v2rc3.piControl.ne30pg2_EC30to60E2r2/archive/rest/1001-01-01-00000/20210528.v2rc3c.piControl.ne30pg2_EC30to60E2r2.chrysalis.elm.r.1001-01-01-00000.nc
target_inic_file=~/codes/e3sm/cases/add-arcticx4v1-rrm.arcticx4v1pg2_oARRM60to10.ICRUELM.spinup1/run/add-arcticx4v1-rrm.arcticx4v1pg2_oARRM60to10.ICRUELM.spinup1.elm.r.0091-01-01-00000.nc
output_inic_file=${output_root}/${lnd_grid_name}.elm.r.1001-01-01-00000.nc
cp ${target_inic_file} ${output_inic_file}
cd ${e3sm_root}/components/elm/tools/clm4_5/interpinic
./interpinic -i ${source_inic_file} -o ${output_inic_file} |
Using the resulting remapped initial condition, I wanted to see how much this would accelerate the adjustment to a different forcing, so ran another I-case (using the above setup for running cold start but instead from this remapped initial condition). The global means actually look quite good, even at the start of this simulation:
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However, looking at just the arctic (60N to 90N), it definitely looks like things are still spinning up after 50 years:
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