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2e5e87c
For ctsm5.4 replace WhatsNewInCTSM5.3.md with WhatsNewInCTSM5.4.md
slevis-lmwg Jul 25, 2025
eadb1f7
Draft WhatNewinCTSM54_release_notes (mostly deletes, some additions)
slevis-lmwg Jul 29, 2025
50c7143
Draft WhatsNewInCTSM5.4.md with ChangeLog info from ctsm5.3.022 to .065
slevis-lmwg Jul 29, 2025
5510a7e
Bring back WhatsNewInCTSM5.3.md but in the /doc directory
slevis-lmwg Aug 27, 2025
224cf73
An update to WhatsNewInCTSM5.4.md about changes in ctsm5.3.040
slevis-lmwg Aug 27, 2025
9f1fb9f
Merge tag 'alpha-ctsm5.4.CMIP7.18.ctsm5.3.082' into WhatsNewinCTSM54_…
slevis-lmwg Nov 18, 2025
560ad74
User's Guide updates about splitting hX to hXa and hXi files
slevis-lmwg Nov 24, 2025
93b0dd4
Additional User's Guide updates about splitting hX to hXa and hXi files
slevis-lmwg Nov 24, 2025
b883127
Updated WhatsNewInCTSM54
slevis-lmwg Nov 24, 2025
a8b1afe
Minor improvements to documentation
slevis-lmwg Nov 25, 2025
060bd7c
Update README and default_data*.cfg files to refer to 5.4, not 5.3
slevis-lmwg Nov 25, 2025
addc86e
Corrections to the WhatsNew markdown file
slevis-lmwg Nov 25, 2025
cd3558f
More corrections to the WhatsNew file
slevis-lmwg Nov 25, 2025
b5fa1cf
More corrections to the WhatsNew file
slevis-lmwg Nov 25, 2025
7d56d4b
Small corrections to README and CONTRIBUTING.md
slevis-lmwg Nov 26, 2025
90a165f
Revert updates to two default_data*cfg files to avoid testing in this PR
slevis-lmwg Nov 26, 2025
74ed7a5
Update tools in /contrib to make h0a the default option (instead of h0)
slevis-lmwg Nov 26, 2025
c24c69b
Merge branch 'alpha-ctsm5.4.CMIP7' into WhatsNewinCTSM54_release_notes
slevis-lmwg Nov 27, 2025
f84ee6d
Merge tag 'alpha-ctsm5.4.CMIP7.19.ctsm5.3.085' into WhatsNewinCTSM54_…
slevis-lmwg Nov 27, 2025
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2 changes: 1 addition & 1 deletion CONTRIBUTING.md
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Expand Up @@ -45,4 +45,4 @@ Code conventions: https://github.com/ESCOMP/ctsm/wiki/CTSM-coding-guidelines

#### Code of Conduct:

See the `CODE_OF_CONDUCT.md` file for expectations of how to work in the community.
See https://github.com/ESCOMP/CTSM?tab=coc-ov-file for expectations of how to work in the community.
13 changes: 8 additions & 5 deletions README
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@@ -1,6 +1,6 @@
$CTSMROOT/README 09/05/2024
$CTSMROOT/README 11/24/2025

Community Terrestrial Systems Model (CTSM) science version 5.3 series -- source code, tools,
Community Terrestrial Systems Model (CTSM) science version 5.4 series -- source code, tools,
offline-build and test scripts. This gives you everything you need
to run CTSM with CESM with the CMEPS driver and CDEPS data models to provide CRUJRA or GSWP3 forcing data (some older options also available) in
place of a modeled atmosphere.
Expand All @@ -15,6 +15,10 @@ For lists of current bugs (issues) and current development see the CTSM GitHub p

https://github.com/ESCOMP/CTSM

For Code of Conduct (how to work with each other on the CTSM project):

https://github.com/ESCOMP/CTSM?tab=coc-ov-file

INFORMATION ON THE CMEPS DRIVER:

https://escomp.github.io/CMEPS
Expand Down Expand Up @@ -76,8 +80,7 @@ README ------------------- This file
README.md ---------------- File that displays on github under https::/github.com/ESCOMP/CTSM.git
README.rst --------------- File that displays under the project in github
README_GITFLEXIMOD.rst --- Information on how to work with git-fleximod for CTSM
WhatsNewInCTSM5.3.md ----- Overview document of the changes between ctsm5.2.0 and ctsm5.3.0
CODE_OF_CONDUCT.md ------- Code of Conduct for how to work with each other on the CTSM project
WhatsNewInCTSM5.4.md ----- Overview document of the changes between ctsm5.3 and ctsm5.4
Copyright ---------------- CESM Copyright file
doc/UpdateChangeLog.pl --- Script to add documentation on a tag to the
ChangeLog/ChangeSum files
Expand Down Expand Up @@ -168,7 +171,7 @@ src/unit_test_stubs Unit test stubs that replicate CTSM code simpler

cd $CIMEROOT/scripts
./create_newcase # get help on how to run create_newcase
./create_newcase --case testI --res f19_g17_gl4 --compset I2000Clm60BgcCrop
./create_newcase --case testI --res f09_t232 --compset I2000Clm60BgcCrop
# create new "I" case for default machine at 1.9x2.5_gx1v7
# "I2000Clm60BgcCrop" case is clm6_0 physics, CDEPS, and inactive ice/ocn/glc
# and MOSART for river-routing
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150 changes: 150 additions & 0 deletions WhatsNewInCTSM5.4.md
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# What's new in CTSM 5.4 (tag `ctsm5.4.0xx`)

# Purpose and description of changes since CTSM 5.3 (tag `ctsm5.3.021`)

## New features

* New surface datasets from CMIP7 data including PFT and urban distributions, land use transitions, population density, and atmospheric C isotopes. These data are only available through the historical record (1850-2023), and
* are not available for future periods (presently known as SSP),
* for future periods and N deposition we continue to use CMIP6 data from CESM2.
* Option to use CRUJRA2024 atmospheric driver data with clm6 and clm5 physics options ([PR #2956](https://github.com/ESCOMP/ctsm/pull/2956)), this is the default data-atmosphere (DATM) for clm6. This CRUJRA dataset covers 1901-2023, whereas previous GSWP3 only covers 1901-2014.
* Capability to run single-point PLUMBER tower sites, similar to the NEON tower capability ([issue #1487](https://github.com/ESCOMP/CTSM/issues/1487)). Initial conditions are not provided for PLUMBER sites.
* New CLM\_CMIP\_ERA flag in env\_run.xml. Valid options are cmip7 and cmip6. Defaults to cmip7 except in compsets containing SSP for which it defaults to cmip6 because there are no future-period datasets yet available for CMIP7.
* Automatic, more flexible use of anomaly forcings for CMIP6 ISSP cases, which also use the cmip6 CLM\_CMIP\_ERA flag: [Documentation](https://escomp.github.io/CTSM/users_guide/running-special-cases/Running-with-anomaly-forcing.html)

* Unsupported script that checks for spinup equilibrium in `tools/contrib/` for spectral element grids ([PR #2991](https://github.com/ESCOMP/ctsm/pull/2991)).
* New paramfile tools that allow users to query and modify CLM parameter files ([documentation](https://escomp.github.io/CTSM/users_guide/using-clm-tools/paramfile-tools.html))
* Optional time-evolving \`leafcn\_target\`. More under “Additional detail” below.
* New vertical movement scheme for soil nitrate, which is off by default (PR [#2992](https://github.com/ESCOMP/CTSM/pull/2992)).
* Documentation improvements and new URL: https://escomp.github.io/CTSM/index.html.
* FATES:
* Grazing ([sci.1.81.0\_api.37.1.0](https://github.com/NGEET/fates/releases/tag/sci.1.81.0_api.37.1.0)).
* Johnson and Berry 2021 electron transport model ([sci.1.85.0\_api.40.0.0](https://github.com/NGEET/fates/releases/tag/sci.1.85.0_api.40.0.0)).
* Managed Fire ([sci.1.87.0\_api.41.0.0](https://github.com/NGEET/fates/releases/tag/sci.1.87.0_api.41.0.0)).

## Answer changes

Changes to defaults for \`clm6\` physics:

* New CMIP7 surface and landuse timeseries datasets (see in Additional Details below).
* New namelist variables \`snow\_thermal\_cond\_glc\_method\` and \`snow\_thermal\_cond\_lake\_method\` ([PR #3072](https://github.com/ESCOMP/CTSM/pull/3072)). Snow thermal conductivity uses Jordan1991 over glaciers to reduce Greenland melt rates by default and Sturm over land and lake land units.
* Bytnerowicz is now the default nfix\_method for clm6 (https://github.com/ESCOMP/ctsm/pull/2972) which revises the temperature function for nitrogen fixation, replacing the Houlton *et al.* function.
* Updates to MEGAN for BVOCs (https://github.com/ESCOMP/CTSM/pull/3065 https://github.com/ESCOMP/CTSM/pull/3309). Removes dependence on soil moisture from clm6 physics.
* New model parameter values that were calibrated to improve carbon cycle representation with CRUJRA.
* New model parameter values that were calibrated to improve the fire model. Now using li2024 fire code.
* New initial conditions files for f09 ("1-degree" 1850, 2000), f19 (“2-degree” 1850), and ne30 (1850, 1979, 2000\) resolutions.
* Change default for glcmec\_downscale\_longwave to FALSE for clm6 physics as turning off the LW downscaling improves the melt and runoff biases.
* See “Changes to FATES and the FATES parameter file” below.
* Namelist defaults change so that
* use\_c13/use\_c14 are on only for HistClm60Bgc compsets with CRUJRA2024 or CAM7 forcing; examples of when use\_c13/use\_c14 are now off include SSP and single-point compsets, as well as cases using older forcings, such as CAM6, GSWP3v1, Qian, and CRUv7
* when use\_c13 or use\_c14 is on, turn on the corresponding time series file
* irrigation is on for transient cases (1850-2000, 1850-2100, but not for clm4\_5).

Changes for all physics versions:

* Parameters updated: Added MIMICS parameter \`mimics\_fi\` (fraction of litter inputs that bypass litter pools, directly contributing to SOM) and updated other MIMICS parameters (https://github.com/ESCOMP/CTSM/pull/2365) to remove NPP control on turnover, fix density dependent control on turnover, add litterfall fluxes that bypass litter pools and contribute directly to soil organic matter.
* FATES parameter file updated: ([PR \#2965](https://github.com/ESCOMP/CTSM/pull/2965), [PR \#2904](https://github.com/ESCOMP/CTSM/pull/2904), [PR \#1344](https://github.com/NGEET/fates/pull/1344), [PR \#3087](https://github.com/ESCOMP/CTSM/pull/3087)). See “FATES parameter file” section below for details.
* New surface datasets and landuse timeseries files (see “surface datasets” section below).

## Heads up

* History tapes now split into two files from hX to hXi and hXa, where X is the tape number (e.g. h0i/h0a) and where "i" stands for history file containing instantaneous fields, while "a" stands for history file containing non-instantaneous fields. Details in the “history files” section below and in the PRs https://github.com/ESCOMP/ctsm/pull/2445 https://github.com/ESCOMP/MOSART/pull/117 https://github.com/ESCOMP/RTM/pull/61 and the corresponding issues.
* Adding time to 1d weighting fields in transient simulations PR https://github.com/ESCOMP/CTSM/pull/3328
* Regarding CMIP7 vs. CMIP6 inputs:
* We supply only CMIP7 C13/C14 isotope datasets, so these get used regardless of CLM\_CMIP\_ERA setting.
* We supply only CMIP7 population density with clm6 physics in non-SSP cases, because the fire model is calibrated to that; conversely, we supply only CMIP6 population density for pre-clm6 physics and for SSP cases.
* We supply only CESM2 nitrogen deposition (ndep), so this gets used regardless of CLM\_CMIP\_ERA setting.
* For DATM we supply only CMIP6 aerosols.
* For DATM we supply only CMIP6 CO2.
* Issue with DOUT\_S\_SAVE\_INTERIM\_REST [https://github.com/ESCOMP/CTSM/issues/3351](https://github.com/ESCOMP/CTSM/issues/3351) was fixed.
* As of ctsm5.3.040, the new ctsm\_pylib conda environment is incompatible with our tools from before ctsm5.3.040 and vice versa. More under “Additional detail” below.

# Additional detail

## Changes related to history files

(Note 1: The same information in this section applies to MOSART and RTM.
Note 2: The gist of the information in this section also appears in the [CTSM User’s Guide](https://escomp.github.io/CTSM/users_guide/setting-up-and-running-a-case/customizing-the-clm-namelist.html#various-ways-to-change-history-output-averaging-flags)).

Following ctsm5.3.018 "Change history time to be the middle of the time bounds" and keeping CLM history consistent with CAM history, the CTSM5.4 change intends to prevent confusion associated with the time corresponding to instantaneous history fields by putting them on separate files than non-instantaneous fields.

The now separate instantaneous history files represent the exact time step when they were written and do not include a time\_bounds variable. Conversely, non-instantaneous history files represent the period of their time\_bounds variable. As a result, time data on non-instantaneous history files are now read correctly during post processing (e.g. by xarray). Special handling may still be needed for instantaneous history files, whose timestamps represent the date and time at the END of the history timestep. So, e.g., an instantaneous variable saved at the end of year 2023 will get the timestamp 2024-01-01 00:00:00.

Users will now see:

1\) Two history files per clm, mosart, and rtm history tape:
tape h0 becomes h0a and h0i
tape h1 becomes h1a and h1i
...
tape hX becomes hXa and hXi

2\) Two history-restart files per history restart tape:
rh0 becomes rh0a and rh0i
rh1 becomes rh1a and rh1i
...
rhX becomes rhXa and rhXi

The CLM handles empty history (and corresponding history-restart) files by not generating them, while rtm and mosart give an error. Instead of refactoring rtm and mosart to behave like the clm (considered out of scope), we have introduced one active instantaneous field in mosart and one in rtm to bypass the "empty file" error.

## New surface datasets and landuse timeseries files (https://github.com/ESCOMP/CTSM/pull/3482)

* Transient landuse timeseries files going back to 1700 made for f09 and 360x720 grids.
* New resolutions now supported: ne3np4.pg3, mpasa30, ne0np4.NATL.ne30x8 (https://github.com/ESCOMP/CTSM/pull/3482)
* Updates to input datasets (also referred to as raw datasets):
* PFT/LAI/soil-color raw datasets; now from the CMIP7 timeseries that ends in 2023 (Issue [\#2851](https://github.com/ESCOMP/CTSM/issues/2851)).
* Two fire datasets: crop fire peak month and population density (https://github.com/ESCOMP/CTSM/issues/2701 https://github.com/ESCOMP/CTSM/issues/3302).
* Transient (historical) urban datasets are now based on CMIP7 urban data, partitioned into TBD, HD, and MD classes in proportion to GaoOneill present day classification.

## Changes to FATES and the FATES parameter file

* See [HLM-FATES compatibility table](https://fates-users-guide.readthedocs.io/en/latest/user/release-tags-compat-table.html) in the FATES user’s guide for all FATES tags associated with CTSM tag updates
* FATES answer changing updates
* The default hydro solver is updated to 2D Picard from 1D Taylor ([ctsm5.3.027](https://github.com/ESCOMP/CTSM/releases/tag/ctsm5.3.027))
* Simplified leaf sun-shade fraction for two-stream radiation ([sci.1.83.0\_api.39.0.0](https://github.com/NGEET/fates/releases/tag/sci.1.83.0_api.39.0.0))
* Default maximum canopy layer updated from 2 to 3 ([sci.1.87.1\_api.41.0.0](https://github.com/NGEET/fates/releases/tag/sci.1.87.1_api.41.0.0))
* Various bug fixes (see compatibility table)
* FATES Parameter File Updates
* ctsm5.3.025 (API 37\)
* Adds pft-dependent btran model switches
* Adds parameters for land use grazing
* Updates the FATES z0mr turbulence parameters for consistency with CLM
* ctsm5.3.027 (API 38\)
* Migrates a number of global parameter file variables to the namelist
* Adds \`fates\_leaf\_fnps\` parameter for the electron transport model
* \`fates\_leaf\_theta\_cj\_c3\` and \`fates\_leaf\_theta\_cj\_c4\` depricated
* ctsm5.3.045 (API 40\)
* Changes to the default competitive exclusion parameter from probabilistic to rank-ordered sorting of cohorts by default
* Sets the logging default to clear cut
* Refactors the pft-specific phenology habit selection into a single parameter
* ctsm5.3.070 (API 41\)
* Add parameters for the managed fire feature addition
* Corrects the fates landuse crop pft to c3 cool grass

## New ctsm\_pylib conda environment

If you have a ctsm\_pylib conda environment installed from before ctsm5.3.040, you may want to keep that under a different name. We suggest the following command for doing this in a local copy of ctsm5.3.040 or later:

```shell
./py_env_create -r ctsm_pylib_old
```

This first renames your existing ctsm\_pylib to ctsm\_pylib\_old and then installs the Python 3.13.2 version as ctsm\_pylib. If you are unsure whether you already have ctsm\_pylib installed, use the same command regardless, as it will skip the renaming step if necessary.

Information about additional py\_env\_create options — including how to install a fresh copy of the old conda environment — is available as follows:

```shell
./py_env_create --help
```

## Potentially time-evolving \`leafcn\_target\` replaces time-constant \`leafcn\`

The former is calculated as a function of the latter and can be time-evolving depending on new paramfile parameter \`leafcn\_co2\_slope\` https://github.com/ESCOMP/ctsm/pull/1654. The time-evolving effect defaults to off with \`leafcn\_co2\_slope\` \= 0 on the parameter file.

# Simulations supporting this release by providing initial conditions

* f19 \`Clm60BgcCruJra\` 16pft: https://github.com/NCAR/LMWG_dev/issues/125
* f09 with \`Clm60BgcCropCruJra\`: https://github.com/NCAR/LMWG_dev/issues/124
* ne30 with \`Clm60BgcCropCruJra\`: https://github.com/NCAR/LMWG_dev/issues/123 (123\_HIST\_popDens)
* ne30 SP https://github.com/NCAR/LMWG_dev/issues/126
* f09 SP https://github.com/NCAR/LMWG_dev/issues/127

File renamed without changes.
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Expand Up @@ -60,9 +60,9 @@ To run CTSM at a NEON site, change directories to where the run_tower tool is lo
When a simulation completes, the data are stored in the archive directory under ``CTSM/tools/site_and_regional/archive``. In this directory you will find files that include data for every day of the simulation, as well as files that average model variables monthly. The output file names are automatically generated and are composed of the simulation name, which includes the site name, type of simulation (eg, ``transient``), and the date of simulated data.
The tower simulations generate two types of files:

1) ``h0`` Variables that are averaged monthly. One file is available for every month of the simulation. These files include hundreds of variables.
1) ``h0a`` Variables that are averaged monthly. One file is available for every month of the simulation. These files include hundreds of variables.

2) ``h1`` Variables that are recorded every 30 minutes. Values are aggregated into one file for each day of the simulation. Each file includes 48 data points for selected variables.
2) ``h1a`` Variables that are recorded every 30 minutes. Values are aggregated into one file for each day of the simulation. Each file includes 48 data points for selected variables.

=========================================
PLUMBER Tower Single Point Simulations
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Expand Up @@ -59,18 +59,18 @@ In a GDD-generating run, crops are planted on the specified sowing dates and are
generate_crop_gdds = .true.
use_mxmat = .false.

! (h0) Save default variables monthly instead of daily to save space
! (h0a) Save default variables monthly instead of daily to save space
hist_nhtfrq = 0
hist_mfilt = 12

! (h1) Annual outputs for GDD generation
! (h1i) Annual outputs for GDD generation
hist_fincl2 = 'GRAINC_TO_FOOD_PERHARV', 'GRAINC_TO_FOOD_ANN', 'SDATES', 'SDATES_PERHARV', 'SYEARS_PERHARV', 'HDATES', 'GDDHARV_PERHARV', 'GDDACCUM_PERHARV', 'HUI_PERHARV', 'SOWING_REASON_PERHARV', 'HARVEST_REASON_PERHARV'
hist_nhtfrq(2) = 17520
hist_mfilt(2) = 999
hist_type1d_pertape(2) = 'PFTS'
hist_dov2xy(2) = .false.

! (h2) Daily outputs for GDD generation
! (h2a) Daily outputs for GDD generation
hist_fincl3 = 'GDDACCUM', 'GDDHARV'
hist_nhtfrq(3) = -24
hist_mfilt(3) = 365
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