Restart file date for a branch run

[pgoddard08]

Hello,

Using E3SMv2.0 NARRM.

I am attempting to start a branch run from restart files from the pre-industrial simulation (year 0101). I'd like to use these restart files as ICs for a WCYCL20TR simulation that begins in the year 1850. Here is my run script:

#!/bin/bash -fe

# this was downloaded from https://raw.githubusercontent.com/E3SM-Project/e3sm_data_docs/refs/heads/main/run_scripts/v2/original/run.v2.NARRM.historical_0101.sh on September 11, 2025 at approximately 12:11 PM Eastern

# E3SM Water Cycle v2 run_e3sm script template.
#
# Inspired by v1 run_e3sm script as well as SCREAM group simplified run script.
#
# Bash coding style inspired by:
# http://kfirlavi.herokuapp.com/blog/2012/11/14/defensive-bash-programming

# TO DO:
# - custom pelayout

main() {

# For debugging, uncomment libe below
#set -x

# --- Configuration flags ----

# Machine and project
readonly MACHINE="BigRed200"
readonly PROJECT="r00025"

# Simulation
readonly COMPSET="WCYCL20TR"
readonly RESOLUTION="northamericax4v1pg2_WC14to60E2r3"
readonly CASE_NAME="v2.NARRM.historical_from_pi0101_20260206"
readonly CASE_GROUP="v2.RRM"

# Code and compilation
readonly CHECKOUT="20211019"
readonly BRANCH="b936852235e3cf8512909d952929e30a1638b5a4" # master as of 20211019
readonly DEBUG_COMPILE=false

# Run options
readonly MODEL_START_TYPE="hybrid"  # 'initial', 'continue', 'branch', 'hybrid'
readonly START_DATE="1850-01-01"

# Additional options for 'branch' and 'hybrid'
readonly GET_REFCASE=TRUE
readonly RUN_REFDIR="/N/project/MSB_Project/E3SMv2.0_NARRM_ICs_and_Restart_Files/from_PI_Control_0101/archive/rest/0101-01-01-00000"
readonly RUN_REFCASE="v2.NARRM.piControl"
readonly RUN_REFDATE="0101-01-01"   # same as MODEL_START_DATE for 'branch', can be different for 'hybrid'

# Set paths
readonly CODE_ROOT="/N/project/MSB_Project/E3SMv2.0_NARRM/E3SM"
readonly CASE_ROOT="/N/project/MSB_Project/E3SMv2.0_NARRM_scripts/${CASE_NAME}"
readonly CASE_RUN_SCRATCH="/N/scratch/pgoddard/cime_scratch/E3SMv2.0_NARRM/${CASE_NAME}"
readonly ARCHIVE_ROOT=${CASE_ROOT}

# Sub-directories
readonly CASE_BUILD_DIR=${CASE_ROOT}/build  # Don't put build in scratch
readonly CASE_ARCHIVE_DIR=${CASE_RUN_SCRATCH}/archive

I am met with an error, e.g. log.ocean.0000.err which contains this text:

----------------------------------------------------------------------
Beginning MPAS-ocean Error Log File for task     787 of    1024
    Opened at 2026/02/09 11:39:00
----------------------------------------------------------------------

ERROR: File /N/scratch/pgoddard/cime_scratch/E3SMv2.0_NARRM/v2.NARRM.historical_from_pi0101_20260206/run/v2.NARRM.piControl.mpaso.rst.0101-01-01_00000.nc does not contain the time 1850-01-01_00:00:00
CRITICAL ERROR: Core init failed for core ocean
Logging complete.  Closing file at 2026/02/09 11:39:00

I thought for branch runs the start date and the run ref date could differ. Can someone help me understand my error?

Many thanks,
Paul

[jonbob]

Hi Paul,

You can only change the start date for startup and hybrid runs. This is the section from env_run.xml:

    <entry id="RUN_STARTDATE" value="0001-01-01">
      <type>char</type>
      <desc>
      Run start date (yyyy-mm-dd). Only used for startup or hybrid runs.
    </desc>

You may want to change to a hybrid run, if that is your intention. If so, please be aware that you will have to remove or rename the xtime setting in the mpas restart files. One way to do that is using ncrename, like this:

ncrename -v xtime,xtime.orig {mpas_restart_file}

[pgoddard08]

Thank you for the quick reply. I just realized I made a mistake in my question, I meant to state "I thought for hybrid runs the start date and the run ref date could differ"

So, I do want to run a hybrid run. And to do so, I'll need to remove or rename the xtime setting in the mpas restart files. Do I need to do the same for eam, elm, and mosart restart files?

[jonbob]

No, just mpas-ocean and mpas-seaice

[pgoddard08]

Great, thanks, Jon