diff --git a/modulefiles/gsi_acorn.intel.lua b/modulefiles/gsi_acorn.intel.lua
new file mode 100644
index 000000000..401a2a98e
--- /dev/null
+++ b/modulefiles/gsi_acorn.intel.lua
@@ -0,0 +1,50 @@
+help([[
+]])
+
+
+local PrgEnv_intel_ver=os.getenv("PrgEnv_intel_ver") or "8.1.0"
+local intel_ver=os.getenv("intel_ver") or "19.1.3.304"
+local craype_ver=os.getenv("craype_ver") or "2.7.8"
+local cray_mpich_ver=os.getenv("cray_mpich_ver") or "8.1.7"
+local cmake_ver= os.getenv("cmake_ver") or "3.20.2"
+local python_ver=os.getenv("python_ver") or "3.8.6"
+local prod_util_ver=os.getenv("prod_util_ver") or "2.0.10"
+
+local netcdf_ver=os.getenv("netcdf_ver") or "4.7.4"
+local bufr_ver=os.getenv("bufr_ver") or "11.7.0"
+local bacio_ver=os.getenv("bacio_ver") or "2.4.1"
+local w3emc_ver=os.getenv("w3emc_ver") or "2.9.2"
+local sp_ver=os.getenv("sp_ver") or "2.3.3"
+local ip_ver=os.getenv("ip_ver") or "3.3.3"
+local sigio_ver=os.getenv("sigio_ver") or "2.3.2"
+local sfcio_ver=os.getenv("sfcio_ver") or "1.4.1"
+local nemsio_ver=os.getenv("nemsio_ver") or "2.5.4"
+local wrf_io_ver=os.getenv("wrf_io_ver") or "1.2.0"
+local ncio_ver=os.getenv("ncio_ver") or "1.1.2"
+local crtm_ver=os.getenv("crtm_ver") or "2.4.0"
+local ncdiag_ver=os.getenv("ncdiag_ver") or "1.1.1"
+
+load("PrgEnv-intel")
+load("intel")
+load("craype")
+load("cray-mpich")
+load(pathJoin("cmake", cmake_ver))
+load(pathJoin("python", python_ver))
+load(pathJoin("prod_util", prod_util_ver))
+load(pathJoin("netcdf", netcdf_ver))
+load(pathJoin("bufr", bufr_ver))
+load(pathJoin("bacio", bacio_ver))
+load(pathJoin("w3emc", w3emc_ver))
+load(pathJoin("sp", sp_ver))
+load(pathJoin("ip", ip_ver))
+load(pathJoin("sigio", sigio_ver))
+load(pathJoin("sfcio", sfcio_ver))
+load(pathJoin("nemsio", nemsio_ver))
+load(pathJoin("wrf_io", wrf_io_ver))
+load(pathJoin("ncio", ncio_ver))
+load(pathJoin("crtm", crtm_ver))
+load(pathJoin("ncdiag",ncdiag_ver))
+
+pushenv("GSI_BINARY_SOURCE_DIR", "/lfs/h2/emc/global/noscrub/emc.global/FIX/fix/gsi/20230911")
+
+whatis("Description: GSI environment on WCOSS2 Acorn")
diff --git a/regression/regression_param.sh b/regression/regression_param.sh
index 209762569..34d5964d8 100755
--- a/regression/regression_param.sh
+++ b/regression/regression_param.sh
@@ -4,8 +4,8 @@ regtest=$1
 
 case $machine in
 
-	Hera)
-	   sub_cmd="sub_hera"
+    Hera)
+           sub_cmd="sub_hera"
            memnode=96
            numcore=40
     ;;
@@ -19,23 +19,28 @@ case $machine in
            memnode=512
            numcore=40
     ;;
-	Jet)
-	   sub_cmd="sub_jet"
+    Jet)
+           sub_cmd="sub_jet"
            memnode=96
            numcore=40
     ;;
-	Gaea)
-	   sub_cmd="sub_gaea"
+    Gaea)
+           sub_cmd="sub_gaea"
            memnode=251
            numcore=128
     ;;
-	wcoss2)
-	   sub_cmd="sub_wcoss2"
+    wcoss2)
+           sub_cmd="sub_wcoss2"
            memnode=512
            numcore=128
     ;;
-	Discover)
-	   sub_cmd="sub_discover"
+    acorn)
+           sub_cmd="sub_acorn"
+           memnode=512
+           numcore=128
+    ;;
+    Discover)
+       sub_cmd="sub_discover"
     ;;
     *) # EXIT out for unresolved machine
         echo "unknown $machine"
@@ -71,7 +76,7 @@ case $regtest in
         elif [[ "$machine" = "Gaea" ]]; then
            topts[1]="0:10:00" ; popts[1]="12/8/" ; ropts[1]="/1"
            topts[2]="0:10:00" ; popts[2]="12/10/" ; ropts[2]="/2"
-        elif [[ "$machine" = "wcoss2" ]]; then
+        elif [[ "$machine" = "wcoss2" || "$machine" = "acorn" ]]; then
            topts[1]="0:10:00" ; popts[1]="12/8/" ; ropts[1]="/1"
            topts[2]="0:10:00" ; popts[2]="12/10/" ; ropts[2]="/2"
         fi
@@ -101,7 +106,7 @@ case $regtest in
         elif [[ "$machine" = "Gaea" ]]; then
            topts[1]="0:15:00" ; popts[1]="64/1/"  ; ropts[1]="/1"
            topts[2]="0:15:00" ; popts[2]="128/2/"  ; ropts[2]="/1"
-        elif [[ "$machine" = "wcoss2" ]]; then
+        elif [[ "$machine" = "wcoss2" || "$machine" = "acorn" ]]; then
            topts[1]="0:15:00" ; popts[1]="64/1/" ; ropts[1]="/1"
            topts[2]="0:15:00" ; popts[2]="128/2/" ; ropts[2]="/1"
         fi
@@ -131,7 +136,7 @@ case $regtest in
         elif [[ "$machine" = "Gaea" ]]; then
            topts[1]="0:15:00" ; popts[1]="64/1/"  ; ropts[1]="/1"
            topts[2]="0:15:00" ; popts[2]="128/2/"  ; ropts[2]="/1"
-        elif [[ "$machine" = "wcoss2" ]]; then
+        elif [[ "$machine" = "wcoss2" || "$machine" = "acorn" ]]; then
            topts[1]="0:15:00" ; popts[1]="64/1/" ; ropts[1]="/1"
            topts[2]="0:15:00" ; popts[2]="128/2/" ; ropts[2]="/1"
         fi
@@ -160,7 +165,7 @@ case $regtest in
         elif [[ "$machine" = "Gaea" ]]; then
            topts[1]="0:15:00" ; popts[1]="64/1/"  ; ropts[1]="/1"
            topts[2]="0:15:00" ; popts[2]="128/2/"  ; ropts[2]="/1"
-        elif [[ "$machine" = "wcoss2" ]]; then
+        elif [[ "$machine" = "wcoss2" || "$machine" = "acorn" ]]; then
            topts[1]="0:15:00" ; popts[1]="64/1/" ; ropts[1]="/1"
            topts[2]="0:15:00" ; popts[2]="128/2/" ; ropts[2]="/1"
         fi
@@ -190,7 +195,7 @@ case $regtest in
         elif [[ "$machine" = "Gaea" ]]; then
            topts[1]="0:15:00" ; popts[1]="28/1/"  ; ropts[1]="/1"
            topts[2]="0:15:00" ; popts[2]="28/2/"  ; ropts[2]="/1"
-        elif [[ "$machine" = "wcoss2" ]]; then
+        elif [[ "$machine" = "wcoss2" || "$machine" = "acorn" ]]; then
            topts[1]="0:15:00" ; popts[1]="64/1/" ; ropts[1]="/1"
            topts[2]="0:15:00" ; popts[2]="64/2/" ; ropts[2]="/1"
         fi
@@ -220,7 +225,7 @@ case $regtest in
         elif [[ "$machine" = "Gaea" ]]; then
            topts[1]="0:30:00" ; popts[1]="14/8/"  ; ropts[1]="/1"
            topts[2]="0:30:00" ; popts[2]="14/14/"  ; ropts[2]="/1"
-        elif [[ "$machine" = "wcoss2" ]]; then
+        elif [[ "$machine" = "wcoss2" || "$machine" = "acorn" ]]; then
            topts[1]="0:30:00" ; popts[1]="14/8/" ; ropts[1]="/1"
            topts[2]="0:30:00" ; popts[2]="14/14/" ; ropts[2]="/2"
         fi
@@ -250,7 +255,7 @@ case $regtest in
         elif [[ "$machine" = "Gaea" ]]; then
            topts[1]="0:10:00" ; popts[1]="16/2/" ; ropts[1]="/1"
            topts[2]="0:10:00" ; popts[2]="16/4/" ; ropts[2]="/2"
-        elif [[ "$machine" = "wcoss2" ]]; then
+        elif [[ "$machine" = "wcoss2" || "$machine" = "acorn" ]]; then
            topts[1]="0:10:00" ; popts[1]="16/2/" ; ropts[1]="/1"
            topts[2]="0:10:00" ; popts[2]="16/4/" ; ropts[2]="/2"
         fi
@@ -316,7 +321,7 @@ elif [[ "$machine" = "Gaea" ]]; then
    export MPI_BUFS_PER_HOST=256
    export MPI_GROUP_MAX=256
    export APRUN="srun --export=ALL -n \$ntasks"
-elif [[ "$machine" = "wcoss2" ]]; then
+elif [[ "$machine" = "wcoss2" || "$machine" = "acorn" ]]; then
    export OMP_PLACES=cores
    export OMP_STACKSIZE=2G
    export FORT_BUFFERED=true
diff --git a/regression/regression_var.sh b/regression/regression_var.sh
index 4a2bc8587..d4e7d99aa 100755
--- a/regression/regression_var.sh
+++ b/regression/regression_var.sh
@@ -47,8 +47,12 @@ elif [[ -d /work ]]; then # Orion or Hercules
   else
     export machine="Orion"
   fi
-elif [[ -d /lfs/h2 ]]; then # wcoss2
-  export machine="wcoss2"
+elif [[ -d /lfs/h2 ]]; then # wcoss2 or acorn
+  if [[ $(hostname -f) =~ "alogin" ]]; then
+    export machine="acorn"
+  else
+    export machine="wcoss2"
+  fi
 fi
 echo "Running Regression Tests on '$machine'";
 
@@ -63,7 +67,7 @@ case $machine in
     export check_resource="no"
     export accnt="ufs-ard"
   ;;
-  wcoss2)
+  wcoss2 | acorn)
       export local_or_default="${local_or_default:-/lfs/h2/emc/da/noscrub/$LOGNAME}"
       if [ -d $local_or_default ]; then
           export noscrub="$local_or_default/noscrub"
diff --git a/ush/detect_machine.sh b/ush/detect_machine.sh
index 0beb937f7..e06775dbb 100755
--- a/ush/detect_machine.sh
+++ b/ush/detect_machine.sh
@@ -14,8 +14,8 @@
 # First detect w/ hostname
 case $(hostname -f) in
 
-  adecflow0[12].acorn.wcoss2.ncep.noaa.gov)  MACHINE_ID=acorn ;; ### acorn
-  alogin0[12].acorn.wcoss2.ncep.noaa.gov)    MACHINE_ID=acorn ;; ### acorn
+  adecflow0[1-3].acorn.wcoss2.ncep.noaa.gov)  MACHINE_ID=acorn ;; ### acorn
+  alogin0[1-3].acorn.wcoss2.ncep.noaa.gov)    MACHINE_ID=acorn ;; ### acorn
   clogin0[1-9].cactus.wcoss2.ncep.noaa.gov)  MACHINE_ID=wcoss2 ;; ### cactus01-9
   clogin10.cactus.wcoss2.ncep.noaa.gov)      MACHINE_ID=wcoss2 ;; ### cactus10
   dlogin0[1-9].dogwood.wcoss2.ncep.noaa.gov) MACHINE_ID=wcoss2 ;; ### dogwood01-9
diff --git a/ush/module-setup.sh b/ush/module-setup.sh
index 299e13aa4..41d0d7c65 100755
--- a/ush/module-setup.sh
+++ b/ush/module-setup.sh
@@ -40,6 +40,10 @@ elif [[ $MACHINE_ID = wcoss2 ]]; then
     # We are on WCOSS2
     module reset
 
+elif [[ $MACHINE_ID = acorn ]]; then
+    # We are on WCOSS2-Acorn
+    module reset
+
 elif [[ $MACHINE_ID = stampede* ]] ; then
     # We are on TACC Stampede
     if ( ! eval module help > /dev/null 2>&1 ) ; then
diff --git a/ush/sub_acorn b/ush/sub_acorn
new file mode 100755
index 000000000..ed0f74c7c
--- /dev/null
+++ b/ush/sub_acorn
@@ -0,0 +1,171 @@
+#!/bin/sh --login
+set -x
+echo "starting sub_acorn"
+usage="\
+Usage:  $0 [options] executable [args]
+      where the options are:
+      -a account        account (default: none)
+      -b binding        run smt binding or not (default:NO)
+      -d dirin          initial directory (default: cwd)
+      -e envars         copy comma-separated environment variables
+      -g group          group name
+      -i                append standard input to command file
+      -j jobname        specify jobname (default: executable basename)
+      -m machine        machine on which to run (default: current)
+      -n                write command file to stdout rather than submitting it
+      -o output         specify output file (default: jobname.out)
+      -p procs[/nodes[/ppreq]
+                        number of MPI tasks and optional nodes or Bblocking and
+                        ppreq option (N or S) (defaults: serial, Bunlimited, S)
+      -q queue[/qpreq]  queue name and optional requirement, e.g. dev/P
+                        (defaults: 1 if serial or dev if parallel and none)
+                        (queue 3 or 4 is dev or prod with twice tasks over ip)
+                        (options: P=parallel, B=bigmem, b=batch)
+      -r rmem[/rcpu]    resources memory and cpus/task (default: '1024 mb', 1)
+      -t timew          wall time limit in [[hh:]mm:]ss format (default: 900)
+      -u userid         userid to run under (default: self)
+      -v                verbose mode
+      -w when           when to run, in yyyymmddhh[mm], +hh[mm], thh[mm], or
+                        Thh[mm] (full, incremental, today or tomorrow) format
+                        (default: now)
+Function:  This command submits a job to the batch queue."
+subcmd="$*"
+stdin=NO
+nosub=NO
+account=""
+binding="NO"
+dirin=""
+envars=""
+group=""
+jobname=""
+machine=""
+output=""
+procs=0
+nodes=""
+ppreq=""
+queue=""
+qpreq=""
+rmem="1024"
+rcpu="1"
+timew="900"
+userid=""
+verbose=NO
+when=""
+while getopts a:b:d:e:g:ij:m:no:p:q:r:t:u:vw: opt;do
+  case $opt in
+    a) account="$OPTARG";;
+    b) binding="$OPTARG";;
+    d) dirin="$OPTARG";;
+    e) envars="$OPTARG";;
+    g) group="$OPTARG";;
+    i) stdin=YES;;
+    j) jobname=$OPTARG;;
+    m) machine="$OPTARG";;
+    n) nosub=YES;;
+    o) output=$OPTARG;;
+    p) procs=$(echo $OPTARG/|cut -d/ -f1);nodes=$(echo $OPTARG/|cut -d/ -f2);ppreq=$(echo $OPTARG/|cut -d/ -f3);;
+    q) queue=$(echo $OPTARG/|cut -d/ -f1);qpreq=$(echo $OPTARG/|cut -d/ -f2);;
+    r) rmem=$(echo $OPTARG/|cut -d/ -f1);rcpu=$(echo $OPTARG/|cut -d/ -f2);;
+    t) timew=$OPTARG;;
+    u) userid=$OPTARG;;
+    v) verbose=YES;;
+    w) when=$OPTARG;;
+    \?) echo $0: invalid option >&2;echo "$usage" >&2;exit 1;;
+  esac
+done
+shift $(($OPTIND-1))
+if [[ $# -eq 0 ]];then
+  echo $0: missing executable name >&2;echo "$usage" >&2;exit 1
+fi
+exec=$1
+if [[ ! -s $exec ]]&&which $exec >/dev/null 2>&1;then
+  exec=$(which $exec)
+fi
+shift
+args="$*"
+bn=$(basename $exec)
+export jobname=${jobname:-$bn}
+output=${output:-$jobname.out}
+myuser=$LOGNAME
+myhost=$(hostname)
+
+DATA=/lfs/h2/emc/stmp/$LOGNAME/tmp
+mkdir -p $DATA
+
+queue=${queue:-dev}
+timew=${timew:-01:20:00}
+task_node=${task_node:-$procs}
+size=$((nodes*task_node))
+envars=$envars
+threads=${rcpu:-1}
+ncpus=$((procs*threads))
+
+export TZ=GMT
+cfile=$DATA/sub$$
+> $cfile
+echo "#!/bin/bash"                         >> $cfile
+echo ""                                    >> $cfile
+echo "#PBS -o $output"                     >> $cfile
+echo "#PBS -N $jobname"                    >> $cfile
+echo "#PBS -q $queue"                      >> $cfile
+echo "#PBS -l walltime=$timew"             >> $cfile
+echo "#PBS -l select=$nodes:mpiprocs=$procs:ompthreads=$threads:ncpus=$ncpus"     >> $cfile
+echo "#PBS -l place=vscatter:exclhost"     >> $cfile
+echo "#PBS -j oe"                          >> $cfile
+echo "#PBS -A "$accnt                      >> $cfile
+
+echo "" >> $cfile
+echo "export OMP_NUM_THREADS=$threads"      >> $cfile
+echo "export ntasks=$(( $nodes * $procs ))" >> $cfile
+echo "export ppn=$procs"                    >> $cfile
+echo "export threads=$threads"              >> $cfile
+echo "" >> $cfile
+echo ". "$(awk '{ print $1, $2, $3, $4, $5, $6, $7, $8, $9 }' $regdir/regression_var.out)  >>$cfile
+echo "" >> $cfile
+
+echo "module reset"                         >> $cfile
+echo "module use $modulefiles"              >> $cfile
+echo "module load gsi_acorn.intel"               >> $cfile
+echo "module load envvar/1.0"               >> $cfile
+echo "module load cray-pals/1.2.2"          >> $cfile
+echo "module -t list 2>&1 | while read line;do module show $line 2>&1 | sed -n -e '2p';done | sort" >> $cfile
+echo "module avail" >> $cfile
+
+echo "" >> $cfile
+
+cat $exec >> $cfile
+
+if [[ $nosub = YES ]];then
+  cat $cfile
+  exit
+elif [[ $verbose = YES ]];then
+  set -x
+  cat $cfile
+fi
+
+if [[ $stdin = YES ]];then
+  cat
+fi >>$cfile
+if [[ $nosub = YES ]];then
+  cat $cfile
+  exit
+elif [[ $verbose = YES ]];then
+  set -x
+  cat $cfile
+fi
+qsub=${qsub:-qsub}
+
+ofile=$DATA/subout$$
+>$ofile
+chmod 777 $ofile
+$qsub -V $cfile >$ofile
+rc=$?
+cat $ofile
+if [[ -w $SUBLOG ]];then
+  jobn=$(grep -i submitted $ofile|head -n1|cut -d\" -f2)
+  date -u +"%Y%m%d%H%M%S : $subcmd : $jobn" >>$SUBLOG
+fi
+##rm $cfile $ofile
+##[[ $MKDATA = YES ]] && rmdir $DATA
+echo "ending sub_acorn"
+exit $rc