#!/bin/bash
#SBATCH --job-name=rotate_era
#SBATCH --account=NS9081K
#SBATCH --time=02:00:00
#SBATCH --mem=16G
#SBATCH --ntasks=1
#SBATCH --cpus-per-task=1
#SBATCH --output=rotate_%j.out

module purge
module load NCO

# --- USER SETTINGS ---
GRIDFILE=${GRIDFILE:?must set GRIDFILE}
ERAFILE=${ERAFILE:?must set ERAFILE}
TMPFILE=${TMPFILE:?must set TMPFILE}

echo "GRIDFILE = $GRIDFILE"
echo "ERAFILE  = $ERAFILE"
echo "TMPFILE  = $TMPFILE"



# Create file with ANGLE only (fast!)
cp "$ERAFILE" "$TMPFILE"
ncks -v ANGLE "$GRIDFILE" "$TMPFILE"
ncap2 -O \
  -s  'U0=Uwind; V0=Vwind;
      Uwind = U0*cos(ANGLE) + V0*sin(ANGLE);
      Vwind = V0*cos(ANGLE) - U0*sin(ANGLE);' \
  "$TMPFILE" "$TMPFILE"