E3SM atmospheric initial condition remap tool (model-to-model)

tools/remap_atmIC_m2m/README.md

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+# E3SM Initial Condition Remapping Workflow
+
+Remap E3SM atmospheric initial conditions from one grid to another with proper surface pressure adjustment for topography differences.
+
+## Quick Start
+
+### 1. Get the Scripts
+
+From E3SM repository:
+
+```bash
+# Clone or navigate to E3SM repository
+cd /path/to/E3SM/tools/remap_atmIC_m2m/
+cp -r . /path/to/your/working/directory/
+cd /path/to/your/working/directory/
+```
+
+Or download directly from:
+<https://github.com/E3SM-Project/E3SM/tree/master/tools/remap_atmIC_m2m/>
+
+Example files available at:
+<https://portal.nersc.gov/cfs/e3sm/tang30/remap_atmIC_m2m/>
+
+### 2. Prepare Input Files
+
+You need:
+
+- Source initial condition file: `${CASENAME}.eam.i.${TIMESTAMP}.nc`
+- ESMF remapping weights: `map_source_to_target.nc`
+- Source grid topography file
+- Target grid topography file  
+- Vertical coordinate template: `E3SM_vert_coor_L80.nc`
+
+### 3. Edit Configuration
+
+Edit `remap_atmIC_m2m.sh`:
+
+```bash
+CASENAME="v3.LR.historical_0091"
+TIMESTAMP="2015-01-01-00000"
+SOURCE_GRID="ne30np4"
+TARGET_GRID="northamericax4v1np4"
+GRID_LABEL="northamericax4v1pg2"
+```
+
+### 4. Run
+
+```bash
+./remap_atmIC_m2m.sh
+```
+
+Output: `${CASENAME}_mapped_${TARGET_GRID}-topoadj.eam.i.${TIMESTAMP}.nc`
+
+## Files
+
+- `remap_atmIC_m2m.sh` - Main workflow script
+- `adjust_ps_m2m.py` - Python script for PS adjustment
+- `README.md` - This file
+
+## What It Does
+
+1. **Horizontal remapping** - Maps IC from source to target grid
+2. **PS adjustment** - Adjusts surface pressure for topography differences
+3. **Vertical remapping** - Interpolates to new vertical coordinate
+4. **Cleanup** - Removes intermediate files (set `KEEP_INTERMEDIATE="yes"` to keep)
+
+## Configuration Options
+
+In `remap_atmIC_m2m.sh`:
+
+| Variable            | Description          | Example                    |
+|---------------------|----------------------|----------------------------|
+| `CASENAME`          | Case name            | `v3.LR.historical_0091`    |
+| `TIMESTAMP`         | Time stamp           | `2015-01-01-00000`         |
+| `SOURCE_GRID`       | Source grid          | `ne30np4`                  |
+| `TARGET_GRID`       | Target grid          | `northamericax4v1np4`      |
+| `GRID_LABEL`        | For file naming      | `northamericax4v1pg2`      |
+| `VERTICAL_LEVELS`   | Vertical levels      | `L80`                      |
+| `PHIS_VAR`          | PHIS variable name   | `PHIS_d`                   |
+| `KEEP_INTERMEDIATE` | Keep temp files      | `no` (default)             |
+
+## Requirements
+
+- E3SM unified environment
+- Python 3 with numpy, netCDF4
+- NCO tools (ncks, ncremap)
+
+Load E3SM unified environment:
+
+```bash
+source /global/common/software/e3sm/anaconda_envs/load_latest_e3sm_unified_pm-cpu.sh
+```