# Building ACCESS-OM3 with WW3: Using Spack for Local Modifications of WW3

**URL:** <https://forum.access-hive.org.au/t/building-access-om3-with-ww3-using-spack-for-local-modifications-of-ww3/4291>\
**Category:** Waves\
**Created:** [11 March 2025 02:04 UTC](https://forum.access-hive.org.au/t/building-access-om3-with-ww3-using-spack-for-local-modifications-of-ww3/4291 "2025-03-11T02:04:54Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![ezhilsabareesh8](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.access-hive.org.au/ezhilsabareesh8/32/790_2.png) [@ezhilsabareesh8](https://forum.access-hive.org.au/u/ezhilsabareesh8)\
**Post date:** [11 March 2025 02:04 UTC](https://forum.access-hive.org.au/t/building-access-om3-with-ww3-using-spack-for-local-modifications-of-ww3/4291/1 "2025-03-11T02:04:54Z")

</div>

#### **Introduction**

This guide explains the steps to build ACCESS-OM3 2025.01.0 (0.4.0) from source using Spack, with a specific focus on modifying and rebuilding **WAVEWATCH III (WW3)**. If you need to make local modifications to WW3—such as tuning wave physics, or implementing new parameterizations—this guide will walk you through the process of building ACCESS-OM3 with your changes applied to WW3.

Note: These instructions are only for users modifying the ACCESS-OM3’s WW3 source code. If you want to use a prebuilt version, refer to the documentation [here](https://github.com/ACCESS-NRI/access-om3-wav-configs/blob/main/README.md)

#### **Prerequisites**

Before building ACCESS-OM3 with modifications to **WW3** , you need to set up **Spack** on your system. Follow these steps documented [here](https://access-hive.org.au/getting_started/spack/) to install and configure Spack on **Gadi**.

#### **Setting Up a Spack Development Environment for ACCESS-OM3 with WW3**

The following steps assume you are already inside the Spack installation directory:

```auto
cd /g/data/$PROJECT/$USER/spack/0.22

```

#### **1. Create a Development Directory for Spack**

First, create a new directory to manage your Spack development environment:

```auto
mkdir spack-dev
cd spack-dev/

```

#### **2. Clone the ACCESS-OM3 Spack Configuration Repository**

Clone the **ACCESS-OM3 repository** that contains Spack configuration files:

```auto
git clone git@github.com:ACCESS-NRI/ACCESS-OM3.git

```

⚠ **Note:** This repository contains the **Spack environment configuration** for ACCESS-OM3, **not** the actual model source code.

#### **3. Create a Separate Directory for WW3 Development**

Since we are focusing on modifying and rebuilding WW3, create a dedicated directory for WW3 development:

```auto
mkdir ww3-dev
cd ww3-dev

```

#### **4. Create and Activate a Spack Environment**

Use the **spack.yaml** file from the cloned ACCESS-OM3 repository to create a new Spack environment:

```auto
spack env create -d . ../ACCESS-OM3/spack.yaml
spack env activate .

```

### **Modifying and Building ACCESS-OM3 with a Custom WW3 Fork**

After setting up the Spack environment, follow these steps to modify and build **ACCESS-OM3** with your own WW3 fork.

* * *

#### **1. Clone the ACCESS-OM3 Model Repository**

Next, clone the **ACCESS-OM3 model source code** (which includes MOM6, CICE6, and WW3) into your working directory:

```bash
git clone git@github.com:COSIMA/access-om3.git access-om3-nuopc  
cd access-om3-nuopc/

```

* * *

#### **2. Update the WW3 Component to Use Your Fork**

1. **Create a fork** of the official WW3 repository:

2. **Edit `.gitmodules`** to point to your fork instead of the default WW3 repository:

3. **Save and close** the file.

* * *

#### **3. Initialize and Update Submodules**

After modifying `.gitmodules`, update the WW3 submodule:

```bash
git submodule update --init --recursive

```

* * *

#### **4. Register ACCESS-OM3 in Spack for Development**

Now, register the **access-om3-nuopc** source code in Spack:

```bash
cd ../
spack develop -p ./access-om3-nuopc/ access-om3-nuopc@git.0.4.0
spack develop access-om3@git.2025.01.0

```

* * *

#### **5. Concretize and Install Dependencies**

Force a fresh Spack concretization (dependency resolution) and install everything:

```bash
spack concretize -f --fresh

```

#### **Run Spack Install**

Execute the following command to build and install all dependencies:

```auto
spack install

```

⚠ **Note:** The installation process will take a long time, especially on the first run, as Spack compiles all required components from source, including **MOM6, CICE6, and WW3**.

### **Rebuilding ACCESS-OM3 After Modifying WW3**

Once you have **successfully installed ACCESS-OM3** , you may need to rebuild it after making changes to **WW3**. Follow these steps to **recompile and update** your modified version:

* * *

### **1. Enable Spack**

If you have opened a new terminal session or logged in again, first enable Spack:

```auto
cd /g/data/$PROJECT/$USER/spack/0.22
module purge
. spack-config/spack-enable.bash

```

* * *

### **2. Activate the Spack Environment**

Reactivate your Spack development environment before making modifications:

```auto
spack env activate ww3-dev

```

* * *

### **3. Modify WW3 Code**

Navigate to your **ACCESS-OM3 source directory** and make the necessary modifications to the WW3 component:

```auto
cd spack-dev/ww3-dev/access-om3-nuopc/WW3/WW3

```

Once done, save the changes and commit them (optional):

```auto
git add .
git commit -m "Relevant commit message that describes the changes made."

```

* * *

### **4. Rebuild ACCESS-OM3 with the Updated WW3**

Run **Spack install** to recompile the model with your changes:

```auto
spack install

```

⚠ **Note:** This step will only recompile components that were modified (i.e., WW3) and not rebuild everything from scratch.

* * *

### **Run the Model with the Updated WW3 Executable**

Once you have made changes to the WW3 codebase and rebuilt ACCESS-OM3, you will need to configure the model to use the updated executable. Here’s how to proceed:

### **1. Load the Latest Version of Payu**

```auto
module use /g/data/vk83/prerelease/modules && module load payu

```

### **2. Clone the `access-om3-wav-configs` Repository**

Clone the appropriate branch from the `access-om3-configs` repository. For example:

For the `dev-MCW_100km_jra_ryf` branch:

```auto
payu clone --branch dev-MCW_100km_jra_ryf git@github.com:ACCESS-NRI/access-om3-configs.git wav_config_ryf

```

For the `dev-MCW_100km_jra_iaf` branch:

```auto
payu clone --branch dev-MCW_100km_jra_iaf git@github.com:ACCESS-NRI/access-om3-configs.git wav_config_iaf

```

### **3. Update the Configuration**

Modify the `config.yaml` file to update the executable path and remove the default module:

1. **Find the `exe:` line and replace it with the locally built executable**

- The executable is usually located in:

```auto
/g/data/$PROJECT/$USER/spack/0.22/release/linux-rocky8-x86_64/intel-2021.10.0/access-om3-nuopc-***/bin/access-om3-MOM6-CICE6-WW3

```

- Update `config.yaml` in the `wav_config_*` directory accordingly:

```auto
exe: /g/data/$PROJECT/$USER/spack/0.22/release/linux-rocky8-x86_64/intel-2021.10.0/access-om3-nuopc-***/bin/access-om3-MOM6-CICE6-WW3

```

1. **Remove the `access-om3/2024.09.0` module**

- In the `modules:` section, remove the following line:

```auto
- access-om3/2024.09.0

```

### **Regenerating Input Files for WW3**

When modifying the WW3 code, you need to update the executable and ensure that the wave model uses the correct grid and restart files. After building WW3 with **Spack** , the next step is to regenerate key input parameter files (`mod_def.ww3`) and restart files (`restart.ww3`) using the updated executable.

This process involves:

1. Running `ww3_grid` to generate a new `mod_def.ww3` (grid input parameters).
2. Running `ww3_strt` to generate a new `restart.ww3` (restart conditions).
3. Updating `config.yaml` to use these new files.

* * *

### **Steps to Regenerate and Update WW3 Grid & Restart Files**

#### **1. Navigate to the WW3 Pre-Processing Directory**

Move to the `WW3_PreProc` directory inside the wave configuration folder:

```auto
cd /g/data/$PROJECT/$USER/wav_config_*/WW3_PreProc

```

* * *

#### **2. Generate the Grid Input Parameter File (`mod_def.ww3`)**

Run the `ww3_grid` executable to create `mod_def.ww3`:

```auto
/g/data/$PROJECT/$USER/spack/0.22/release/linux-rocky8-x86_64/intel-2021.10.0/access-om3-nuopc-***/bin/ww3_grid

```

This will generate the `mod_def.ww3` file in the `WW3_PreProc` directory.

* * *

#### **3. Generate the Restart File (`restart.ww3`)**

Run the `ww3_strt` executable to create `restart.ww3`:

```auto
/g/data/$PROJECT/$USER/spack/0.22/release/linux-rocky8-x86_64/intel-2021.10.0/access-om3-nuopc-***/bin/ww3_strt

```

This will generate the `restart.ww3` file in the `WW3_PreProc` directory.

* * *

#### **4. Update `config.yaml` to Use the New Files**

Modify `config.yaml` so the model picks up the newly generated files. Locate the following lines:

```auto
- /g/data/vk83/configurations/inputs/access-om3/ww3/initial_conditions/global.1deg/2024.04.18/restart.ww3
- /g/data/vk83/configurations/inputs/access-om3/ww3/mod_def/global.1deg/2024.04.18/mod_def.ww3

```

And replace them with:

```auto
- /g/data/$PROJECT/$USER/wav_config_*/WW3_PreProc/restart.ww3
- /g/data/$PROJECT/$USER/wav_config_*/WW3_PreProc/mod_def.ww3

```

* * *

#### **5. Verify and Proceed**

- Ensure `mod_def.ww3` and `restart.ww3` exist in `WW3_PreProc`.
- Confirm `config.yaml` reflects the updated paths.
- You can now proceed with running the model using:

```auto
payu sweep && payu run

```

You’ve successfully updated the **WW3 executables** and regenerated necessary input files for **ACCESS-OM3**. Ensure the correct executable and files are referenced in `config.yaml` before running the model with **payu**. This process keeps WW3 aligned with your modifications.