- Problem overview
- Data preparation
- Model training
- Model post-processing: create wrapper for the trained model to include any normalization and de-normalization
- Run hybrid E3SM MMF-NN-Emulator simulation
- Evaluation of hybrid simulation
The ultimate goal of training a ML model emulator (of the cloud-resolving model embedded in the E3SM-MMF climate simulator) using the ClimSim dataset is to couple it to the host E3SM climate simulator and evaluate the performance of such hybrid ML-physics simulation, e.g., whether the hybrid simulation can reproduce the statistics of the pure physics simulation. Here we use "online" to denote this task of performing and evaluating hybrid simulation, in contrast to the "offline" task in which we focus on training a ML model. Here we describe the entire workflow of training these baseline models, running and evaluating the hybrid simulation. We provided a few baseline models that we trained and optimized on the online task. These pretrained models include the MLP models and U-Net models from Stable Machine-Learning Parameterization paper.
Refer to the ClimSim-Online paper for more details on the online task overview and the Stable Machine-Learning Parameterization paper for more details on the example baseline models we provide.
We take the low-resolution dataset as example. Dowload either the Low-Resolution Real Geography or Low-Resolution Real Geography Expanded dataset from Hugging Face. The expanded version includes additional input features such as large-scale forcings and convection memory (previous steps state tendencies) that we used in our pretrained U-Net models (refer to this paper for more details).
Please don't use the current preprocessed Subsampled Low-Resolution Data which does not include cloud and wind tendencies in target variables. For online testing, we need the ML model to predict not only temperature and moisture tendencies but also these cloud and wind tendencies.
If you would like to work on the High-Resolution Dataset and also want to expand the input feature, you can follow this notebook which illustrates how we created the expanded input features from the original low-resolution dataset.
The raw data contains a large number of individual data files outputted at each E3SM model time step. We need to aggregate these individual files into a few files containing data array for efficient training.
Take our MLP baseline model (from the Stable Machine-Learning Parameterization paper) for example. Run the create_dataset_example_v2rh.ipynb notebook to prepare the input/output files for the MLP_v2rh model.
If you want to reproduce the U-Net models from Stable Machine-Learning Parameterization paper, run the create_dataset_example_v4.ipynb notebook to prepare the input/output files for the Unet_v4 model. Or run the create_dataset_example_v5.ipynb notebook to prepare the input/output files for the Unet_v5 model. 'v4' is the unconstrained U-Net, while 'v5' is the constrained U-Net, please refer to original paper for more details.
To be able to couple your trained NN model to E3SM seeminglessly, you need to be aware of the following requirements before training your NN model:
- Your NN model must be saved in TorchScript format. Converting a pytorch model into TorchScript is straightforward. Our training scripts include the code to save the model in TorchScript format. You can also refer to the Official Torchscript Documentation for more details.
- Your NN model's forward method should take an input tensor with shape (batch_size, num_input_features) and return an output tensor with shape (batch_size, num_output_features). The output feature dimension should have a length of
num_output_features = 368and contain the following variables in the same order as:'ptend_t', 'ptend_q0001', 'ptend_q0002', 'ptend_q0003', 'ptend_u', 'ptend_v', 'cam_out_NETSW', 'cam_out_FLWDS', 'cam_out_PRECSC', 'cam_out_PRECC', 'cam_out_SOLS', 'cam_out_SOLL', 'cam_out_SOLSD', 'cam_out_SOLLD'. The ptend variables are vertical profiles of tendencies of atmospheric states and have a length of 60.
We provide the training scripts under the online_testing/baseline_models/ directory. Under the folder of each baseline model, we provide the slurm scripts under the slurm folder to run the training job.
For example, to train the MLP model (with a huber loss and a 'step' lr scheduler), you can run the following command:
cd online_testing/baseline_models/MLP_v2rh/training/slurm/
sbatch v2rh_mlp_nonaggressive_cliprh_huber_step_3l_lr1em3.sbatchThe training will read in the default configuration arguments listed in training/conf/config_single.yaml. You need to change a few path argument in the config_single.yaml to the paths on your machine, or you can also overwrite those paths in the slurm job scripts. By default, the training slurm scripts requested to use 4 GPUs. You can change the number of GPUs in the slurm scripts.
The training requires to use the modulus library. We used the modulus container image for the training environment. You could download the latest version by following the instructions on modulus website. For reproducibility information, we used version nvcr.io/nvidia/modulus/modulus:24.01. If you don't want to use a container, you could also use
pip install nvidia-modulusto install on any system but we recommend the container for best results.
4 Model post-processing: create wrapper for the trained model to include any normalization and de-normalization
The E3SM MMF-NN-Emulator code expects the NN model to take un-normalized input features and output un-normalized output features. Notebooks provided in ./model_postprocessing directory show how to create a wrapper for our pretrained MLP and U-Net models to include pre/post-processing such as normalization and de-normalization inside the forward method of the TorchScript model.
For example, the v5_nn_wrapper.ipynb notebook shows how to create a wrapper for the U-Net model to read raw input features, calculate additional needed input features, normalize the input, clip input values, pass them to the U-Net model, de-normalize the output features, and apply the temperature-based liquid-ice cloud partitioning.
Please follow the instructions in the ClimSim-Online repository to set up the container environment and run the hybrid simulation.
Please check the NVlabs/E3SM MMF-NN-Emulator repository to learn about the configurations and namelist variables of the E3SM MMF-NN-Emulator version.
The notebooks in the ./evaluation directory show how to reproduce the plots in the Stable Machine-Learning Parameterization paper. Data required by these evaluation/visualization notebooks can be downloaded at Stable Machine-Learning Parameterization: Zenodo Data.
- Zeyuan Hu, Harvard University