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---
license: mit
size_categories:
- 100B<n<1T
tags:
- Helio
- coronal-extrapolation
configs:
- config_name: default
default: true
data_files:
- split: train
path: "train.csv"
- split: validation
path: "validation.csv"
- split: test
path: "test.csv"
- split: leaky_validation
path: "leaky_validation.csv"
---
# Coronal Field Extrapolation Dataset
## Dataset Summary
This dataset contains spherical harmonic coefficients of the coronal magnetic potential generated by emulating the physics-based **ADAPT-WSA PFSS** (Potential Field Source Surface) code, driven by **SDO/HMI** solar magnetogram observations. The target spherical harmonic coefficients represent the magnetic potential between the photosphere and the source surface (set to 2.51 Rs).
Each file also contains additional variables from the WSA model output, such as:
- Photospheric polarity maps
- Open/closed field line masks
Because ADAPT-WSA is an ensemble model, data is included for all **12 realizations** (`R000` – `R011`) in the filenames. Spherical harmonic data are stored in FITS HDU index **3**, formatted as a `(2, 91, 91)` array. Each `(91, 91)` array is triangular, with unused elements left as zero. The dataset covers May 2010 to December 2024 and includes daily simulations, with splits designed for consistent training, validation, and testing across years.
## Supported Tasks and Applications
- **Surrogate modeling**: Training ML models to emulate ADAPT-WSA PFSS outputs
- **Coronal field reconstruction**: Predicting global magnetic field structure from photospheric inputs
- **Space weather forecasting**: Estimating open/closed field lines and solar wind connectivity
- **Physics emulation**: Foundation models replacing computationally expensive PFSS runs
## Data Structure
### Data Files
- `train.csv`: Instances from Feb 15 to Dec 31 in each year between 2010–2019
- `validation.csv`: Instances from Jan 15–28 of each year between 2010–2019
- `test.csv`: All instances from each year between 2020–2024
- `leaky_validation.csv`: Instances from Jan 1–14 and Jan 29–Feb 11 of each year between 2010–2019
Compressed simulation model outputs containing spherical harmonics are available in `data.tar.gz`. Individual files are stored in FITS format. There are 12 ensemble realizations per one timestamp. Each file includes:
- Spherical harmonic coefficients (HDU index 3)
- Photospheric polarity information
- Open/closed field masks
- The paths to realizations (`R000`–`R011`) are provided in above mentioned csv files.
### Features
- **Spherical Harmonics**: `(2, 91, 91)` triangular arrays
- Order: up to 90
- Normalization: Schmidt
## Dataset Details
| Field | Description |
|------------------------|---------------------------------------------|
| **Temporal Coverage** | May 13, 2010 – Dec 31, 2024 |
| **Data Format** | FITS |
| **Data Shape** | (2, 91, 91) per instance |
| **Data Size** | 5,347 instances * 12 realizations |
| **Cadence** | 1 day |
| **Total File Size** | ~36.2 GB (compressed) |
| **Size per file** | ~763 KB |
## Example Code (Python)
```python
from astropy.io import fits
import numpy as np
import torch
fits_file = fits.open("wsa_201005010800R000_ahmi.fits")
sph_data = fits_file[3].data.copy()
fits_file.close()
coefficients = torch.from_numpy(
np.array(
[
sph_data[0, :, :][np.triu_indices(sph_data.shape[1])],
sph_data[1, :, :][np.triu_indices(sph_data.shape[1])],
]
)
)
```
## Contact
Daniel da Silva, [[email protected]]([email protected])
![WSA Fields](wsa_fields.png "WSA Fields")