surya-bench-coronal-extrapolation

# 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])],
]
)
)
```

## License
This dataset is licensed under the Creative Commons Attribution 4.0 International (CC BY 4.0) License.

## Contact

Daniel da Silva, [[e-mail]]([e-mail])


# 日冕磁场外推数据集

## 数据集概述
本数据集包含通过基于物理的**ADAPT-WSA PFSS（势场源面，Potential Field Source Surface）**代码仿真得到的日冕磁势球谐系数（spherical harmonic coefficients），该仿真以**SDO/HMI**太阳磁图观测数据为驱动。目标球谐系数表征光球层与源面（设定为2.51倍太阳半径Rs）之间的磁势分布。
每个文件还包含WSA模型输出的附加变量，例如：
- 光球层极性图
- 开放/闭合磁力线掩膜

由于ADAPT-WSA为集成模型，文件名中包含了全部**12个集成成员（R000–R011）**的对应数据。球谐数据存储于FITS格式的HDU（Header Data Unit）索引**3**中，格式为`(2, 91, 91)`数组。每个`(91, 91)`数组为三角数组，未使用的元素以0填充。本数据集涵盖2010年5月至2024年12月的每日仿真数据，并按年份设计了统一的训练、验证与测试划分方案。

## 支持的任务与应用场景
- **代理建模**：训练机器学习模型以复刻ADAPT-WSA PFSS的输出结果
- **日冕磁场重建**：基于光球层输入数据预测全球磁场结构
- **空间天气预报**：估算开放/闭合磁力线分布及太阳风连通性
- **物理仿真**：使用基础模型替代计算成本高昂的PFSS仿真运行

## 数据结构
### 数据文件
- `train.csv`：2010–2019年每年2月15日至12月31日的样本
- `validation.csv`：2010–2019年每年1月15日至28日的样本
- `test.csv`：2020–2024年每年的全部样本
- `leaky_validation.csv`：2010–2019年每年1月1日至14日及1月29日至2月11日的样本

包含球谐数据的压缩仿真模型输出文件存储于`data.tar.gz`中，单个文件采用FITS格式存储。每个时间戳对应12个集成成员的结果。每个文件包含：
- 球谐系数（HDU索引3）
- 光球层极性信息
- 开放/闭合磁力线掩膜
上述CSV文件中已提供各集成成员（R000–R011）的文件路径。

### 特征项
- **球谐系数**：`(2, 91, 91)`三角数组
- 阶数：最高90阶
- 归一化方式：施密特（Schmidt）归一化

## 数据集详情

| 字段 | 描述 |
|------------------------|---------------------------------------------|
| **时间覆盖范围** | 2010年5月13日 – 2024年12月31日 |
| **数据格式** | FITS |
| **数据形状** | 单样本为`(2, 91, 91)`数组 |
| **样本总量** | 5,347个样本 × 12个集成成员 |
| **采样频率** | 每日1次 |
| **总文件大小（压缩后）** | 约36.2 GB |
| **单文件大小** | 约763 KB |

## Python示例代码
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])],
]
)
)

## 联系方式
Daniel da Silva, [[e-mail]]([e-mail])