juliensimon/auroral-electrojet-index

---
license: cc-by-4.0
pretty_name: "Auroral Electrojet (AE) Index"
language:
- en
description: "Hourly Auroral Electrojet (AE/AU/AL/AO) indices from WDC Kyoto — measures auroral zone magnetic activity driven by magnetospheric substorms."
task_categories:
- time-series-forecasting
- tabular-regression
tags:
- space
- geomagnetic
- auroral-electrojet
- ae-index
- space-weather
- kyoto
- open-data
- tabular-data
size_categories:
- 100K<n<1M
configs:
- config_name: default
data_files:
- split: train
path: data/ae_index.parquet
default: true
---

# Auroral Electrojet (AE) Index

*Part of the [Space Weather Datasets](https://huggingface.co/collections/juliensimon/space-weather-datasets-69c24cae98f1666f2101ca70) collection on Hugging Face.*


Hourly Auroral Electrojet indices from [WDC Kyoto](https://wdc.kugi.kyoto-u.ac.jp/aeasy/).
Covers **2021-01-01** to **2026-03-08** with **45,312** hourly readings.

## Dataset description

The AE index measures auroral zone magnetic activity caused by enhanced ionospheric
currents flowing in the auroral oval. It is derived from geomagnetic variations at
10-13 stations along the auroral zone. The AE family includes four indices:

- **AE** (Auroral Electrojet): overall auroral activity (AU - AL)
- **AU** (Auroral Upper): measures eastward electrojet intensity
- **AL** (Auroral Lower): measures westward electrojet intensity
- **AO** (Auroral Origin): baseline level (AU + AL) / 2

AE complements the Dst index (ring current) by specifically tracking substorm-driven
auroral activity, which is critical for high-latitude communications and power grids.

## Schema

| Column | Type | Description |
|--------|------|-------------|
| `datetime` | datetime | Observation time (UTC, hourly) |
| `ae_index` | int | AE value in nanotesla (nT) |
| `au_index` | int | AU value in nanotesla (nT) |
| `al_index` | int | AL value in nanotesla (nT), typically negative |
| `ao_index` | int | AO value in nanotesla (nT) |
| `quality` | string | Data quality: "provisional" or "realtime" |
| `is_active` | bool | True if AE >= 500 nT |
| `activity_level` | string | "quiet" (< 100), "moderate" (100-300), "active" (300-500), "minor_storm" (500-1000), "major_storm" (> 1000) |

## Quick stats

- **45,312** hourly readings (2021-01-01 to 2026-03-08)
- **4,260** active hours (AE >= 500 nT)
- Peak AE: **2597 nT**
- Data quality: 0 provisional, 45,312 realtime

## Usage

```python
from datasets import load_dataset

ds = load_dataset("juliensimon/auroral-electrojet-index", split="train")
df = ds.to_pandas()

# Substorm activity
active = df[df["ae_index"] >= 500].sort_values("ae_index", ascending=False)

# AE time series
df["year"] = df["datetime"].dt.year
annual = df.groupby("year")["ae_index"].mean()

# Compare AE with AL (westward electrojet drives substorms)
import matplotlib.pyplot as plt
storm = df[(df["datetime"] >= "2024-05-10") & (df["datetime"] <= "2024-05-15")]
plt.plot(storm["datetime"], storm["ae_index"], label="AE")
plt.plot(storm["datetime"], storm["al_index"], label="AL")
plt.legend(); plt.ylabel("nT"); plt.title("AE/AL during May 2024 storm")
```

## Data source

[WDC for Geomagnetism, Kyoto](https://wdc.kugi.kyoto-u.ac.jp/aeasy/). Two quality tiers:
- **Provisional**: Visually screened but not final
- **Real-time**: Quicklook values, may be revised

## Update schedule

Daily at 19:00 UTC via [GitHub Actions](https://github.com/juliensimon/space-datasets).

## Related datasets

- [dst-index](https://huggingface.co/datasets/juliensimon/dst-index) — Dst geomagnetic storm index (ring current)
- [space-weather-indices](https://huggingface.co/datasets/juliensimon/space-weather-indices) — Daily Kp, Ap, F10.7 indices
- [kp-index](https://huggingface.co/datasets/juliensimon/kp-index) — Kp geomagnetic index

## Pipeline

Source code: [juliensimon/space-datasets](https://github.com/juliensimon/space-datasets)

## Support

If you find this dataset useful, please give it a ❤️ on the [dataset page](https://huggingface.co/datasets/juliensimon/auroral-electrojet-index) and share feedback in the Community tab! Also consider giving a ⭐️ to the [space-datasets](https://github.com/juliensimon/space-datasets) repo.

## Citation

```bibtex
@dataset{auroral_electrojet_index,
author = {Simon, Julien},
title = {Auroral Electrojet (AE) Index},
year = {2026},
publisher = {Hugging Face},
url = {https://huggingface.co/datasets/juliensimon/auroral-electrojet-index}
}
```

### Data source

[WDC for Geomagnetism, Kyoto](https://wdc.kugi.kyoto-u.ac.jp/aeasy/)

## License

MIT (pipeline code). AE data: free for non-commercial use per WDC Kyoto terms.