Pc5 wave storms in Solar Cycle 23

Thes files contain lists of wave storms during solar cycle 23 (years 1996-2008). Wave storms mark the time periods of continuous, elevated Pc5 range ULF wave activity in the near-Earth space. For quantifying wave activity we use the ground-based Pc5 ULF index developed by Lipsanen et al. 2025 with the calculation script available in Zenodo and the corresponding data files from latitudes 60-70 available in Zenodo. We use the horizontal (H) component of the index. The MLT range 6-18 used for the wave storm calculations corresponds to the Earth’s dayside. The storm thresholds are defined from the distribution of the dayside Pc5 index in solar cycle 23: moderate threshold is the 80th percentile of the data (20.5 nT²) and intense threshold is the 95th percentile (111.5 nT²).

We define wave storms as follows:

• if the index stays above the moderate storm threshold for at least 4 hours, the interval will be considered a storm
• if there are data points exceeding the moderate storm threshold less than 1 hour away from the storm, the storm will extend to these data points
• if the index stays above the intense storm threshold for at least 4 hours, the storm will be considered an intense storm

The provided files contain the list of 1. all wave storms, 2. only moderate and 3. only intense wave storms. They list the start and end times of the storms, with one minute resolution.

Format:

YYYY-MM-DD    HH:MM:SS