How to Read a Schumann Spectrogram: Complete Field Guide
From the horizontal time axis to color-mapped amplitude, learn how to interpret daily Tomsk SOS spectrograms like a real space-weather analyst.
Understanding the Spectrogram
The spectrogram from the Tomsk Space Observing System is a 24-hour visual record of Earth's electromagnetic activity. The X-axis shows time (00:00–23:59 UTC), the Y-axis shows frequency (0–40 Hz).
Reading the Colors
Color intensity represents amplitude:
- Dark blue/black — low activity
- Yellow/orange — moderate activity
- White/gold — high-energy events
Identifying Harmonics
Look for horizontal lines at the fundamental and harmonic bands:
- SR1 — 7.83 Hz (fundamental mode)
- SR2 — 14.3 Hz (first harmonic)
- SR3 — 20.8 Hz (second harmonic)
Detecting Events
Vertical bright lines indicate sudden energy events caused by thunderstorms or geomagnetic disturbances. Learning to read these patterns allows you to track global electromagnetic activity in real-time.
Practical Tips
The Tomsk SOS website updates this spectrogram every 24 hours, providing an invaluable resource for monitoring Earth's resonant frequencies. Check it daily to observe trends and correlate with solar wind data.