What is a Geomagnetic Disturbance?
A geomagnetic disturbance occurs when the Earth's magnetosphere is disrupted due to interactions with solar wind, leading to changes in magnetic field strength and plasma flow.
Figure 1: The solar wind interacts with Earth’s magnetosphere causing auroras.
When a CME enters the magnetosphere, it causes a Geomagnetic Storm
Figure 2: Interaction between a CME and Earth's Magnetosphere
Figure 2: Interaction between a CME and Earth's Magnetosphere
A major magnetic storm may block HF propagation (3–30 MHz) by modifying the distribution of free-electrons in the ionosphere.
The project "Understanding HF Propagation" provides a detailed overview and tutorials on HF propagation.