Geomagnetic storms are caused by disturbed solar activity that injects energy into Earth’s space environment, mainly via bursts of solar wind and magnetic field structures that interact with Earth’s magnetosphere. The key drivers are:
- Solar wind streams and magnetic fields: A sustained, high-speed solar wind carrying a southward-oriented interplanetary magnetic field (IMF) at the dayside of the magnetosphere transfers energy into the magnetosphere, intensifying currents and heating particles. This process drives the main phase of storms.
- Coronal mass ejections (CMEs): Large eruptions from the Sun release plasma and magnetic fields that, when directed toward Earth, can strongly compress the magnetosphere and inject energy, often triggering powerful geomagnetic storms.
- Interplanetary structures: Other solar wind features like corotating interaction regions (CIRs) and compressed back-to-back streams can also energize the magnetosphere and cause storms, though CMEs are typically associated with the more intense events.
- Magnetospheric and ionospheric responses: The increased energy strengthens ring currents, alters the radiation belts, heats the upper atmosphere (thermosphere), and can disrupt radio signals and GPS. These effects are manifestations of the storm’s main phase and its recovery.
Core sequence, in brief:
- Solar eruptions eject CMEs and/or generate fast solar wind streams with southward IMF.
- The solar wind interacts with Earth's magnetosphere, transferring energy and driving stronger currents, especially the ring current.
- The magnetosphere and ionosphere respond, producing geomagnetic disturbances on the ground and in space, with potential impacts on satellites, navigation, and communications.
If you’d like, I can summarize typical warning signs, indices used (like Dst, Kp, and SYM-H), and common effects by category (auroras, satellite drag, navigation issues) with concise bullet points.
