Introduction to Space Weather

Solar Activity Geomagnetic Activity Space Weather Observations Space Weather Warning Information

Solar Activity

Solar Flare Coronal Mass Ejection
1. Solar Flare
A solar flare is a sudden release of the magnetic energy from the solar surface which is stored in magnetic lines of force of the solar atmosphere. Flares mainly occur at the sunspots. As the magnetic field in active regions around sunspots gets unstable, the structure of the magnetic field is collapsed and it is presumed that this causes the solar flare. Flares are often followed by a high energy proton emission and a coronal mass ejection. They produce a broad range of electromagnetic waves from radio waves to gamma rays, and X-rays are primarily used for observational data to classify the intensity of flares. Because flares emit electromagnetic waves, the primary hazard to space weather can be communications interference such as satellite communications disruption, aeronautical operational communications disruption, GPS signal reception interruption, and the like.
2. Solar Proton Event
When a solar flare occurs, high energy protons in the solar atmosphere can reach the Earth in several hours at a very high velocity. This is called €˜solar proton event€™. A part of protons which is ejected during solar flares presumably causes the solar proton event. An unusually strong solar flare tends to be accompanied by it. The primary hazard to space weather due to solar proton event can be the increase of radiation dose. When high energy protons are injected into polar regions through the Earth's upper atmosphere, it increases radiation dose in the vicinity of polar airways and can affect flight crew who mostly operate an aircraft to polar regions. Also, the polar orbiting satellite can be in danger of radiation exposure.
3. Coronal Mass Ejection (CME)
A coronal mass ejection is a massive release of solar material from the Sun’s surface in a short amount of time. The ejected solar material is the plasma that consists of electric charged particles including electrons and protons. A high speed coronal mass ejection can produce a shock wave at the front of it. The cause of this coronal mass ejection is thought to be originated from the unstable magnetic field and plasma above the solar surface. It has a larger variety of hazards to space weather than a solar flare does. For example, the shock wave created by coronal mass ejections affects the orbit of a satellite, making the satellite to malfunction, increases radiation dose in the vicinity of polar airways, and causes a magnetic storm.