The solar wind is a fast-moving stream of charged particles (plasma) that emerges from the sun. It travels around the solar system, carrying with it the magnetic field of the sun. An illustration showing how the solar wind rearranges Earth's magnetosphere, compresses the magnetic field on the side facing the sun while elongating it on the opposite end.The solar wind is a major factor affecting the space environment around the Earth and other planets. On Earth it causes phenomena such as auroras, geomagnetic storms, and radiation belts.
What are Solar Proton Events?Solar Proton Events are defined as a flux (of protons with energies higher than 10MeV) greater than 10 particles cm-2 s-1 ster-1 (per centimeter-squared per second per steradian) for more than fifteen minutes. The protons travel along the extended magnetic field lines of the Sun, some making their way to the Earth. Proton Flux Scale (NOAA S-Scale classification) S-scale thresholds (10, 100, 1000, 10000, 100000 pfu), based upon values observed or expected on the primary GOES satellite. The ≥100 MeV products are based on a single flux threshold of 1 proton flux unit (pfu) = 1 proton/(cm² s sr). Proton Events ForecastsProton forecasts indicate the percent chance that a proton event may occur during the following three days. Proton events are associated with impacts on HF radio communication, satellite operations and can be biologically hazardous to astronauts or aircrew at high latitudes. Proton forecasts are daily probabilistic forecasts, ranging from 1% (0.01) to 99% (0.99), of the likelihood of greater than 10 MeV Proton Event occurring within the specified 24-hour day. Proton forecasts are part of the 3-day Forecast and Forecast Discussion products sent twice daily at 00 UTC and 12 UTC by the Space Weather Prediction Center. The event threshold for Proton Flux is 10 pfu (particle flux unit = particles / cm2-s-sr) at greater than 10 MeV as measured by the NOAA GOES spacecraft. The NOAA Space Weather Scale for Radiation Storms describes the effects that can be experienced as the result of elevated levels of radiation that occur when the numbers of energetic particles increase. Proton AlertsProton alerts indicate that a proton event is currently in progress. Proton events are associated with impacts on HF radio communication, satellite operations and can be biologically hazardous to astronauts or aircrew at high latitudes. Proton Alerts are disseminated when the Proton Flux is 10, 102, 103, 104 and 10 5 pfu (particle flux unit = particles / cm2-s-sr) at greater than 10 MeV as measured by the NOAA GOES spacecraft. A separate alert is issued when the Proton Flux is 1 pfu at greater than 100 MeV as measured by the NOAA GOES spacecraft. Proton Summaries are sent at the end of a significant flare event to notify customers of the maximum Proton Flux reached during the event. The NOAA Space Weather Scale for Radiation Storms describes the effects that can be experienced as the result of elevated levels of radiation that occur when the numbers of energetic particles increase.
Discover how the solar wind affets skywave propagation. The project "Understanding HF Propagation," focuses on skywave propagation, shows near-real-time indices and explains what the terms mean. |