Acronyms and abbreviations
Acronyms and abbreviations are a common sight in space weather bulletins and they can be confusing if you aren't familiar with them. On this page you will find a list of the most commonly used terms along with a short description.
| Short | Long | Description |
|---|---|---|
| ACE | Advanced Composition Explorer | Solar and space exploration spacecraft located at the Sun-Earth L1 point. Was the primary source of real time space weather data until DSCOVR took over in 2016. |
| AIA | Atmospheric Imaging Assembly | Instrument on the SDO spacecraft. Provides continuous full-disk observations of the solar chromosphere and corona in seven extreme ultraviolet channels. |
| AR | Active Region | Groups of sunspots indicated with a number. Also known as a sunspot region. |
| BBSO | Big Bear Solar Observatory | Solar observatory located in the USA that has telescopes and instruments specifically used for studying the activities and phenomena of the Sun. |
| CH | Coronal hole | Area on the Sun where magnetic field lines arch away from the Sun. This enables the solar wind to escape at a high speed and cause dark holes in the corona as seen on solar images. |
| CIR | Co-rotating Interaction Region | Term for the compressed boundary between the fast and slow solar wind in a high speed solar wind stream from persistent coronal holes over multiple solar rotations. |
| CME | Coronal mass ejection | Large cloud of solar plasma released into space due to an event on the Sun. |
| DSCOVR | Deep Space Climate Observatory | An earth observation and space weather spacecraft operated by NOAA located at the Sun-Earth L1 point. It is the primary source of real time solar wind and IMF data. |
| DSF | Disappearing Solar Filament | The disappearance of a solar filament channel often due to a collapse or eruption. |
| Dst | Disturbance storm time index | Indicates the strength of the ring current around Earth caused by solar protons and electrons. A negative Dst value means that Earth's magnetic field is weakened. Values of -50nT and lower are generally considered as geomagnetic storm conditions. |
| EIT | Extreme ultraviolet Imaging Telescope | Instrument on the SOHO spacecraft. Provides solar imagery in four different wavelengths. |
| EPAM | Electron, Proton, and Alpha Monitor | Instrument on the ACE spacecraft. Measures a broad range of energetic particles. |
| ESA | European Space Agency | European organization dedicated to the exploration of space. |
| EUV | Extreme ultraviolet | Electromagnetic radiation spanning from 124 nanometre down to 10 nanometre in the electromagnetic spectrum. |
| EVE | Extreme Ultraviolet Variability Experiment | Instrument package on the SDO spacecraft. |
| GFZ | GeoForschungsZentrum | GFZ German Research Centre for Geoscience is the national research center for Earth Sciences in Germany. |
| GOES | Geostationary Operational Environmental Satellite | Series of satellites in a geostationary orbit around Earth. |
| HSC | Heliospheric Current Sheet | Boundary where the polarity of the Sun's magnetic field changes from north to south. It's shape can be compared to a ballerina's skirt. |
| HF | High Frequency | Term used to describe radio waves with a wavelength between 3 and 30 MHz. |
| HMI | Helioseismic and Magnetic Imager | Instrument on the SDO spacecraft. |
| HSS | High Speed Stream | Stream of solar wind at a higher than average speed. Often used to define solar wind coming from a coronal hole. |
| IMF | Interplanetary Magnetic Field | Solar magnetic field carried by the solar wind among the planets of the Solar System. |
| IRIS | Interface Region Imaging Spectrograph | NASA solar observation spacecraft. |
| L1 | Lagrangian point 1 | Point in space between two celestial objects where the gravitational pull from the two objects is equal. Several space weather related satellites orbit the Sun-Earth L1 point. |
| LASCO | Large Angle and Spectrometric Coronagraph | Instrument on the SOHO spacecraft used to detect and study coronal mass ejections. |
| LMSAL | Lockheed Martin Solar and Astrophysics Laboratory | Part of Lockheed Martin which design, build, and operate solar and astrophysical observing instruments. |
| MDI | Michelson Doppler Imager | Instrument on the SOHO spacecraft. It is no longer in use. |
| MLSO | Mauna Loa Solar Observatory | A solar observatory located on the island of Hawaii in the United States of America. |
| NASA | National Aeronautics and Space Administration | American agency responsible for the civilian space program as well as aeronautics and aerospace research. |
| NOAA | National Oceanic and Atmospheric Administration | American scientific agency. The SWPC Forecast Center is jointly operated by NOAA and the USAF. |
| nT | nanoTesla | A unit of measurement of the strength of a magnetic field often used in space weather. |
| PFU | Particle flux unit | A unit of flux intensity. Number of particles registered per second, per square centimeter and per steradian. |
| PlasMag | Plasma Magnetometer Solar Weather Instrument | Three instruments on the DSCOVR spacecraft which measures the solar wind for space weather predictions. |
| PROBA2 | PRoject for OnBoard Autonomy 2 | ESA spacecraft that has two scientific instruments to observe the Sun. |
| SC | Solar Cycle | Approximate 11-year period of change in the Sun's activity where the polarity of the Sun's large-scale magnetic field flips. |
| SDO | Solar Dynamics Observatory | Solar observation spacecraft operated by NASA in a geosynchronous orbit around Earth. |
| SI | Sudden Impulse | A sudden impulse occurs when a coronal mass ejection from the Sun collides with Earth’s magnetosphere. This causes the ring current and the horizontal component of the magnetic field to increase. This increase appears as a sudden spike on terrestrial magnetometers. |
| SIDC | Solar Influences Data Analysis Center | European space weather services provider based in Belgium. |
| SIR | Stream Interaction Region | Term for the compressed boundary between the fast and slow solar wind in a high speed solar wind stream. |
| SOHO | Solar and Heliospheric Observatory | Solar observation spacecraft at the Sun-Earth L1 point. |
| SPE | Solar proton event | Also known as a proton storm. If the intensity of protons having an energy of at least 10 MeV is at least 10 pfu at geosynchronous altitudes, then it is categorized as a SPE. |
| SSBC | Solar Sector Boundary Crossing | Crossing of the Heliospheric Current Sheet resulting in a change in the orientation of the magnetic field of the solar wind. |
| SSC | Storm Sudden Commencement | An abrupt change in the northward (X) component of the geomagnetic field. It marks the beginning of a geomagnetic storm. |
| SSN | Smoothed Sunspot Number | Averaged sunspot number over a specific period. |
| STA | STEREO Ahead | Solar observation spacecraft operated by NASA in an orbit around the Sun. It orbits slightly faster around the Sun than Earth does. |
| STB | STEREO Behind | Solar observation spacecraft operated by NASA in an orbit around the Sun. It orbits slightly slower around the Sun than Earth does. |
| SUVI | Solar Ultraviolet Imager | Instrument on the GOES-16 satellite. This instrument observes the Sun in six different wavelengths in extreme ultraviolet. |
| SWPC | Space Weather Prediction Center | Service center that continually monitors and forecasts Earth's space environment. It is the official source of space weather alerts and warnings for the United States. |
| USAF | United States Air Force | Service branch of the United States Armed Forces. The SWPC Forecast Center is jointly operated by NOAA and the USAF. |
| UTC | Coordinated Universal Time | Primary time standard by which the world regulates clocks and time. |
| VHF | Very High Frequency | Term used to describe radio waves with a wavelength between 30 and 300 MHz. |
| VLF | Very Low Frequency | Term used to describe radio waves with a wavelength between 3 and 30 kHz. |
| XRS | Solar X-ray Sensor | Instrument on the GOES satellites used to measure X-ray output of the Sun. |
| Å | Ångström | Commonly used unit of length for wavelengths of electromagnetic radiation. 1 Ångström equals 10-10 metres, 0.1 nanometres or 100 picometres. |
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