SWx acronyms

Original: 14 July 2021 ; Last update: 12 August 2025

Welcome to the STCE's space weather (SWx) acronym webpage! This non-exhaustive list of nearly 1800 acronyms is based on existing listings from the Space Weather Introductory Course (SWIC) and the STCE Annual Reports (2011-present), and further expanded with a few listings from publications and reviews. This page will be regularly updated. Feel free to send us (swec@stce.be) any acronym you may find relevant for this SWx acronym list.

A	B	C	D	E	F	G	H	I
J	K	L	M	N	O	P	Q	R
S	T	U	V	W	X	Y	Z	0α

A (1) Area ; (2) Article ; (3) Ampère ; (4): Mount Wilson : a magnetically unipolar sunspot group (alpha)

Å Ångström (0.1 nm or 10^-10 m)

aa, AA A 3-hour and daily geomagnetic index (nT) based on two antipodal stations (Canberra and Hartland)

AA Auroral Absorption

AAR Auroral Acceleration Region

AAS American Astronomical Society

aBG Above background

ABL Atmospheric Boundary Layer

ABOVE Array for Broadband Observations of VLF/ELF Emissions (Canada)

A/C Aircraft

Ac Corrected area (e.g. for line-of-sight)

ACCESS-A Australian Community Climate and Earth-System Simulator (version -A)

ACE Advanced Composition Explorer

ACFJ Australia, Canada, France and Japan consortium (PECASUS/ICAO)

ACM Asteroids, Comets and Meteors conference

ACRIM Active Cavity Radiometer Irradiance Monitor (SMM and other satellites)

ACSG Atmospheric Composition Sub Group

AC-VC Atmospheric Composition Virtual Constellation

ACVE Atmospheric Composition Validation and Evolution

A/D Analog-to-Digital

ADA Astronomical Data Analysis

ADEOS-2 Advanced Earth Observing Satellite 2 (aka Midori-2 ; failed 25 Oct 2003)

ADF Active Day Fraction

ADU Analog to Digital Units

AE Auroral Electrojet

A_e Effective Area

A-EFFORT Athens Effective Solar Flare Forecasting (NOA)

AERONET AErosol RObotic NETwork

AFB Air Force Base

AFFECTS Advanced Forecast For Ensuring Communications Through Space

AFRL Air Force Research Laboratory

AFS Arch Filament System

AFWA Air Force Weather Agency

AGACC Advanced exploitation of Ground based measurements Atmospheric Chemistry and Climate applications

AGGA Advanced GPS/Galileo ASIC

AGN Active Geodetic Network

AGU American Geophysical Union

AGW Acoustic Gravity Waves (drivers of TID)

AH-64 Apache military helicopter

AI Artificial Intelligence

AIA Atmospheric Imaging Assembly (SDO)

AIAA American Institute of Aeronautics and Astronautics

AIP American Institute of Physics

AIRS Atmospheric Infra-Red Sounder

AIT Austrian Institute of Technology

a_k, A_k Resp. a 3-hour and daily geomagnetic index for a specific station k, ranging from 0 (quiet) to 400 nT (extremely severe storm)

Al Aluminum

ALADIN Aire Limitée Adaptation Dynamique Développement International

ALARM multi-hAzard monitoring and earLy wARning systeM

ALARO ALADIN and AROME combined model

ALC Automatic LIDAR Ceilometer

ALF faint narrow-band radio bursts from sources propagating with velocities close to the local Alfvén velocity

AlGaN Aluminium gallium nitride

ALIS Auroral Large Imaging System

AlN Aluminum Nitride

ALTEA Anomalous Long Term Effects on Astronauts

ALTIUS Atmospheric Limb Tracker for Investigation of the Upcoming Stratosphere

AM Amplitude Modulation

AMRVAC Adaptive Mesh Refinement – Versatile Advection Code

AMS American Meteorological Society

AMTD Atmospheric Measurement Techniques Discussion

anaprop Anomalous Propagation

ANeMoS Athens Neutron Monitor Station

AOCS (1) Air Operations Control Station ; (2) Attitude and Orbit Control Subsystem

AOD Aerosol Optical Depth

AOGS Asia Oceania Geosciences Society

AOSWA Asia-Oceania Space Weather Alliance

a_p, A_p Resp. a 3-hour and daily global (planetary geomagnetic index, ranging from 0 (quiet) to 400 nT (extremely severe storm)

APEX Airborne Prism EXperiment

API Application Programming Interface

ApJ The Astrophysical Journal

APL Applied Physics Laboratory (JHU)

APOD Astronomy Picture of the Day (NASA)

AP-RASC Asia-Pacific Radio Science Conference

APS (1) Active Pixel Sensor (PROBA2 / SWAP) ; (2) American Physical Society

APSOLUTE APS Optimized for Low-noise and Ultraviolet Tests and Experiments

APV Approach with vertical guidance

APWC Antennas and Propagation in Wireless Communications

AR (1) Active Region ; (2) Annual Report

Ar Argon

ARASE Nickname of the ERG satellite (JAXA)

ARCAS Augmented Resolution Callisto Spectrometer

ARMAS Automated Radiation Measurements for Aerospace Safety program (NASA)

AROME Application de la Recherche à l'Opérationnel à Meso-Echelle

ARTEMIS Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun

ARTIST Automatic Real-Time Ionogram Scaler with True height (software)

ASCA Advanced Satellite for Cosmology and Astrophysics (aka ASTRO-D ; failed on 14 July 2000)

ASCII American Standard Code for Information Interchange

ASEC Applied Space Environments Conference

ASFC Australian Space Forecast Center (SWS)

ASGARD An educational space programme for schools (no acronym)

ASH Amateur Sterrenkundigen van Herentals

ASIC Application Specific Integrated Circuit

ASIMUT Atmospheric Spectra Inversion Modular Utility Tools (code; BIRA-IASB)

ASIS Auroral Spectrograph In Skibotn (Sweden)

Asl, ASL above sea level

ASOPOS Assessment of Standard Operating Procedures for OzoneSondes

ASOV Action Spécifique Observatoire Virtuel

ASPECS Advanced Solar Particle Event Casting System

ASPIICS Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun (Proba-3)

ASSA (1) Automatic Solar Synoptic Analyzer (KSWC) ; (2) Astronomical Society of South Australia

ASTERIX Absolute Solar-TErrestrial Radiation Imbalance eXplorer

ASTRA Atmospheric & Space Technology Research Associates

ASTRON Netherlands Institute for Radio Astronomy - Stichting Astronomisch Onderzoek in Nederland

ASU CAS Astronomical Institute of the Czech Academy of Sciences

AT-AP-RASC ATlantic / Asia-Pacific Radio SCience meeting

ATC Air Traffic Control

ATLAS Atmospheric Laboratory for Applications & Science

ATM (1) Air Traffic Management ; (2) Apollo Telescope Mount (SkyLab)

ATMDEN ATMospheric DENsity estimates of forecast and prior total density for atmopsheric drag calculation (UKMO)

ATMOS (1) Advances in Atmospheric Science and Applications ; (2) Atmospheric Science Conference (ESA)

AT-RASC Atlantic Radio Science meeting

AtRIS The Atmospheric Radiation Interaction Simulator

ATST Advanced Technology Solar Telescope (old name for DKIST ; NASA)

ATV Automated Transfer Vehicle

AU, au Astronomical Unit; about 150 million km

avg. average

AVIDOS Aviation Dosimetry (SL)

AVL ASIMUT-(V)LIDORT model (IASI)

AWACS Airborne early Warning And Control Station

AWARE Automated WARnings of Earth arrivals (DTU)

AWDA Automatic Whistler Detector and Analyzer

AWG Astronomy Working Group

AZA Auroral Zone Absorption

B (1) Magnetic field (strength) ; (2): Mount Wilson classification: a bipolar sunspot group with distinct magnetic polarities (beta)

B.RCLab Belgian Radiometric Characterization Laboratory

B.USOC Belgian User Support and Operation Center

B/G, B/Gr Background

B₀ Heliographic latitude of the central point of the solar disk (The range of B₀ is +7.23°)

BAMC - UKMHD British Applied Mathematics Colloquium UK Magnetohydrodynamics

BAS British Antarctic Survey

BASS2000 BAse de données Solaire Sol

BATSE Burst And Transient Source Experiment (CGRO)

BBC British Broadcasting Corporation

BBC-SWS Balkan, Black Sea, and Caspian Sea Regional Network on Space Weather Studies

BBSO Big Bear Solar Observatory (USA)

BDE Bidirectional beams of suprathermal (> 100 eV) electrons

BE Belgium

BeiDou Chinese GNSS

BELARE Belgian Antarctic Expeditions

BELSPO Belgian Science Policy Office

BeNELux Belgium, The Netherlands, and Luxembourg

BEPOM Belgian Photonics Online Meetup

BER Backscatter-to-Extinction Ratio

BESSY Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung

BE-WISSDOM Belgian Web Incessant Screening for SDO Mission

BEZA-com A networking project from BELSPO and its South African homologue NRF

BG Mount Wilson classification: a bipolar sunspot group with a complex magnetic configuration (beta-gamma)

BGD Mount Wilson classification: a bipolar sunspot group with a complex magnetic configuration and at least 1 delta structure (beta-gamma-delta)

BGS British Geological Survey

Bifrost MHD code for simulating stellar atmospheres (no acronym); the name of the rainbow bridge from Midgard (the realm of man) to Asgard (the realm of the gods)

BINA Belgo-Indian Network for Astronomy and Astrophysics

BIOSPHERE Metrology for Earth Biosphere: Cosmic rays, ultraviolet radiation and fragility of ozone shield (EURAMET)

BIPM Bureau International des Poids et Mesures

BIRA Koninklijk Belgisch Instituut voor Ruimte-Aëronomie

BIRA-IASB Royal Belgian Institute for Space Aeronomy

BISA Royal Belgian Institute for Space Aeronomy

BKG German Federal Agency for Cartography and Geodesy (Bundesamt für Kartographie und Geodäsie)

BLH Boundary Layer Height

BMD Ballistic Missile Defense

BNCAR Belgian National Committee on Antarctic Research

BNCGG Belgian National Committee on Geodesy and Geophysics

BOLD Blind to Optical Light Detectors

BOS Bolometric Oscillation Sensor

BPIM BIRA Plasmasphere-Ionosphere Model

bps bits per second

BRAIN-be Belgian Research Action through Interdisciplinary Networks (BELSPO)

BRAMS Belgian RAdio Meteor Stations

BRITEC Bringing Research into ThE Classroom

BSI Back-Side Illuminated

BSPM Belgian SWIFF Plasmasphere Model (BIRA-IASB)

BSS (International) Beacon Satellite Symposium

BUKS Belgium, UK, and Spain

Bz Component of the IMF perpendicular to the ecliptic (“north-south” component)

C Capacitor

c Speed of light

C/N₀ Carrier-to-Noise density (dB-Hz)

C/NOFS Communications/Navigation Outage Forecasting System

c₀ Speed of light in vacuum

C1, C2, C3 Coronagraphs of LASCO (SoHO)

Ca II H A blue line in the solar spectrum at 396.85 nm

Ca II K A blue line in the solar spectrum at 393.37 nm

CA COST Action (COST)

CAAPC Cercle d'Astronomes Amateurs du Pays de Charleroi

CACTus Computer Aided CME Tracking software

CaF₂ Calcium fluoride

CALLISTO Compound Astronomical Low frequency Low cost Instrument for Spectroscopy and Transportable Observatory

CAMS (1) Cameras for All sky Meteor Surveillance (Benelux) ; (2) Copernicus Atmosphere Monitoring Service

CAP Communicating Astronomy with the Public

CAS Chinese Academy of Sciences

CASSIS Coordination Action for the integration of Solar System Infrastructures and Science

CB Central Bureau (EPN)

CBH Cloud Base Height

CCD Charge-Coupled Device

CCDF Complementary Cumulative Distribution Function

C-class flare Common x-ray flare

CCMC Community Coordinated Modeling Center

CCOR Compact Coronagraph (GOES)

CCSOM Constraining CMEs and Shocks by Observations and Modelling

CCT Communautés de Compétences Techniques (CNES)

CDAW Coordinated data analysis web (NASA/GSFC)

CDS Coronal Diagnostic Spectrometer (SOHO)

CELIAS Charge, Element, and Isotope Analysis System (SOHO)

CEN Centre d'étude de l'énergie nucléaire

CEOS Committee on Earth Observation Satellites

CERES Clouds and Earth’s Radiant Energy System (radiometer)

CESPM China-Europe Solar Physics Meeting

CESRA Community of European Solar Radio Astronomers

CGRO Compton Gamma-Ray Observatory (NASA)

cgs Metric system based on the centimeter, the gram, and the second

CGU Canadian Geophysical Union

CH Coronal Hole

CH₄ Methane

CH₄TIR CH4 Thermal InfraRed

CHAIN Canadian High Arctic Ionospheric Network

CHAMP CHAllenging Minisatellite Payload

CHARM Contemporary physical challenges in Heliospheric and AstRophysical Models

CIMI Comprehensive Inner-Magnetosphere Ionosphere model (NASA/GSFC)

CIOMP Changchun Institute of Optics, fine Mechanics and Physics (China)

CINDI Coupled Ion-Neutral Dynamics Investigation

CIR Co-rotating Interaction Region

CIS Cluster Ion Spectrometry (Cluster)

CISM Center for Integrated Space Weather Modeling

CLIMSO Christian Latouche IMageurs SOlaires (suite of solar telescopes at Pic du Midi)

CLS Collecte Localisation Satellites (CNES)

Cluster ESA/NASA mission to study the Earth’s magnetosphere (no acronym)

CLW Coronal Loops Workshop

cm, cm², cm³ centimeter, square centimeter, cubic centimeter

CM Central Meridian

CMA China Meteorological Administration

CMD Central Meridian Distance

CME Coronal Mass Ejection

CMOS Complementary Metal-Oxide-Semiconductor

CMOSIS CMOS Image Sensor

CMP Central Meridian Passage

CmPA Centre for mathematical Plasma-Astrophysics (KUL)

CNES Centre national d'études spatiales (France)

CNN Convolutional Neural Network

CNRS Centre national de la recherche scientifique (France)

CNSS COMPASS Navigation Satellite System

Co. Cooperation

CO₂ Carbon Dioxide

Co60 Cobalt 60

COCONUT COolfluid COroNa UnsTructured (model)

CODE Center for Orbit Determination in Europe

co-Is co-investigators

COLAGE Congreso Latinoamericano de Geofísica Espacial

COMESEP COronal Mass Ejections and Solar Energetic Particles (Alert System)

CoMP Coronal Multi-channel Polarimeter

COMPTEL Compton Telescope (CGRO)

COMPASS Chinese navigation satellite system

COMPLIMENT COMetary Plasma Light InstruMENT (Comet Interceptor ; ESA)

CONUS Continental/Contiguous United States (Lower 48 states in USA with/without Alaska)

COPUOS COmmittee on the Peaceful Uses of Outer Space (UN)

COR (1/2) Coronagraph (Inner/Outer) onboard STEREO

CORDEX COordinated Regional Climate Downscaling Experiment

CORONAS Complex ORbital Observations Near-Earth of Activity of the Sun (series of Russian satellites)

CORS Continuously Operating Reference Stations (GNSS)

COSPAR COmmittee on SPAce Research

COST (European) COoperation in Science & Technology

COSTEP Comprehensive SupraThermal and Energetic Particle analyser (SOHO)

COTS Commercial off-the-shelf

COVID-19 Coronavirus disease 2019

CP Coronagraph/Polarimeter (SMM)

CPAESS Cooperative Programs for the Advancement of Earth System Science

CPCP Cross-Polar Cap Potential

CPD Coarse Pointing Device

CPG Centre de Physique du Globe (Geophysical center Dourbes)

CPPA Conference on Plasma Physics and Applications

CPSR Core Plasma Supply and Refilling (in Geospace)

CPU Central Processing Unit

CR Carrington Rotation

CRAF Committee on Radio Astronomy Frequencies

CRaTER Cosmic Ray Telescope for the Effects of Radiation (LRO ; NASA)

CRC (1) Control and Reporting Center ; (2) Cyclotron Research Centre (in Louvain-La-Neuve) ; (3) Consortium Russia-China (PECASUS/ICAO)

CRCM Comprehensive Ring Current Model (NASA/GSFC)

CRF Cosmic Ray Flux

CrIS Cross-track Infrared Sounder (Suomi National Polar-orbiting Partnership)

CRMSE Centred Root Mean Square Errors

CROM A type of pyrheliometer developed by D. Crommelynck (RMI)

CRRES Combined Release and Radiation Effects Satellite (NASA)

CSEM Center of Space Environment Modeling (Switzerland)

CSHKP Carmichael, Sturrock, Hirayama, Kopp and Pneuman (standard model for solar flares)

CSL Centre Spatial de Liège

CSPM Coimbra Solar Physics Meeting

CSWFC Canadian Space Weather Forecast Center

CTIM Coupled Thermosphere-Ionosphere Model

CTIPe Coupled Thermosphere-Ionosphere-Plasmasphere-electrodynamic model

CTM Continuum storm (radio)

CubeSat A small satellite measuring 10cm x 10cm x 10cm

CUSUM Cumulative sum

CVC Convective and Volcanic Clouds

CW Continuous Wave

CWS Cross-track Wind Sensor

D (1) Directivity of an antenna; (2) ionospheric layer ; (3) Mount Wilson classification: a suffix called that can be added to the other types (B, BG, G) in case of two opposite magnetic polarity umbrae that are less than 2° from each other within the same penumbra (delta).

D/SCI ESA Science Directorate

D/TEC ESA Technology, Engineering and Quality Directorate

D2D Digisonde-to-Digisonde

D3S Distributed Space weather Sensor System

DARA Davos Absolute RAdiometer (Proba-3)

DAU Data Acquisition Unit

dB (1) Decibel ; (2) change in magnetic field amplitude ; (3) Disparition Brusque (DSF)

dB FS Decibels relative to Full Scale

dB-Hz decibel-Hertz (bandwidth relative to 1 Hz)

dBi dB with reference to an isotropic antenna

dBm dB with reference to 1 mW

dBW Decibel Watt

dBZ decibels relative to Z (reflectivity)

DCBs Differential Code Biases

Dcx Corrected Dst (and Dxt) for non-storm component and extended until 1932

DEM Differential Emission Measure

DeMeLab Detector Measurements Laboratory (aka STCL)

DENSER DEeply uNderstanding Space weather (ESA)

DGPS Differential Global Positioning System

DH Decametric-Hectometric

DIARAD DIfferential Absolute RADiometer

DIAS Digital Upper Atmosphere Server

DICTAT Dielectric Internal Charging Threat Assessment Tool

DIDBase Digital Ionosonde network DataBase

Digisonde Digitally Integrating Goniometric IonoSONDE

DIGISUN A software application for digitization of scanned sunspot drawings

D_Iono Ionospheric delay

DKIST Daniel K. Inouye Solar Telescope (USA ; 4m aperture)

DLR Deutsches Zentrum für Luft- und Raumfahrt (German Aerospace Center)

dm, dm², dm³ decimeter, square decimeter, cubic decimeter

DMI Danish Meteorological Institute

DMSP Defense Meteorological Satellite Program

DMVTEC Daily Mean VTEC

DN Digital Number (pixel values not calibrated into physically meaningful units)

DNL Distant Neutral Line

DOI Digital Object Identifier

DONKI space weather Database Of Notifications, Knowledge, Information (CCMC)

DOP Dilution Of Precision

DOT Dutch Open Telescope (45cm aperture)

DOU Dourbes (Intermagnet)

DoY, DOY Day of Year

DPD Debrecen Photographic Data

DPM Data Processing Model

DPP Division of Plasma Physics (APS)

DPS (1) Division for Planetary Sciences (EPSC) ; (2) Digital Portable Sounder

DPS4D Digisonde-Portable-Sounder-4D

DPTIS Double-Probe and Topside Ionospheric Sounder

DR Dynamic Range

Dr. (US: Dr) Doctor

DRAO Dominion Radio Astrophysical Observatory (Canada)

D-RAP D-Region Absorption Predictions (NOAA/SWPC)

DRBS Dourbes (Belgium, NMDB)

DREAM.3D A Digital Representation Environment for the Analysis of Microstructure in 3D

DSCOVR Deep Space Climate Observatory

DSF Disappearing Solar Filament (H-alpha)

DSLP Dual Segmented Langmuir Probe (PROBA2)

DSN Deep Space Network

DSP Digital Signal Processing

Dst Disturbance Storm Time index; an hourly geomagnetic index (nT)

DSW Data Science Workshop

D_Tropo Tropospheric delay

DTU Technical University of Denmark

DUSTER Dust Study, Transport and Electrostatic Removal (for exploration missions)

Dxt Reconstructed and extended Dst index (up to 1932)

DYASTIMA Dynamic Atmospheric Shower Tracking Interactive Model Application

E (1) Electric field; (2) Electrical efficiency of an antenna; (3) Energy; (4) ionospheric layer; (5) East

e^- electron

E, E_- , E₊Energy, Ingoing energy, Outgoing energy

e.g. exempli gratia (example given)

E1, E5a Galileo frequencies: E1 = 1575.42 MHz , E5a = 1176.45 MHz

EBAF Energy Balanced And Filled

EC European Commission

ECA European Cockpit Association

e-Callisto extended Compact Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatory

ECC Electrochemical Concentration Cell

ECMWF European Centre for Medium-range Weather Forecasts

E-corona Emission corona (EUV)

ECS European CubeSat Symposium

ECSIM(-CYL) Energy Conserving Semi-Implicit Method (Cylindrical)

ECUVM European conference on solar UV monitoring

ECV Essential Climate Variable

ed. Edition

EDACs Error-detection-and-correction algorithms

EDAS EGNOS Data Access Service

EDID European Debris Impact Database (ESA)

EDP Electron Density Profile

EDRS-C European Data Relay System, Satellite-C

Eds. Editors

EEJ Equatorial ElectroJet current

EESC Equivalent Effective Stratospheric Chlorine

EFR Emerging Flux Region

EFW Electric Field and Waves instrument (Van Allen probes)

EGNOS European Geostationary Navigation Overlay Service (Galileo / Europe)

EGNSS European GNSS

EGRET Energetic Gamma Ray Experiment Telescope (CGRO)

EGU European Geosciences Union

E-GVAP EUMETNET GNSS water Vapour Programme

eHEROES Environment for Human Exploration and RObotic Experimentation in Space

EHF (1) Electron Heat Flux event ; (2) Extremely High Frequency (30-300 GHz)

EHIS Energetic Heavy Ion Sensor (GOES)

EIA Equatorial Ionization Anomaly

EIG Economic Interest Grouping

EIS (1) Extreme-Ultraviolet Imaging Spectrometer (Hinode) ; (2) European Ionosonde Service (NOA)

EISCAT European Incoherent SCATter scientific association

EIT Extreme ultraviolet Imaging Telescope (SOHO)

EIT-wave A coronal wave named after the EIT instrument

EIWG Earth ionosphere waveguide

ELF Extremely Low Frequency (3-30 Hz)

ELIS ELISabeth, Belgium station/receiver in Antarctica

EM (1) Electromagnetic (2) Engineering Model

EMBRACE Brazilian Studies and Monitoring of Space Weather

EMFISIS Electric and Magnetic Field Instrument Suit and Integrated Science (VAP)

EMIC ElectroMagnetic Ion Cyclotron

EMP Electromagnetic pulse

EMUF E-layer MUF (ionosphere)

ENEON European Network of Earth Observation Networks (H2020)

ENLIL Sumerian god of wind and storms (NOT an acronym)

ENTSO-E European Network of Transmission System Operators for Electricity

ENV Environnement atmosphérique et spatial (CNES)

ENVISAT Environmental Satellite (ESA)

EnVision ESA mission to Venus (no acronym)

EPAM Electron, Proton, and Alpha Monitor (ACE)

EPB Equatorial Plasma Bubble

EPCARD European Program Package for the Calculation of Aviation Route Doses

EPD Energetic Particle Detector (SolO)

EPEAD Energetic Proton Electron and Alpha Detector (GOES / SEM)

EPN (1) EUREF Permanent Network (2) Europlanet

EPOS(-PL) European Plate Observing System (- Poland)

EPOS-IP European Plate Observing System – Implementation Phase

E-PROFILE EUMETNET Profiling Programme

EPS European Physical Society

EPSC European Planetary Science Congress

EPT Energetic Particle Telescope (PROBA-V)

EQE External Quantum Efficiency

ERA ECMWF re-analysis

ERAI , ERA5 ERA-Interim, 5^th ERA

ERA-Interim ECMWF Re-Analysis Interim

ERB(S) Earth Radiation Budget (Satellite)

ERG Exploration of energization and Radiation in Geospace (now called ARASE ; JAXA)

erg unit of energy (1 erg = 10⁻⁷ J)

ERNE Energetic and Relativistic Nuclei and Electron experiment (SOHO)

ES Earth System (Science and Environmental Management (COST)

Es Sporadic E (ionosphere)

ESA European Space Agency

ESAC European Space Astronomy Centre

ESC Expert Service Centre (ESA/SSA)

ESCAPE (1) European SpaceCraft for the study of Atmospheric Particle Escape ; (2) European Science Cluster of Astronomy & Particle physics ESFRI research infrastructures

ESD Electrostatic Discharge

ESERO European Space Education Resource Office

ESF Equatorial Spread F

ESFRI European Strategy Forum on Research Infrastructures

ESIO EUV Solar Imager for Operations

ESLAB ESRO Scientific and technical LABoratory

ESO European Southern Observatory

ESOC European Space Operations Centre

ESP (1) EUV SpectroPhotometer (SDO) ; (2) Energetic Storm Particle event

ESPAS European Strategy and Policy Analysis System (FP7)

ESPD European Solar Physics Division (EPS)

ESPM European Solar Physics Meeting

ESRIN European Space Research Institute

ESRO European Space Research Organisation

EST European Solar Telescope (4m aperture ; under construction)

ESTEC European Space Research and Technology Centre

E-SWAN European Space Weather and Space Climate Association

ESWC European Space Weather Community

ESWF Empirical Solar Wind Forecasting (Uni Graz)

ESWP European Space Weather Portal

ESWS European Space Weather Symposium (2020)

ESWW European Space Weather Week

et al. et alii (and other)

etc. et cetera (and so forth)

ETH Zürich Eidgenössische Technische Hochschule Zürich

ETRS European Terrestrial Reference System

EU European Union

EUCARA European Conference on Amateur Radio Astronomy

EUHFORIA European Heliospheric Forecasting Information Asset

EUI Extreme-Ultraviolet Imager (SolO)

EUMETNET European Meteorological services Network

EUMETSAT European Organization for the Exploitation of Meteorological Satellites

EUNADICS-AV European Natural Airborne Disaster Information and Coordination System for Aviation

EURAMET The European Association of National Metrology Institutes

EURAVIA European Association of Aerospace Students

EUREF EUropean Reference Frame

EURISGIC European Risk from Geomagnetically Induced Currents project (FP7)

EUV Extreme Ultraviolet

EUVI Extreme Ultraviolet Imager (STEREO/SECCHI; LGRRS)

EUVM EUV Monitor (MAVEN)

EUVS Extreme Ultraviolet Sensor (GOES)

EUVST EUV High-throughput Spectroscopic Telescope (Solar-C ; Jaxa)

eV electron volt (1 eV = 1.602 × 10^-19 joules)

EVA Extravehicular activity

EVE Extreme ultraviolet Variability Experiment (SDO)

EOVSA Expanded Owens Valley Solar Array (USA)

EWC Early Warning Capability

EXIS EUV and X-ray Irradiance Sensors (GOES)

ExoMars Exobiology on Mars (ESA, Roscosmos)

F Force

f frequency

F1, F2 Ionospheric layers

F_10.7 , F_{10.7 cm} Solar radio flux at 10.7 cm wavelength

F10.7P Proxy for F_{10.7 cm} solar radio flux (= (F10.7 + F10.7A)/2, with F10.7A the average over the previous 81 days

F₂ Main ionospheric layer

F₃₀ Solar radio flux at 30 cm wavelength

FAA Federal Aviation Administration

FAC Field Aligned Current

FADEC Full Authority Digital Engine Control

FAIR Findable, Accessible, Interoperable, and Re-usable

FAM First Attendees Meeting

FARSUN Findability and Accessibility of historical Raw SUnspot Numbers

FARWEST FAst Radiation diffusion with Waves ESTimator

FAS Frequency-Angular-Sounding

FC Faraday Cup (DSCOVR)

FCS Flat Crystal Spectrometer (SMM)

F-corona Fraunhofer corona (dust particles)

FD Forbush Decrease

Fe xvi Fifteen times ionized iron

Fe IX-X 8 respectively 9 times ionized iron

FFT Feature Finding Team

FHNW Fachhochschule Nordwestschweiz (University of Applied Sciences and Arts Northwestern Switzerland)

FIELDS Electromagnetic Fields Investigation (PSP)

FIG Fédération Internationale des Géometres (International Federation of Surveyors)

FIP First Ionization Potential

FITS Flexible Image Transport System

FLEPOS Flemish POsitioning Service

FLEXPART FLEXible PARTicle dispersion model

FLIP FLuid Implicit Particle

FLRW Field line random walk

FM (1) Flight Model ; (2) Frequency Modulation

FMI Finnish Meteorological Institute

FN False Negative

FNRS Fonds National de la Recherche Scientifique

f-number the ratio of the system's focal length to the diameter of the entrance pupil

foE Critical frequency E-layer

foEs Sporadic E critical frequency

foF1 Critical frequency F1-layer

foF2 Critical frequency F2-layer

ForMaL-SEP Prediction tool for the expected maximum proton flux levels for >10 MeV (DENSER)

ForMaL-Xrange Tool for the forecast of the hourly range of the ground-based magnetic field north component (DENSER)

FORMOSAT-2 From “Formosa” (Taiwan) and satellite (Taiwan)

FOT Frequency of Optimum Transmission (ionosphere)

FOV Field-Of-View

FP False Positive

FP7 Framework Programme 7 (EU)

FPA Focal Plane Assembly

FPGA Field-Programmable Gate Array

FReSWeD Future Research on Space Weather Drivers

FRi3D Model of a flux rope in 3D

FRS (1) Fondation pour la Recherche Stratégique ; (2) Fonds de la Recherche Scientifique

FS Forward shock

FSI Full Sun Imager (SolO/EUI)

FSL Fluid Science Laboratory

FSMT Fort Smith (Canada, NMDB)

FST Facility Science Team (ISS-SOLAR)

ft foot or feet (1 ft = 30,48 cm)

FTE (1) Fast Transit Event ; (2) Full-Time Equivalent

ftp file transfer protocol

FTS Fourier Transform Spectrometer

FU Frederick University

FUV Far Ultraviolet

FWC Full Well Capacity

FWHM Full Width at Half Maximum (telescope filter parameter)

FY3E FengYun: 5^th satellite in the 3^rd series of Chinese weather satellites

G (1) Gauss (1 G = 100.000 nT; 1 T = 10.000 G) ; (2) NOAA’s scale for geomagnetic storms; (3) Gain of an antenna ; (4): Mount Wilson classification: a complex sunspot group with magnetic polarities so irregularly distributed there’s no longer a bipolar structure present (gamma) ; (5) Gigabyte (10⁹ bytes)

g number of sunspot groups

G4SUW Geant4 Space Users Workshop

GAGAN GPS Aided GEO Augmented Navigation (India)

Gaia ESA satellite (no acronym)

Galileo European GNSS

GAMIT GPS Analysis at MIT

GaN Gallium nitride

GASS General Assembly and Scientific Symposium

GAW Global Atmospheric Watch (WMO)

GB Gigabyte (10⁹ bytes)

GBAS Ground Based Augmentation System

GBO Ground-Based Observatory

GCOS Global Climate Observing System

GCR Galactic Cosmic Rays

GCS Graduated Cylindrical Shell

GDM-TEC Global daily mean Total Electron Content

GEANT-4 GEometry ANd Tracking (simulation platform)

GEEO Global Environmental Earth Observation

GEN General Data Service (SN-I)

GEO Geostationary Earth Orbit , i.e. a circular geosynchronous orbit 35.786 km in altitude

GEONET GNSS/GPS Earth Observation NETwork system

GeodesyML Geodesy Markup Language

GEOSS Global Earth Observation System of Systems

GERB Geostationary Earth Radiation Budget (radiometer)

GeV Giga electronvolt (10⁹ . 1.6 . 10^-19 Joule)

GF Geometric-Free

Gfg²GNSS for GEEO and GEOSS

GFZ Deutsches GeoForschungsZentrum (German Research Centre for Geosciences)

GHOST name of WG5 of the TOSCA project (no acronym)

GHz Gigahertz (10⁹ Hz)

GIC Geomagnetically induced current

GIE Geomagnetically induced Electric field

GIM Global Ionospheric Mapping

GIOVE Galileo In-Orbit Validation Element

GIRO Global Ionosphere Radio Observatory

GTIM Global ionosphere Thermosphere Model

GLASS GNSS Linkage Advanced Software System

GLE Ground Level Enhancement

GLONASS GLObal NAvigation Satellite System (Russia)

GMAC Global Monitoring Annual Conference

GmbH Gesellschaft mit beschränkter Haftung (Company with limited liability)

GMC Geostationary Magnetopause Crossing

GMDSS Global Maritime Distress and Safety System

GML Global Monitoring Laboratory

GMS Geomagnetic Storm

GNSS Global Navigation Satellite System

GNSS(GRE) GNSS corrections based on GPS-GLONASS-GALILEO constellations (GPS/Russia/Europe)

GNSS4SWEC Advanced GNSS tropospheric products for the monitoring of Severe Weather Events and Climate

GNSS-MR GNSS multipath reflectometry

G-nut/Tefnut Software library for GNSS data

GOES Geostationary Operational Environmental Satellite

GOLF Global Oscillation at Low Frequency (SOHO)

GOME Global Ozone Monitoring experiment (SCIAMACHY)

GOMESCIA GOME/SCIAMACHY/GOME-2

GONG Global Oscillation Network Group

GOP Geodetic Observatory Pecný

GP-B Gravity Probe B (2004-2010)

GPI GNSS Performance Indicators

GPS Global Positioning System (USA)

GRAPE GNSS Research and Application for Polar Environment

GRAS GNSS Receiver for Atmospheric Sounding

GRETSI Groupe d’Etudes du Traitement du Signal et des Images

GRUAN GCOS Reference Upper-Air Network

GRS Gamma-Ray Spectrometer (SMM)

GSAC GPS Seamless Archive Centers

GSE Geocentric Solar Ecliptic (coordinate system)

GSEQ Geocentric Solar EQuatorial (coordinate system)

GSFC Goddard Space Flight Center

GSM (1) Global System for Mobile Communications (2) Geocentric Solar Magnetospheric (coordinate system)

GSO Geosynchronous orbit

GSSAC German Space Situational Awareness Center

GST Goode Solar Telescope (formerly known as NST ; BBSO)

GSTP General Support Technology Programme (ESA)

GTO Geostationary Transfer Orbit

GUI Graphical user interface

GUVI Global Ultraviolet Imager (TIMED)

Gy Gray (J/kg ; absorbed radiation dose)

h (1) hour ; (2) Planck’s constant (6.62607004 × 10^-34 m² kg / s)

H (1) Hydrogen ; (2) Heat flux

H₂ Molecular hydrogen

h’ virtual height (ionogram)

H2020 Horizon 2020; EU Research and Innovation program (2014 to 2020)

H₂O Water, water vapour

HAARP High Frequency Active Auroral Research Program

HAC Hvar Astrophysical Colloquium

H-alpha (Hα) A red visible spectral line at 656.28 nm created by Hydrogen

HAO High Altitude Observatory

HAPI Heliophysics Data Application Programming Interface (SWx timeline viewer of KNMI)

HaSTeNet H-alpha Solar flare patrol TElescopic NETwork

h_c Critical height

H-component Horizontal component of the MF

HCS Heliospheric Current Sheet

He, He II Helium, ionized Helium

HEGIFTOM Harmonization and Evaluation of Ground-based Instruments for Free Tropospheric Ozone Measurements

HEIDI Hot Electron and Ion Drift Integrator code (RC model)

HEK Heliophysics Events Knowledgebase

HELCATS HELiospheric Cataloguing, Analysis and Techniques Service

Helios 1, 2 Two joint German-American space missions in the 1970s (no acronym)

HELIOS HELmet streamers In the solar corona and their OScillations

HELSTOP Harmonization and Evaluation of Lower Stratospheric and Tropospheric Ozone Vertical Profiles

HEO High Earth Orbit (altitude > 35.786 km)

HEOS-1, -2 Highly Eccentric Orbit Satellite (ESA)

HESPERIA High Energy Solar Particle Events forecasting and Analysis project

HF High Frequency (3-30 MHz)

HF Com HF Communication

HF-INT HF Interferometry

HI (1) Neutral atomic Hydrogen ; (2) Heliospheric Imager (STEREO)

Hi-C High Resolution Coronal Imager

HILDCAA High-Intensity Long-Duration Continuous Auroral Activities

Hinode A JAXA/NASA solar mission : Solar-B satellite (“sunrise”)

HiSPAC HIgh level Space Policy Advisory Committee (ESA)

h_mF₂ peak electron density height of F₂-layer

HMI Heliospheric and Magnetic Imager (SDO)

HOME Advances in Homogenisation Methods of Climate Series: An Integrated Approach (COST)

HOP Hinode Operation Plan

HOSS Handbook of Space Security

hPa hectopascal (atmospheric pressure)

HPL Horizontal Protection Level (FAA)

Hpo A group of Kp-like indices, where "H" stands for half-hourly or hourly, "p" for planetary, and "o" for open-ended (GFZ Potsdam)

Hp30, Hp60 Two varieties of the Hpo index, based on the time resolution: Hp30 concerns a 30-minute time interval, and Hp60 a 60-minute time interval (GFZ Potsdam)

HPS Heliospheric Plasma Sheet

HQ Headquarters

hr hour

HRI High-Resolution Imager (SolO/EUI)

HRIEUV High Resolution Imager in the EUV (SolO/EUI)

HRILYA High Resolution Imager in Ly-a (SolO/EUI)

HSF Human Space Flight (SN-I)

HSRS Humain Solar Radio Spectrograph

HSS High Speed Stream

HUJO HUmanistische JOngeren

HuRAS Humain Radio Astronomy Station

HWM Horizontal Wind Model

HWP Half Wave Plate

HXIS Hard X-ray Imaging Spectrometer (SMM)

HXR Hard X-Rays

HXRBS HXR Burst Spectrometer (SMM)

HXT Hard X-ray Telescope (Yohkoh)

HyMeX HYdrological cycle in the Mediterranean EXperiment

Hz Hertz (per second)

I (1) Intensity ; (2) Current

i (1) ion(s) ; (2) The index in a counter or series

i.e. “id est” (that is)

I/Ps Ionosphere-Plasmasphere system

IAASARS Institute for Astronomy, Astrophysics, Space Applications & Remote Sensing (NOA)

IABG Industrieanlagen-Betriebsgesellschaft mbH (German company; Proba-3)

IAC International Astronautical Congress

IAG International Association of Geodesy

IAGA International Association of Geomagnetism and Aeronomy

IAGOS In-service Aircraft for a Global Observing System (MOZAIC)

IAIN International Association of Institutes of Navigation

IAM Institute of Aerospace Medicine (DLR)

IAMAS International Association of Meteorology and Atmospheric Sciences

IAP Interuniversity Attraction Pole

IAPSO International Association for the Physical Sciences of the Oceans

IAS Institut d'Astrophysique Spatiale (France)

IASB Institut royal d’Aéronomie Spatiale de Belgique

IASC International Arctic Science Committee

IASI Infrared Atmospheric Sounding Interferometer

IASPEI International Association of Seismology and Physics of the Earth's Interior

IAU International Astronomical Union

IAUS IAU Symposium

IAW Inertial Alfvén Waves

IBUKS India, Belgium, UK, and Spain

ICAC International Conference on Aerosol Cycle

iCACGP international Commission on Atmospheric Chemistry and Global Pollution

ICAO International Civil Aviation Organization

ICARUS a new inner heliospheric model for the simulation of a steady background solar wind and the propagation and evolution of superposed CMEs (KUL; no acronym)

ICCC Inter-Commission Committee on "Geodesy for Climate Research" (IAG)

ICEAA International Conference on Electromagnetics in Advanced Applications

IceCON Constraining Ice Mass Change in Antarctica

ICMA International Commission on the Middle Atmosphere

ICEM International Conference on Electronic Materials

ICG International Committee on GNSS

ICIP International Conference on Image Processing

ICME Interplanetary CME

ICNS (1) Integrated Communications Navigation and Surveillance (conference) ; (2) International Conferencing and Networking Solutions

ICNSP International Conference on Numerical Simulation of Plasmas

ICON ICOsahedral Nonhydrostatic (meteorological model)

ICRC International Cosmic Ray Conference

ICSO International Conference on Space Optics

ICSU International Council for Science

ICT Information and Communication Technologies

ICTSW Interprogramme Coordination Team on Space Weather (WMO)

IDL Interactive Data Language

IDM Internal Discharge Monitor (CRRES)

IEEE Institute of Electrical and Electronics Engineers

IEH-3 International Extreme Ultraviolet Hitchhiker-03

IERS International Earth Rotation and Reference Systems Service

IES (1) Imaging Electron Spectrometer (Cluster) ; (2) Ionospheric Effects Symposium

IF (1) Intermediate Frequency; (2) Interface

IFF Identification Friend or Foe

IFOV Instrument Field Of View

IGAC International Global Atmospheric Chemistry project

IGACO-O₃/UV Integrated Global Atmospheric Chemistry Observation - O₃/UV

IGS International GNSS Service

IGSO Inclined geosynchronous orbit

IGY International Geophysical Year (1957-1958)

IHDEA International Heliophysics Data Environment Alliance

IIFR Interpolated In-Field Referencing

ILWS International Living With a Star (Program)

IMAGE Imager for Magnetopause-to-Aurora Global Exploration

IMC (1) International Meteor Conference ; (2) Inner Magnetosphere Coupling

IMF Interplanetary Magnetic Field

IMO International Meteor Organization

IMPACT In-situ Measurements of Particles and CME Transients (STEREO)

IMPALAS Investigation of MagnetoPause Activity using Longitudinally-Aligned Satellites

IMPC Ionosphere Monitoring and Prediction Center (DLR)

INA Integrated Nonlinear Analysis

INAF Istituto Nazionale di Astrofisica (Italy)

INAOE Instituto Nacional de Astrofísica, Óptica y Electrónica - National Institute for Astrophysics, Optics and Electronics (Mexico)

INGV Istituto Nazionale di Geofisica e Vulcanologia (Italy)

INPE National Institute for Space Research (Brazil)

InSight Interior Exploration using Seismic Investigations, Geodesy and Heat Transport

INSPIRE (1) International Satellite Program in Research and Education (consortium of space universities) ; (2) Infrastructure for Spatial Information in the European Community (EU)

INTEGRAL INTErnational Gamma-Ray Astrophysics Laboratory

INTERMAGNET INTErnational Real-time MAGnetic Observatory NETwork

IOC International Ozone Commission

ION Institute Of Navigation

IOP Institute of Physics

IP Interplanetary

IPAG Institut de Planétologie et d'Astrophysique de Grenoble (France)

IPB Ionospheric Plasma Bubble

IPC (1) Industrial Policy Committee (ESA) ; (2) International Pyrheliometric Comparison

IPCC Intergovernmental Panel on Climate Change

IPE Ionosphere-Plasmasphere Electrodynamics

IPELS Interrelationship between Plasma Experiments in Laboratory and Space

IPEV Institut Polaire Français Paul-Émile Victor

IPF International Polar Foundation

IPIM IRAP Plasmasphere Ionosphere Model

IPP Ionospheric Piercing Point

IPS (1) Interplanetary Scintillation ; (2) Ionospheric Prediction Service (old SWS)

IPSL Institut Pierre-Simon Laplace

IPT-SWeISS Inter-Programme Team on Space Weather Information, Systems and Services (WMO)

IPY International Polar Year (most recent: 2007-2009)

IQR InterQuartile Range

IR Infrared

IRACON Inclusive Radio Communication Networks for 5G and beyond

IRAP Institut de Recherche en Astrophysique et Planétologie (France)

IRENE International Radiation Environment near Earth

IRF Institutet för rymdfysik / Swedish Institute of Space Physics

IRI International Reference Ionosphere

IRIS Interface Region Imaging Spectrograph (NASA)

IRM(B) Institut Royal Météorologique (de Belgique)

IRNSS Indian Regional Navigation Satellite System (Regional system; India)

Irr. (1) Irradiance ; (2) Irregular

IRSA Institut Royal pour Sourds et Aveugles (Brussels, Belgium)

IRSN Institut de Radioprotection et de Sûreté Nucléaire

IS⊙IS Integrated Science Investigation of the Sun (PSP)

ISAS Institute of Space and Astronautical Science (Japan)

ISBN International Standard Book Number

ISC (1) International Science Council; (2) International Steering Committee

ISEE International Sun-Earth Explorer program (ESA/NASA)

ISES International Space Environment Service

ISEST International Study of Earth-Affecting Solar Transients

ISIS International Satellites for Ionospheric Studies

ISN International Sunspot Number ( = k . (10 . g + s))

ISO International Organization for Standardization

iso-B lines Lines of equal magnetic field strength

iso-L lines Lines of equal L (see L*)

ISOON Improved Solar Observing Optical Network (USAF/AFWA)

ISROSES International Symposium on Recent Observations and Simulations of the Sun-Earth System

ISS International Space Station

ISS-a, -b Ionosphere Sounding Satellite (-a , -b ; Japan)

ISSI International Space Science Institute

ISSN International Standard Serial Number

ISSS (1) International School of Space Science; (2) International School/Symposium for Space Simulations

ISTP (1) International Symposium on Tropospheric Profiling ; (2) International Solar Terrestrial Program

ISU International Space University

ISUAL Imager of Sprites and Upper Atmospheric Lightning (FORMOSAT-2)

ISWAT International Space Weather Action Teams (COSPAR)

ISWI International Space Weather Initiative

IT Information Technology

ITRF International Terrestrial Reference Frame (IERS)

ITU International Telecommunication Union

IUAP Intra-University Attraction Pole network

IUGG International Union of Geodesy and Geophysics

IUMRS International Union of Materials Research Societies

IUWDS International URSIgram and World Days Service (previous name of ISES)

I-V Current-Voltage

IVOA International Virtual Observatory Alliance

IWV Integrated Water Vapour

J Joule

JAXA Japan Aerospace eXploration Agency

JBP Jet Bright Point

JGR Journal of Geophysical Research

JHU Johns Hopkins University

jHV jHelioViewer

JMG Joint Meteorological Group

JOREM Jupiter Radiation Environment and Effects Models and Mitigation

JOSIE Jülich Ozonesonde Intercomparison Experiment

JPEG Joint Photographic Experts Group

JSON JavaScript Object Notation

JSWSC Journal of Space Weather and Space Climate

JUICE JUpiter ICy moons Explorer

JWG Joint Working Group

K (1) Local K-index: A 3-hour geomagnetic index, ranging from 0 (quiet) to 9 (extremely severe storm) ; (2) degrees Kelvin

k wave number

K* Local 1-minute resolution K index

Ka-band “Kürz above”: Radio frequency band from 27-40 GHz

KAW Kinetic Alfvén Waves

K_BEL Local K index for Belgium

KBVE Koninklijke Belgische Vereniging der Elektrotechnici

K-Cor K-coronagraph (MLSO)

K-corona Kontinuierlich corona (electrons)

k-factor An observer-specific scaling factor used for the computation of the ISN

keV kilo electronvolt (10³ . 1.6 . 10^-19 Joule)

kHz kilo Hertz (10³ /second)

KI Potassium iodide

km, km² kilometer, square kilometer

km kilometer

km/s kilometers per second

KMI Koninklijk Meteorologisch Instituut

KNMI Koninklijk Nederlands Meteorologisch Instituut

KNVWS Koninklijke Nederlandse Vereniging voor Weer- en Sterrenkunde

KORTES KOronal X-Ray TElescope and Spectrometer (Russia ; ISS)

K_p "planetarische Kennziffer" or Planetary K-index; A 3-hour geomagnetic index, ranging from 0 (quiet) to 9 (extremely severe storm)

KPN Koninklijke PTT Nederland NV

KPNO Kitt Peak National Observatory (USA)

K_s Standardized K index

KSAW Klaus Sievers Aviation Weather

KSB Koninklijke Sterrenwacht van België

KSC Kagoshima Space Center (Japan)

KSO Kanzelhöhe Observatory for Solar and Environmental Research (Austria)

KSP Key Science Project

KSWC Korean Space Weather Center

KU K unit (geomagnetic)

KUL, KULeuven Katholieke Universiteit Leuven

kV kiloVolt (10³ Volt)

L (1) Letter (manuscript); (2) Length; (3) Loss ; (4) L-shell (see L*)

L* Set of Earth's magnetic field lines which cross the Earth's magnetic equator at * earth radii from the centre of the Earth (e.g. L = 2)

l/m² Liter per square meter

L₀ Heliographic longitude of the central point of the solar disk

L1, … , L5 First, … , fifth Lagrangian point

L1, L2 GPS frequencies: L1 = 1575.42 MHz, L2 = 1227.60 MHz

LAAS Local Area Augmentation System

LAC Local Analysis Centres (EPN)

LANL Los Alamos National Laboratory (USA)

LaRa Lander Radio science (ExoMars)

LaRC Langley Research Center

LASCO Large Angle Spectrometric Coronagraph (SOHO); small (C2) and wide (C3) field of view

LASP Laboratory for Atmospheric and Space Physics

Lat Latitude

LATMOS Laboratoire ATmosphères, Milieux, Observations Spatiales (France)

LAU LAUnch operations (SN-I)

LBL line-by-line

L-class Large class satellite (ESA)

LCS (1) Local Coronal Signature ; (2) Low-Coronal Signatures

LDE Long Duration Event

LDM-TEC Latitudinal Daily Mean TEC value

LEA Learmonth (RSTN, radio observatory)

LEMUR Large European Module for solar Ultraviolet Research

LEO Low Earth Orbit (160-2000 km altitude)

LEP Lightning induced Electron Precipitation

LET Linear Energy Transfer

LF Low Frequency (30-300 kHz)

LGRRS-EUVI LaGRange Remote Sensing instruments (EUVI)

LH Left-handed

LHCP Left Hand Circular Polarized

LIDAR LIght Detection And Radar

LIEDR Local Ionospheric Electron Density profile Reconstruction

LIF Light Ion radiation Facility (in Louvain-La-Neuve)

LLS Research Unit “Lasers and Spectroscopies” at the Université de Namur (Belgium)

LMSAL Lockheed Martin Solar and Astrophysics Laboratory

LOC Local Organizing Committee

LOFAR Low-Frequency Array

LOL Loss Of Lock (GNSS)

Lon Longitude

LORAN Long Range Navigation

LOS Line Of Sight

LOTUS Long-term Ozone Trends and Uncertainties in the Stratosphere

LOUI-Base Lowell ObliqUe Incidence database

LPV Localizer performance with vertical guidance

LPV-200 Localizer Performance with Vertical guidance until the aircraft is 200 ft above the runway

LRO Lunar Reconnaissance Orbiter (NASA)

LRSP Living Reviews in Solar Physics

Ls Solar longitude

LSWC Lund Space Weather Centre (Sweden)

L-shell Set of planetary magnetic field lines (see L*)

LSTID Large-Scale Traveling Ionospheric Disturbance

LT Local Time

LTI Lower thermosphere and ionosphere region

LTP Long-term planning (SolO)

LUCE LUnar CubeSats for Exploration

LUCI Lagrange eUv Coronal Imager (Lagrange)

LUF Lowest Usable Frequency

LUT LookUp tables

LVF Linear Variable Filter

LVNL Luchtverkeersleiding Nederland

LW Langmuir Wave

LWS Living With a Star

LYA Ly-α

LYRA Large Yield RAdiometer, formerly called Lyman Alpha Radiometer (PROBA2)

LYRAFF LYRA Flare Finder

Ly-α Lyman-alpha, a spectral line in the VUV at 121.6 nm

m, m², m³ Meter, square meter, cubic meter

M³G Metadata Management and distribution system for Multiple GNSS Networks

M2M Moon-to-Mars

MAARBLE Monitoring, Analyzing and Assessing Radiation Belt Loss and Energization

MAB Manhay (Intermagnet)

MACH Magnetic fields, Atmospheres, and the Connection to Habitability

MADAWG Modelling and Data analysis Working Group (SolO)

MAG Magnetometer instrument (ACE, DSCOVR, GOES, SolO)

MagEIS MAGnetic Electron Ion Spectrometer (Van Allen probes)

MAGION-5 A Czech subsatellite

MAJIS Moons And Jupiter Imaging Spectrometer (JUICE)

MAPLD Military and Aerospace Programmable Logic Devices

MAO Main Astronomical Observatory of National Academy of Science of Ukraine (conference)

MARECS-A Maritime European Communications Satellite (Failed March 1991)

MARIE Mars Radiation Experiment (Mars Odyssey ; failed during Halloween storms)

MARSIS Mars Advanced Radar for Subsurface and Ionosphere Sounding

MASC Magnetic Activity of the Solar Corona

MASTER Meteoroid and Space Debris Terrestrial Environment Reference

MAVEN Mars Atmosphere and Volatile EvolutioN (NASA)

MAX-DOAS Multi-axis differential optical absorption spectroscopy

MB Megabyte (10⁶ bytes)

mbar millibar

MC (1) Magnetic cloud ; (2) Management Committee

MCC Mission Control Centre

M-class flare Medium x-ray flare

M-class Medium class satellite (ESA)

MCM Management Committee Meeting

MDI Michelson Doppler Imager (SOHO)

MEDOC Multi-Experiment Data and Operations Centre

MEGS-A Multiple EUV Grating Spectrograph A (SDO) - No longer operational

MEGS-B Multiple EUV Grating Spectrograph B (SDO)

MEO Medium Earth orbit (2000 - <35.786 km altitude)

MER Mars Exploration Rover

MESSENGER Mercury, Surface, Space Environment, Geochemistry and Ranging mission

Meteosat Series of geostationary meteorological satellites operated by EUMETSAT

METIS Multi Element Telescope for Imaging and Spectroscopy (coronagraph onboard SolO)

METOC Meteorology and Oceanography

MetOffice Meteorological institute of the UK

MetOp Meteorological Operational satellite (ESA)

METRO MEteors TRajectories and Origins (BRAIN-be)

MeV Mega electronvolt (10⁶ . 1.6 . 10^-19 Joule)

MF (1) Medium frequency (300 kHz - 3 MHz); (2) Magnetic field

MgII singly ionized Magnesium

MH Millionths of a solar hemisphere (1 MH = ~ 3 million km²). Area Earth = ~167 MH

MHD Magnetohydrodynamics

MHF Medium High Frequency

MHKA Museum van Hedendaagse Kunst Antwerpen

MHz Megahertz (10⁶/s)

MImOSA Magnetic imaging of the outer solar atmosphere

MIT Massachusetts Institute of Technology

MJD Modified Julian Day

MK Million degrees Kelvin

mks Metric system based on the meter, kilogram, and second

ML Maximum Likelihood

MLE Maximum Likelihood Estimate

MLH Mixing Layer Height

ML-Helio Machine Learning in Heliophysics

MLP Multi-Layer Perceptron

MLSO Mauna Loa Solar Observatory (USA)

MLT Magnetic Local Time

Mm Megameter (10⁶ meter)

mm, mm² millimeter (10^-3 meter), square mm

mm/s millimeter per second

MMM Monthly Management Meeting (SIDC)

MMS Magnetospheric MultiScale mission (NASA ; 4 spacecraft)

MOC (1) Mission Operations Center; (2) Maintenance and Observations Center (PECASUS)

MOF Magneto-optical filter

MOMA Multi-wavelength Observations and Modelling of Aurora

MoMo Model of Mars Ionosphere

MOMSTER MObile Meteor STation for Education & outreach

MOOC Massive Open Online Courses

MOSWOC Met Office Space Weather Operations Centre (UK)

MOZAIC Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft

MP (1) Magnetopause ; (2) Materials, Physical and nanosciences (COST)

mph miles per hour

MPI Message Passing Interface

MPPC Max Planck-Princeton Center

MPS Max Planck Institute for Solar System Research

MPS-LO, -HI Magnetospheric Particle Sensor – LOw, HIgh energy range (GOES)

ms milliseconds (10^-3 seconds)

MSAS MTSAT Satellite Augmentation System (Japanese SBAS)

MSCS McIntosh Sunspot Classification Scheme

MSFC Marshall Space Flight Center (NASA)

MSM (1) Metal-Semiconductor-Metal ; (2) Magnetospheric Specification Model

MSSL Mullard Space Science Laboratory

MST Meudon Solar Tower (France)

MSTID Medium-Scale Traveling Ionospheric Disturbance

MSU Moscow State University

mSv millisievert (10^-3 J/kg ; dose equivalent radiation)

MTI Moving Target Indication

MTOF Mass Tome-of-Flight sensor (SOHO)

MTSAT Multifunctional Transport SATellite (Japan)

MUF, MUF3000 Maximum Usable Frequency, the maximum radio frequency that can be reflected by the ionosphere for a given distance of transmission e.g. 3000 km

MULTI-VP multiple-1D solar wind model (not an acronym)

MUSCA Multi-Utility Spacecraft Charging Analysis tool (JAXA)

MUV Mid Ultraviolet

mV milliVolt (10^-3 V)

mW milliWatt (10^-3 W)

Mw Moment magnitude (earthquake)

MWD Measurements While Drilling

MySQL My Structured Query Language

N (1) Density: particles per volume unit ; (2) North ; (3) Nitrogen

n neutral particles

N₂ Molecular nitrogen

N₂⁺ 1NG First Negative Group of ionized molecular nitrogen

N₂⁺ Ionized molecular nitrogen

N₂O Nitrous oxide (“laughing gas”)

nA nano-Ampère (10^-9 Ampère)

NAIRAS Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NASA/LaRC)

NAOJ National Astronomical Observatory of Japan

NARMAX Nonlinear AutoRegresssive Moving Average eXogenous model

NASA National Aeronautics and Space Administration

NASO Nepal Astronomical Society

NASU National Academy of Sciences of Ukraine

NatGeo National Geographic

NATO North Atlantic Treaty Organization

NAVIC NAVigation with Indian Constellation (Regional; Indian GNSS)

Nc, Ns, Ng the number of spots Ns, the number of groups Ng, and the composite Nc = Ns + 10Ng

NCAR National Center for Atmospheric Research

NCEI National Centers for Environmental Information

NDA Nançay Decameter Array

NDACC Network for the Detection of Atmospheric Composition Change

N_e (1) Electron density (e^-m^-3) ; (2) Number of electrons

Ne Neon

NEC Numerical Electromagnetic Code

NEMO Novel EIT wave Machine Observing

NENL Near-Earth Neutral Line

NEO Near Earth Objects

NeQuick Electron density Quick calculation model (ionospheric model)

Net-TIDE Pilot Network for Identification of Travelling Ionospheric Disturbances in Europe

NGDC National Geophysical Data Center (NOAA)

NGRM Next Generation Radiation Monitor (ESA)

NICT National Institute of Information and Communications Technology (SWFC Japan)

NIR Near IR

NISP NSO Integrated Synoptic Program

NIST National Institute for Science and Technology (USA)

NITRO Nitrogen Ion TRacing Observatory (ESA)

NLFFF Non-Linear Force-Free magnetic Field

NOSWE NOrwegian centre for Space WEather

NJIT New Jersey Institute of Technology

NL The Netherlands

nm nanometer (10^-9 meter)

NM Neutron Monitor

NMA Norwegian Mapping Authority

NMDB Neutron Monitor DataBase

N_mF₂ peak electron density of F₂-layer

NO, NO⁺ Nitric oxide, ionized NO

No. Number of

NO₂ Nitrogen dioxide

NOA National Observatory of Athens

NOAA National Oceanic and Atmospheric Administration (numbering of sunspots,...)

NOMAD Nadir and Occultation for MArs Discovery (ExoMars)

NORAD North American Aerospace Defense Command (USA)

NoRP Nobeyama Radio Polarimeter

NORS Demonstration Network Of ground-based Remote Sensing observations in support of the Copernicus Atmospheric Service (FP7)

NO_x Refers to NO and NO₂

NP Non-parametric test

NRCan Natural Resources Canada

NRF National Research Foundation (South-Africa)

NRH Nançay Radioheliograph

NRL Naval Research Laboratory (USA)

NRT Near Real Time

ns nanosecond (10^-9 second)

N-S North-South

n-SEU neutron induced SEU

NSF National Science Foundation (USA)

NSMC National Satellite Meteorology Center (China)

NSO (1) National Solar Observatory (USA) ; (2) Non-Space systems Operations (SN-I)

NSREC Nuclear & Space Radiation Effects Conference

NSSDC National Space Science Data Center

NST New Solar Telescope (former name of GST ; BBSO)

NSWP National Space Weather Program (USA)

nT nanotesla (10^-9 Tesla)

NTC Non-Thermal Continuum

NTRIP Networked Transport of RTCM via Internet Protocol

NUV Near Ultraviolet

NV/SA Naamloze Vennootschap / Société Anonyme

NVBM Nederlandse Vereniging ter Bevordering van de Meteorologie

NWC Northwest Cape of Australia

NWP Numerical Weather Prediction

NYRIA Network of Young Researchers in Instrumentation for Astronomy

O, O₂ , O⁺ Oxygen, molecular oxygen, ionized oxygen

O₃ Ozone

O3S Ozone (O₃) Sonde

O3S-DQA Ozonesonde - Data Quality Assessment

OACT Osservatorio Astrofisico di Catania / Catania Astrophysical Observatory

OBEE Outer belt electron enhancements

OD Onderdepartement

ODC On Duty Center (PECASUS)

ODS Ozone Depleting Substances

ODYN Open-Source Software Analysis Tool to Investigate Space Plasma Turbulence and Nonlinear DYNamics

OECD Organization for Economic Co-operation and Development

OGSE Optics Ground Support Equipment

OI Oblique Incidence

OIC Organization of Islamic Cooperation

OMI Ozone Monitoring Instrument

OML Orbital-Motion-Limited

OMNIweb No acronym ; from “omni” meaning various, all (solar wind database ; GSFC/SPDF)

Op Optical information (H-alpha classification)

OpenGGCM Open Geospace General Circulation Model (NOAA)

ORB Observatoire Royal de Belgique

ORFEES Observation Radio Fréquences pour l’Etude des Eruptions Solaires

OSCAR Observatories of the Solar Corona and Active Regions

OSO Orbiting Solar Observatories (8 satellites ; 1962-1989 ; NASA)

OSSE Oriented Scintillation Spectrometer Experiment (CGRO)

OSUC Observatoire des Sciences de l’Univers en region Centre-Val de Loire (France)

OTH Over The Horizon

OVATION Oval Variation, Assessment, Tracking, Intensity, and Online Nowcasting (Johns Hopkins University ; NOAA/SWPC)

OVRO Owens Valley Radio Observatory (USA)

OVSA Owens Valley Solar Array (USA)

P (1) The position angle between the geocentric north pole and the solar rotational north pole measured eastward from geocentric north. The range in P is +26.3° ; (2) Power

p⁺ proton

p-p chain proton-proton chain (energy production in the Sun and other stars)

P2SC PROBA2 Science Center

pA pico-Ampère (10^-12 Ampère)

PAL Palehua (RSTN, radio observatory)

PAMIR Portal to Atmospheric and Marine Information Resources (BRAIN-be)

PANDOCA Professional Aviation Dose Calculator model

PAR Phased Array Radar

PARADISE Particle Radiation Asset Directed at Interplanetary Space Exploration

PARAFOG Predictive Alert of RAdiation FOG

PAS Polish Academy of Sciences

PATH Particle Acceleration and Transport in the Heliosphere model

PB Petabyte (10¹⁵ bytes)

PBC Primary Backup-Center (PECASUS)

PbS Lead Sulfide

PC (1) Polar Cap; a dimensionless geomagnetic index based on a single near-pole station (one for each pole) ; (2) Personal Computer

PC1,…,5 Pulsation Continue (geomagnetic pulsations ; 1 thru 5 as a function of frequency)

PCA (1) Polar Cap Absorption ; (2) Principal Component Analysis

PCAF PCA forecast

PCB Printed Circuit Board

PCF Polar Crown Filament

PCO Phase Center Offset

PCTR Prominence-Corona Transition Region

PCV Phase Center Variation

PDF Probability Density Functions

PEA (1) Post-eruption arcade (2) Princess Elisabeth Antarctic

PECASUS Partnership for Excellence in Civil Aviation Space weather User Services (ICAO)

PEN Penticton (DRAO, radio flux)

PEP Post Event Prediction

PFRR Poker Flat Research Range

PFSS Potential Field Source Surface

pfu particle (proton) flux unit: the number of particles registered per second, per square cm, and per steradian (1 pfu = 1 particle / cm^-2s^-1sr^-1)

PhD Doctor of Philosophy

PHI Polarimetric and Helioseismic Imager (SolO)

PI Principal Investigator

PIC Particle -in-Cell

PICASSO PICo-satellite for Atmospheric and Space Science Observations

PIL Polarity Inversion Line (magnetic neutral line)

PITHIA-NRF Plasmasphere Ionosphere Thermosphere Integrated Research Environment and Access services: a Network of Research Facilities

PlasMag Plasma Magnetometer onboard DSCOVR to measure solar wind

PLASTIC Plasma and Suprathermal Ion Composition (STEREO)

PLATINUM PLAnetary plasma Turbulence and Intermittency - coupling with interplanetary transients from data analysis and NUmerical Modelling

PLIP Polar Lights Imaging Polarimeter

PMOD Physikalisch-Meteorologisches Observatorium Davos

PMT Photo Multiplier Tube

POES Polar Operational Environmental Satellite (NOAA, EUMETSAT)

POLENET POLar Earth observing NETwork

PoS, PotS Plane-of-the-Sky

POSKEN Positioning Knowledge Exchange Network

ppb parts per billion

PPEF Prompt Penetration Electric Field

ppm parts per million

PPP Precise Point Positioning (DGPS)

PREMOS PREcision MOnitoring Sensor

PRESTO (1) Fast warning message for important SWx events issued by a RWC (no acronym) ; (2) PREdictability of the Solar-Terrestrial cOupling (SCOSTEP)

PRF (1) Preliminary Report and Forecast of Solar Geophysical Data (the “Weekly”); (2) Pulse Repetition Frequency

PROBA PRoject for OnBoard Autonomy (series of ESA satellites)

PROBA-V PROBA-Vegetation

PROBE PROfiling the atmospheric Boundary layer at European scale (COST)

PRODEX PROgramme de Développement d'EXpériences scientifiques (ESA ; PROgrame for the Development of scientific EXperiments)

PROSPER PRObabilistic Solar Particle Event foRecasting model

ps picosecond (10^-12 second)

PSD Post-Storm Depression (of upper portion HF)

PSF Point Spread Function

PSP (1) Parker Solar Probe ; (2) Pipe-to-Soil Potential

PSR Primary Surveillance Radar

PSV Pipe-to-Soil Voltage

P_t Transmitted power

PTB Physikalish-Technische Bundesanstalt (Germany)

PTC Photon Transfer Curve

PWE Plasma Wave Experiment (ARASE)

PWOM Polar Wind Outflow Model

px pixel

PYRILIOS A campaign for NIR Sun irradiance measurement, campaign name based on 'Sun' and 'Fire' in Greek (no acronym)

Python Programming language (no acronym)

q Charge

Q Quantity (e.g. e^-, H₂O,...)

Q&A Questions and Answers

QA Quality Assurance

QB50 A network of 50 cubesats to be launched simultaneously (FP7)

QC Quality Control

QDC Quiet-Day Curve

QE Quantum Efficiency

QPP Quasi-periodic pulsation

QR-code Quick Response code

QS Quiet Sun

QZSS Quasi-Zenith Satellite System (Regional system; Japan)

R (1) Radius ; (2) NOAA’s scale for Radio Blackouts; (3) Range ; (4) Resistor

R&D Research and Development

R_⊙ Solar radius (696.000 km)

r² the square of the correlation coefficient

RAAF Royal Australian Air Force

RAC Radar Auroral Clutter

RACA Rencontre Astronomique Centre Ardenne

RAD International Conference on Radiation, Natural Sciences, Medicine, Engineering, Technology and Ecology

RADAR RAdio Detection And Ranging

RADECS RADiation Effects on Components and Systems

RadSEP SEP post-event analysis for aviation radiation exposure (DLR/IAM)

RadSPACE Radiation environment outside and inside the ISS (DLR/IAM)

RaD-X Radiation Dosimetry Experiment (NASA ; stratospheric balloon)

RAE Royal Academy of Engineering (UK)

RAL Rutherford Appleton Laboratory

RAM Ring-current Atmosphere interactions Model

RAM-SCB RAM with self-consistent magnetic equilibrium solver

RAPID Research with Adaptive Particle Imaging Detector (Cluster)

RAS Royal Astronomical Society

RB-FAN Radiation Belt Forecast And Nowcast

RBR Radio burst (fixed frequency)

RBSP Radiation Belt Storm Probes (now called the “Van Allen probes”)

RC Ring Current

RCAAM Research Center for Astronomy and Applied Mathematics (Academy of Athens)

RC circuit An electric circuit composed of resistors and capacitors

RC time The time constant (in seconds) of an RC circuit

RCM (1) Regional Climate Modelling ; (2) Rice Convection Model (magnetosphere)

RCM-E RCM magnetic Equilibrium (magnetosphere)

RCS Radar Cross Section

RDA Range-Doppler Algorithm

R_e , R_E Earth radius (6378 km)

REENOM Radiation Environment and Effects NOwcasts for the Moon

REFAG Reference Frames for Applications in Geosciences

ReLU Rectified Linear Unit

R-ESC Space Radiation ESC (SSCC)

ReSourCE Radio Sciences Research on AntarCtic AtmosphEre

REST REpresentational State Transfer

RF Radio Frequency

RFI Radio Frequency Interference

RGD Rarefied Gas Dynamics

RGO Royal Greenwich Observatory (UK)

RGP Réseau GNSS Permanent

RH Right-handed

RHCP Right Hand Circular Polarized

RHESSI Reuven Ramaty High Energy Solar Spectroscopic Imager

Ri International sunspot number (old)

RINEX Receiver Independent Exchange Format

Riometer Relative Ionospheric Opacity Meter (originally: Relative Ionospheric Opacity Meter for Extra-Terrestrial Emissions of Radio noise)

RISE Rotation and Interior Structure Experiment (InSight)

RMI(B) Royal Meteorological Institute (of Belgium)

RMI-DPS-4D RMI-Digital Portable Sounder-4D

RMOC Rosetta Mission Operations Centre

RMS (1) Root Mean Square ; (2) Radiation Monitoring System (ISS)

RMSE Root Mean Square Error

RO Radio Occultation

ROADMAP ROle and impAct of Dust and clouds in the Martian AtmosPhere

ROB Royal Observatory of Belgium

ROMA Rank-Ordered Multifractal Analysis

Roscosmos Russian Space Agency

ROT Rate of TEC change

ROTEC Rate of TEC

ROTI ROT index

RPW Radio and Plasma Waves (SolO)

RRL Radio Research Laboratory (old NICT ; Japan)

RRR Rolling Requirement Review; WMO system for recording space weather requirements

RS (1) Reverse shock (2) Radiosonde

Rs Solar radius/radii

RSP Sweep-frequency radio burst

RSSB Royal Statistical Society of Belgium

RSTN Radio Solar Telescope Network (USAF)

R_sun Solar radius (~ 696,000 km)

RTADC Real-Time Automatic Data Correction

RTCM Radio Technical Commission for Maritime Services

RTIM Real Time Ionosphere Monitoring

RTK Real Time Kinematics (DGPS)

RTSW Real-Time Solar Wind data (ACE)

RWC Regional Warning Center

RX Receiver

s (1) number of sunspots ; (2) second

S (1) Sub flare ; (2) NOAA’s scale for Solar radiation storms ; (3) South

S/C Spacecraft

S/N Signal-to-Noise

S4 Scintillation index (amplitude)

SAA South Atlantic Anomaly

SACS Support to Aviation Control Service

SAD Supra-Arcade Downflows

SAFIR Système d'Alerte Foudre par Interférométrie Radioélectrique

SAFIRE SolAr Flux monItoRing Equipment

SAG Sagamore Hill (RSTN, radio observatory)

SAID Subauroral Ion drifts

SAM Solar Aspect Monitor (SDO) - No longer operational

SAMP Simple Application Messaging Protocol

SAMPEX Solar Anomalous and Magnetospheric Particle Explorer (NASA)

SANAE-IV South African National Antarctic Expedition IV (Antarctic research base)

SANSA South African National Space Agency

SAP Science Activity Plan

SAPS Subauroral polarization Streams

SAR (1) Superactive region; (2) Synthetic Aperture Radar ; (3) Stable Auroral Red arcs

SARIF Satellite Risk Prediction and Radiation Forecasts (BAS & UKMO)

SARR Space Absolute Radiometer Reference

SASFF Self-Adjusted Solar Flux Forecasting tool

sat(s) satellite(s)

SATCOM Satellite Communications

SAWS SEP Advanced Warning System

S-band Radio waves with frequencies ranging from 2 to 4 GHz (IEEE)

SBAS Satellite (Space) -based augmentation systems

SBC (1) Secondary Backup-Center (PECASUS) ; (2) Sector Boundary Crossing

SBO Space-Based Observatory

SBUV Solar Backscatter UltraViolet

SC (1) Solar Cycle ; (2) Sudden Commencement

SC24, SC25 Solar Cycle 24, Solar Cycle 25

SCAR Scientific Committee on Antarctic Research

SCATHA Spacecraft Charging AT High Altitudes (P78-2 satellite ; USAF & NASA)

SCD Spacecraft Design (SN-I)

SCIAMACHY SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (ENVISAT)

SCINDA SCIntillation Network Decision Aid (AFRL)

SCIOPS SCIence OPerationS

SCK-CEN Studiecentrum voor Kernenergie - Centre d’Etude de l’Energie Nucléaire

S-class Small class satellite (ESA)

SCNA Sudden Cosmic Noise Absorption

SCO Spacecraft Operation (SN-I)

SCOPE Solar Coronagraph for OPErations

SCORE CME classification via speed (Slow-Common-Occasional-Rare-Extremely rare)

SCOSTEP Scientific Committee on Solar Terrestrial Physics

SDA Sudden Decrease of Atmospherics

SDO Solar Dynamics Observatory

SDU Silicon Detector Units

SDR Software Defined Radio

SEA Sudden Enhancement of Atmospherics

SEB Single-event burnout

SEC Space Environment Center (old name of SWPC)

SECCHI Sun Earth Connection Coronal and Heliospheric Investigation (STEREO)

SED Spectra Energy Distribution

SEE (1) Single Event Effect ; (2) Solar EUV Experiment (TIMED)

SEESAW Space Environment Engineering and Science Applications Workshop

SEII Société Européenne des Ingénieurs et des Industriels

SEISS Space Environment In-Situ Suite (GOES)

SEL Single-event latch-up

SEM (1) Solar EUV Monitor (SOHO) ; (2) Space Environment Monitor (GOES)

SEON Solar Electro-Optical Network (USAF)

SEP Solar Energetic Particle

SEPEM Solar Energetic Particle Environment Modelling (ESA)

SEPVAL SEP model VALidation working meeting

SEPC Space Environment Prediction Center (China)

SES Sudden Enhancements of Signal

SESAR Single European Sky ATM Research

SESC Space Environment Services Center

SEU Single Event Upset (bit flip)

SEVIRI Spinning Enhanced Visible and Infrared Imager

SFA Sudden Field Anomalies

SFD Sudden Frequency Deviations

SFE Solar Flare Effect (“magnetic crochet”)

SFU, sfu Solar Flux Unit (10^-22 W m^-2 Hz^-1)

SGD Solar-Geophysical Data (NOAA)

SGEPSS Society of Geomagnetism and Earth, Planetary and Space Science

SGIArv Archive of Solar and Geomagnetic Indices for drag calculation (SRC PAS)

SGPS Solar and Galactic Proton Sensor (GOES)

SHADOZ Southern Hemisphere Additional Ozonesondes (JOSIE)

SHARP (1) Stratospheric Change and its Role for Climate Prediction (SPARC) ; (2) SHocks: structure, AcceleRation, dissiPation (FMI)

SHF Super High Frequency

SHINE Solar Heliospheric & Interplanetary Environment

SHOCK Solar and Heliospheric Collisionless Kinetics

Si Silicon

SI Sudden Impulse

SI²N SPARC, IOC, IGACO-O3/UV and NDACC

SIC Seismoionospheric Coupling

SID Sudden Ionospheric Disturbance

SIDC Solar Influences Data analysis Center

SIGMA Solar Investigation using a Global coronal Magnetograph

SILSO Sunspot Index and Long-term Solar Observations (ROB)

SIM Spectral Irradiance Monitor (SORCE)

SIMBA Sun-earth IMBAlance radiometer

SIP Solar Information Processing

SIPWork Solar Information Processing Workshop

SIR Stream Interaction Region

SIRTA Site Instrumental de Recherche par Télédétection Atmosphérique (IPSL)

SIS Solar Isotope Spectrometer (ACE)

SISTED Sunlit Ionosphere Sudden TEC Enhancement Detector (UPC)

SITEC Sudden increase of total electron content

SKA Square Kilometre Array

SL Seibersdorf Laboratories

SLOL Signal LOL

SLP Sweeping / Segmented / Single/ Split / Spherical Langmuir Probe

SLT Solar Local Time

SM Spare Model

SMART-L Signaal Multibeam Acquisition Radar for Targeting, L-band

SMD Safety and Metrology Division (Federal Services for Metrology)

SMEI Solar Mass Ejection Imager (Coriolis)

SMILE MWG SMILE - Modeling Working Group

SMILE Solar wind-Magnetosphere-Ionosphere Link Explorer (ESA)

S_min Minimal detectable signal

SMM Solar Maximum Mission (1980-1989)

SMOS Soil Moisture and Ocean Salinity (ESA)

sms short message service

SN-I Space Weather Segment Precursor Services –. Part-1: Definition and Service Consolidation (ESA)

SN, S_n (1) Sunspot Number ; (2) Space weather and Near-earth objects ; (3) Standard normal homogenization tests

SNAP Spring – Negative – Autumn – Positive (CHs)

SNN Space Surveillance Network

SNR Signal-to-Noise Ratio

SO Solar Orbiter

SO5 Solar Orbiter Workshop 5

SOC (1) Science Operations Centre ; (2) Scientific Organizing Committee

SODA (1) SOTERIA Data Archive ; (2) Satellite Orbit DecAy (forecast model ; Uni Graz)

SoDIPE-RTK Software for Determining the Ionospheric Positioning Error on RTK

SODISM SOlar Diameter Imager and Surface Mapper (PICARD)

SoFAST Solar Flare Automated Search Tool

SoHe Meeting of the Italian Community in Solar and Heliospheric Physics

SOHO SOlar & Heliospheric Observatory

SOI Solar Oscillations Investigation (SOHO/MDI ; Stanford)

SOIR Solar Occultation in the Infrared

SOL-ACES SOLar Auto-Calibrating Extreme ultraviolet and ultraviolet Spectrometers (ISS-SOLAR)

SOLAR ESA project onboard ISS (Columbus Laboratory), controlled by B.USOC, and having 3 main instruments: SOVIM, SOLSPEC and SOL-ACES

Solar-C Next Generation Solar physics Mission (JAXA)

SOLERA SOLar Euv flux RAte GNSS proxy (UPC)

SOLAR-ISS Name of the new Solar Reference Spectrum (from 165 to 3000 nm) based on SOLAR/SOLSPEC)

SOLARNET European network of solar physics researchers and facilities (H2020)

SOLAR-v A solar spectral irradiance dataset based on SOLAR/SOLSPEC observations during SC24 (relative variability)

SOLCON SOLar CONstant radiometer

SolEx Solar Explorer (telescope)

SOLID SOLar Irradiance Data exploitation (FP7)

SOLIS Synoptic Optical Long-term Investigations of the Sun (NSO)

SOLMEX SOLar Magnetism EXplorer

SOLMOD Solar Modeling (code)

SolO Solar Orbiter

SoloHI Heliospheric Imagers (SolO)

SOLSPEC SOLar SPECtrometer (ISS-SOLAR)

SOLSTICE Solar Stellar Irradiance Comparison Experiment

SOLVAM SOLar VAriability Monitor

SOLVE Small spacecraft fOr near Lunar enViroment Exploration

SOON Solar Observing Optical Network (USAF/AFWA)

SOOPs Solar Orbiter Operation Plans (SolO)

SOP Standard Operating Procedures

SOPB South Pole Bares (Antarctica, NMDB)

SOPO South Pole (Antarctica, NMDB)

SOP(s) Standard Operating Procedure(s)

SORCE Solar Radiation and Climate Experiment

SoSpIM Solar Spectral Irradiance Monitor (Solar-C)

SOT (1) Space Object Tracking ; (2) Solar Optical Telescope (Hinode)

SOTERIA Solar-Terrestrial Investigations and Archives (EU/FP7)

SOVA SOlar constant and VAriability

SOVAP SOlar VAriability Picard

SOVAR Refurbished SOVA1 radiometer

SOVIM Solar Variations and Irradiance Monitor (ISS-SOLAR)

SOWG Science Operations Working Group

SP Signal Processing

SP4GATEWAY Space Plasma Physics Payload Package conceptual design for the Deep Space Gateway Lunar Orbital Platform

SPA Sudden Phase Anomalies

SPACEMON Space Environment Monitoring workshop

SPADE Small Phased Array DEmonstrator

SPARC (1) Stratosphere-troposphere Processes And their Role in Climate ; (2) Space Applications & Research Consultancy

SPARX Solar Particle Radiation SWx

SPD Solar Physics Division (AAS)

SPDF Solar Physics Data Facility (GSFC)

SPE Solar Proton Event

SPENVIS (-NG) SPace ENVironment Information System (- Next Generation)

SPHINX Solar Particles in the Heliosphere validation INfrastructure for SpWx

SPICE Spectral Imaging of the Coronal Environment (SolO)

SPIE Society of Photo-Optical Instrumentation Engineers

SPM SWIFF Plasmasphere Model

SPoCA Spatial POssibilistic Clustering Algorithm

SPORT Solar Polar ORbit Telescope (China)

SPRING Solar Physics Research Integrated Network Group (SOLARNET)

SPS Science for Peace and Security (NATO)

SPWX Space Weather (military)

Sq Solar quiet (daily variations in the geomagnetic field)

S_RSolar Regular

sr steradian

SRAM Static Random-Access Memory

SRB Solar Radio Burst

SRBE Société Royale Belge des Electriciens

SRC PAS Space Research Center of the Polish Academy of Sciences

SREM Standard Radiation Environment Monitor (Integral, Rosetta)

SRL Space Research Laboratory (UTU)

SSA (1) Space Situational Awareness ; (2) Single Scattering Albedo ; (3) Singular Spectrum Analysis

S-SAIL Solar System Atmospheres’ Investigation and exopLanets

SSB Solar Sector Boundary

SSBC Solar Sector Boundary Crossing

SSC (1) STEREO Science Center; (2) Storm Sudden Commencement

SSCC SSA Space Weather Coordination Centre (ESA)

SSEWG Solar System Exploration Working Group

SSI Solar Spectral Irradiance

SSN (1) SunSpot Number ; (2) Smoothed Sunspot Number

SSN_corr Corrected series of sunspot numbers

SSN_oriOriginal series of sunspot numbers

SSR (1) Solid state recorder; (2) Secondary Surveillance Radar

SST (1) Space Surveillance and Tracking (SN-I) ; (2) Swedish 1-m Solar Telescope

SSWRF II 2^nd international workshop on Small Satellites for Space Weather Research and Forecasting

ST-A, ST-B STEREO-A(head), STEREO-B(ehind) spacecraft

STAFF Solar Timelines viewer for AFFECTS

STCE Solar-Terrestrial Centre of Excellence

STCL Space Technology & Calibration Laboratories

STFC Science and Technology Facilities Council (UK)

STEAM Science, Technology, Engineering, Arts, Mathematics

STEC Slant TEC

STEM Science, Technology, Engineering, Mathematics

STEPPS Solar Terrestrial and Experimental Plasma Physics Synergy

STEREO Solar-TErrestrial RElations Observatory

STET SuperThermal Electron Transport code

STEVE Strong Thermal Emission Velocity Enhancement

STIX Spectrometer Telescope for Imaging X-rays (SolO)

STM Structural Model

STORM Solar system plasma Turbulence: Observations, inteRmittency and Multifractals

STSM Short-Term Scientific Mission (COST)

SUMER Solar Ultraviolet Measurements of Emitted Radiation (SOHO)

SunPy software library for solar physics based on Python

SunSCC Automated tool for sunspot segmentation, clustering, and classification (ROB)

SuperDARN Super Dual Auroral Radar Network

SURFEX Surface Externalisée (surface model developed by Météo France)

SUVI Solar Ultraviolet Imager (GOES16-…)

Sv Sievert (J/kg ; dose equivalent radiation: equivalent biological effect of the deposit of a joule of radiation energy in a kilogram of human tissue)

SVI San Vito (RSTN, radio observatory)

SVO Solar Virtual Observatory

SVW Sun Visibility Window

SW (1) Space weather ; (2) Solar wind ; (3) Space Weather (journal)

SWEAP Solar Wind Electrons Alphas and Protons (PSP)

SW4E Space Weather for Engineers

SWA Solar Wind Analyser (SolO)

SWACI Space Weather Application Center – Ionosphere (DLR)

SWAMIS Southwest Automatic Magnetic Identification Suite

SWAN Solar Wind Anisotropies (SOHO)

SWANS Space Weather and Navigation Systems

SWAP Sun Watcher using APS detector and image Processing (PROBA2)

SWARM Three identical satellites measuring Earth’s MF (ESA)

SWAVES STEREO/WAVES instrument (STEREO)

SWE Space WEather

SWEC Space Weather Education Centre (STCE)

SWEK Space Weather Event Knowledgebase

SWENET (European) Space WEather NETwork

SWEPAM Solar Wind Electron, Proton, and Alpha Monitor (ACE)

SWF ShortWave Fade

SWFC Space Weather Forecast Center

SWG Science Working Group

SWHV Space weather helioviewer (jHV)

SWIC Space Weather Introductory Course

SWIFF Space Weather Integrated Forecasting Framework

SWiFT Solar Wind Flux Tube (forecast model)

SWMF Space Weather Modeling Framework

SWOC Space Weather Operations Centre

SWOP Space Weather OPerations group (SIDC)

SWPC Space Weather Prediction Center (USA)

SWRC Space Weather Research Center

SwRI Southwest Research Institute

SWS Space Weather Services (Australia)

SWSC Space Weather and Space Climate journal (old acronym)

SWT Science Working Team

SWWT (European) Space Weather Working Team

SWx Space weather

SXI Solar X-ray Imager (GOES12-15)

SXR Soft x-rays

SXT Soft X-Ray Telescope (Yohkoh)

SYM-H A geomagnetic index (nT) similar to the Dst index, but with 1-min time resolution and different stations, to describe the symmetric (SYM) disturbances of the horizontal (H) component of the geomagnetic field

SZA Solar Zenith Angle

T (1) Tesla (1 Tesla = 10.000 Gauss) (2) Temperature ; (3) Tenflare (SRB) ; (4) Terabyte (10¹² bytes)

t Time

TACSAT Tactical Satellite Communications

TaD Topside sounder model profiler – assisted Digisonde

TAI Temps Atomique International

TAP Table Access Protocol

TAS Technology Applications and Science

TB Terabyte (10¹² bytes)

TCS Thematic Core Services

TEC Total Electron Content

TEC-EES Space Environments and Effects section (ESA/ESTEC)

TAP Table Access Protocol

Tech-TIDE Warning and Mitigation Technologies for TIDs Effects

TECO TEchnical Conference on meteorological and environmental instruments and methods of Observation (WMO)

TECu TEC unit (10¹⁶e^-m^-2)

TEPA Thunderstorms and Elementary Particle Acceleration

TESS Triennial Earth-Sun Summit

T-FORS Travelling ionospheric disturbances FORecasting System

tg Propagation time

TGO (1) Trace Gas Orbiter (Exomars) ; (2) Tromsø Geophysical Observatory

TGSE Thermic Ground Support Equipment

THEMIS (1) Time History of Events and Macroscale Interactions during Substorms (NASA mission) ; (2) Télescope Héliographique pour l’Étude du Magnétisme et des Instabilités Solaires (solar telescope CNRS)

THESOW Turbulence and Heating in the Solar Wind

THOR Turbulence Heating ObserveR

THz Terahertz (10¹²/s)

TID (1) Travelling Ionospheric Disturbance (2) Total Ionizing Dose

TIM Total Irradiance Monitor

TIMED Thermosphere Ionosphere Mesosphere Energetics and Dynamics (NASA satellite)

TiN Titanium nitride

TIO Trans-IOnospheric link (SN-I)

TIR Thermal InfraRed

TL Tube Luminescent

TLE Transient Luminous Event

TMPU Thermal Plasma Measurement Unit (PROBA2)

TMR Triple-modular redundancy

TN True Negative

TOA Top Of Atmosphere

TOAR Tropospheric Ozone Assessment Report

TOAR-II Tropospheric Ozone Assessment Report, Phase II

TOPERS Planets: Tracing the Transfer, Origin, Preservation, and Evolution of their ReservoirS

TOPROF Towards Operational ground based PROFiling with ceilometers, doppler lidars and microwave radiometers for improving weather forecasts

TOR Transmitters-of-Opportunity Reception

TOSCA Towards a more complete assessment of the impact of solar variability on the Earth’s climate

TP True Positive

TRACE Transition Region and Coronal Explorer (1998-2010)

TRACTEBEL International company for consultancy and engineering; merger from Tractionel and Electrobel

TREASURE Training Research and Applications Network to Support the ultimate real-time high-accuracy EGNSS solution

TREx Transition Region Explorer (Canada)

TRF (1) TIM Radiometer Facility ; (2) TSI Radiometer Facility

TRL Technology Readiness Level

TROPOMI TROPOspheric Monitoring Instrument (Sentinel-5 Precursor)

TSI Total Solar Irradiance

TVAC Thermal-VACuum chamber

Tx , TX Transmitter

UAH Universidad de Alcalá / University of Alcala (Spain)

UAV Unmanned Aerial Vehicle

UCAR University Corporation for Atmospheric Research

UCD Unified content descriptors

UCL, UCLouvain Université Catholique de Louvain

UFO (1) Unidentified Flying Object ; (2) University FOrum (Ghent, Belgium)

UHF Ultra High Frequency (300 MHz - 3 GHz)

UiT University of Tromsf ; Arctic University of Norway

UK United Kingdom

UKMO UK Met Office

UKRI UK research and Innovation

UKUS UK-Ukraine-Spain

ULB Université Libre de Bruxelles

ULF Ultra-Low Frequency (0.3-3 kHz)

ULg Université de Liège

Ulysses A joint ESA/NASA/Canada NRL mission to study the Sun (1990-2009; no acronym)

UMASEP University of Málaga Solar particle Event Predictor

UNCOPUOS United Nations Committee on the Peaceful Use of Outer Space

Uni Graz University of Graz

UNITER Sciences de l'univers, de l'espace, de la terre et du climat

UNOOSA United Nations Office for Outer Space Affairs

UOA University Of Athens

UPC Universitat Politècnica de Catalunya / Technical University of Catalonia (Spain)

URAN Ukrainian Radio Interferometer of NASU

URL Uniform Resource Locator

URSI International Union of Radio Science - Union Radio-Scientifique Internationale

US(A) United States (of America)

USAF United States Air Force

USAFWA US AFWA

usb, USB Universal Serial Bus

USET Uccle Solar Equatorial Table (ROB/SIDC)

USGS US Geological Survey

USU Utah State University

UT(C) (Coordinated) Universal Time

UTL Upper ion Transition Level

UTLS Upper Troposphere-Lower Stratosphere

UTR Ukrainian T-shaped Radio telescope

UTU University of Turku (Finland)

UV Ultraviolet

UVC-II Second solar ultraviolet radiometer comparison campaign

UVCS UV Coronagraph Spectrometer (SOHO)

UVIS Ultraviolet and Visible

UVRIR UV and Red IR detector(MSU)

UVSP UV Spectrometer/Polarimeter (SMM)

v Velocity (speed)

V Volt

V1, 2, … Version 1, 2, …

VACNT Vertically Aligned Carbon Nanotubes

VAP Van Allen Probe (-A and -B)

VarSITI Variability of the Sun and Its Terrestrial Impact

VBI Visible Broadband Imager (DKIST)

VenSpec-H Venus Spectrometer with High resolution (EnVision ; ESA)

VERSIM VLF/ELF Remote Sensing of Ionospheres and Magnetospheres

VESPA Virtual European Solar and Planetary Access

VEX Venus Express (2005-2015)

VHDL VHSIC Hardware Description Language

VHF Very High frequency (30-300 MHz)

VHSIC Very High Speed Integrated Circuit

VI Vertical Incidence

VIP Very Important Person

VIRGO Variability of solar IRradiance and Gravity Oscillations (SOHO)

VIS (1) Visible ; (2) Visual

VISION Visible Spectral Imager for Occultation and Nightglow

VITO Flemish institute for technological research

VKI Von Karman Institute

VLA Very Large Array (USA)

VLF Very Low Frequency (3-30 kHz)

VO Virtual Observatory

VOEvent Virtual Observatory Event

Vol. Volume

Vp Plasma Potential

VPL Vertical Protection Level

VSC (1) Vliebergh-SencieCentrum (Belgium) ; (2) Volontaire Service Civique (voluntary personnel for civil services)

VSOC Venus Express Science Operations Centre

VSWMC Virtual Space Weather Modelling Centre

VSx Virtual Spacecraft

VTEC Vertical TEC

VTI Ieperse school voor Wetenschap en techniek

VTT Technical research Centre of Finland

VUB Vrije Universiteit Brussel

VUV Vacuum Ultraviolet

VVS Vereniging Voor Sterrenkunde (Belgian Astronomical Association

W (1) Watt; (2) West

W/m² Watt per square meter

WAAS Wide Area Augmentation System (GPS/North-America ; USA)

WALCORS WALlonia Continuous OpeRating System

WAMS Wide Area Monitoring System

WAVACS WAter VApor in the Climate System

WAVES Radio and plasma wave investigation (WIND, STEREO)

WBGM Wide Band Gap Material

WDC World Data Center

WDS World Data Service

WFOV Wide Field Of View

WG Working Group

WGCV Working Group on Calibration and Validation

WGN WerkGroepnieuws (Working Group News, bimonthly journal of the IMO)

WHISPER Waves of High Frequency and Sounder for Probing of Density by Relaxation (Cluster)

WHPI Whole Heliosphere and Planetary Interactions

WISA Waves and Instabilities in the Solar Atmosphere

WISPR Wide-field Imager for Solar Probe (PSP)

W_L Energy of a Longmuir wave

WL White light

WLF White-light flare

WMFR Weighted mean flare rate

WMO World Meteorological Organization

WP Work Package

WPGM Western Pacific Geophysics Meeting

WPI Wave-Particle Interactions

WRC World Radiation Center

WRF-Chem Weather Research and Forecasting model coupled with Chemistry

WRR World Radiometric Reference

WS Workshop

WSA (1) Wang-Sheeley-Arge (model for solar wind) ; (2) Weddell Sea Anomaly

WTD waiting-time distribution

X-band Radio frequency band from 8-12 GHz

X-class flare Extreme x-ray flare

XML Extensible Markup Language

XRS X-ray sensor (GOES)

XRT X-Ray Telescope (Hinode)

XUV Extreme Ultraviolet

Yohkoh An ISAS (Japan) solar mission: Solar-1 satellite (“sunbeam”) (1991-2001)

yr year

Z Proton number

Zpc McIntosh sunspot classification: ‘Z’ is the modified Zurich class, ‘p’ describes the penumbra of the principal spot, and ‘c’ describes the distribution of spots in the group’s interior

Zr Zirconium

ZTD Zenith tropospheric Total Delay

Other

~ (1) About (2) proportional to

⫽ Parallel

°C degrees Celsius

°C dec^-1 °C per decade

% Percentage

% dec^-1 change (percentage) per decade

⏊ Perpendicular

1D, 2D, 3D,... One, two, three,... dimensional

³He Stable isotope of Helium

3DEES 3D Energetic Electron Spectrometer (Proba-3)

4CESM Chapman Conference on Causes and Consequences of the Extended Solar Minimum between SC23 and SC24

4S Small Satellites Systems and Services

6U 6 Units (cubesats)

α Power-law slope

α-particle Helium nucleus

β Plasma beta parameter (the ratio of the plasma pressure to the magnetic pressure)

Δ Delta (difference)

δ Delta (difference)

λ wavelength

λ_e electron inertial length

μ Magnetic moment of a gyrating particle

μBOS micro Bolometric Oscillation Sensor

μm micrometer (10^-6 meter)

μ-waves microwaves (300 MHz - 300 GHz)

ν Frequency

W_ce , W_cp electron-cyclotron frequencies, proton-cyclotron frequencies

ρ_i ion gyroradius

ρ_r gyroradius

σ (1) sigma (confidence level) ; (2) Radar cross section

σ_φ Scintillation index (phase)

Φ Flux

φ Phi angle

τ (1) Ionospheric slab thickness (meters) ; (2) Time

τ , t Time

Submitted by JJ on Mon, 2021/07/05 - 11:01

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