SWx acronyms

Original: 14 July 2021

Welcome to the STCE's space weather (SWx) acronym webpage! This non-exhaustive list of nearly 1500 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                           (1) Area ; (2) Article ; (3) Ampère ; (4): Mount Wilson : a magnetically unipolar sunspot group (alpha)

Å                           Ångström (0.1 nm or 10-10 m)

A/C                      Aircraft

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

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)

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

ACM                     Asteroids, Comets and Meteors conference

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

ACVE                   Atmospheric Composition Validation and Evolution

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

Ae                          Effective Area

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

AGN                     Active Geodetic Network

AGU                      American Geophysical Union

AGW                    Acoustic Gravity Waves (drivers of TID)

AH-64                  Apache military helicopter

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

ak, Ak                    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

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                    Air Operations Control Station

AOD                     Aerosol Optical Depth

AOGS                    Asia Oceania Geosciences Society

AOSWA               Asia-Oceania Space Weather Alliance

ap, Ap                    Resp. a 3-hour and daily geomagnetic index, ranging from 0 (quiet) to 400 nT (extremely severe storm)

ApJ                       The Astrophysical Journal

APOD                   Astronomy Picture of the Day (NASA)

AP-RASC             Asia-Pacific Radio Science Conference

APS                      (1) Active Pixel Sensor ; (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                        Active Region

Ar                         Argon

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

ASCA                    Advanced Satellite for Cosmology and Astrophysics (ka 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

Asl, ASL               above sea level

ASOPOS               Assessment of Standard Operating Procedures for OzoneSondes

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

ASTRA                 Atmospheric & Space Technology Research Associates

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

ATC                      Air Traffic Control

ATLAS                 Atmospheric Laboratory for Applications & Science

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

ATMOS                Advances in Atmospheric Science and Applications

AT-RASC             Atlantic Radio Science meeting

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

AVL                      ASIMUT-(V)LIDORT model (IASI)

AWACS                Airborne early Warning And Control Station

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.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

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

BER                      Backscatter-to-Extinction Ratio

BESSY                  Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung

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)

BGS                       British Geological Survey

BIPM                    Bureau International des Poids et Mesures

BIRA                    Koninklijk Belgisch Instituut voor Ruimte-Aëronomie

BISA                     Royal Belgian Institute for Space Aeronomy

BKG                      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

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

BRAMS                Belgian RAdio Meteor Stations

BSI                        Back-Side Illuminated

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)

c0                          Speed of light in vacuum

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                   Copernicus Atmosphere Monitoring Service

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

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

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

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)

CIR                       Co-rotating Interaction Region

CIS                        Cluster Ion Spectrometry (Cluster)

CISM                    Center for Integrated Space Weather Modeling

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

CLW                     Coronal Loops Workshop

cm                        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

CNES                    Centre national d'études spatiales (France)

CNRS                   Centre national de la recherche scientifique (France)

CNSS                    COMPASS Navigation Satellite System

CO2                       Carbon Dioxide

Co60                    Cobalt 60

CODE                   Center for Orbit Determination

CODE                   Center for Orbit Determination in Europe

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

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

CP                         Coronagraph/Polarimeter (SMM)

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

CR                        Carrington Rotation

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)

CRCM                  Comprehensive Ring Current Model (NASA/GSFC)

CRF                      Cosmic Ray Flux

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

CW                       Continuous Wave



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

DAU                     Data Acquisition Unit

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

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

DGPS                    Differential Global Positioning System

DH                        Decametric-Hectometric

DIARAD              DIfferential Absolute RADiometer

DIAS                     Digital Upper Atmosphere Server

DIDBase              Digital Ionosonde network DataBase

Digisonde            Digitally Integrating Goniometric IonoSONDE

DIGISUN              A software application for digitization of scanned sunspot drawings

DIono                     Ionospheric delay

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

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

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

DOP                      Dilution Of Precision

DOT                      Dutch Open Telescope (45cm aperture)

DoY, DOY            Day of Year

DPD                      Debrecen Photographic Data

DPM                     Data Processing Model

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)

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

DTropo                   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)



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

e-                           electron

E1, E5a                Galileo frequencies: E1 = 1575.42 MHz , L2 = 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

EDP                      Electron Density Profile

Eds.                      Editors

EEJ                       Equatorial ElectroJet current

EESC                    Equivalent Effective Stratospheric Chlorine

EFR                      Emerging Flux Region

EGNOS                 European Geostationary Navigation Overlay Service

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                      Extreme High Frequency

EIA                       Equatorial Ionization Anomaly

EIG                       Economic Interest Grouping

EIS                        Extreme-Ultraviolet Imaging Spectrometer (Hinode)

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)

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                      EUREF Permanent Network

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                    ERA-Interim

ERB(S)                Earth Radiation Budget (Satellite)

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               European SpaceCraft for the study of Atmospheric Particle Escape

ESD                      Electrostatic Discharge

ESERO                 European Space Education Resource Office

ESF                       Equatorial Spread F

ESIO                     EUV Solar Imager for Operations

ESLAB                  European Space Research Organisation 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)

ESPM                   European Solar Physics Meeting

ESRIN                  European Space Research Institute

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

ESTEC                  European Space Research and Technology Centre

ESWC                   European Space Weather Community

ESWP                   European Space Weather Portal

ESWW                 European Space Weather Week

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

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)

eV                         electronvolt (1.6 . 10-19 Joule)

EVA                      Extravehicular activity

EVE                      Extreme ultraviolet Variability Experiment (SDO)

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

F10.7 cm                  Solar radio flux at 10.7 cm wavelength

F10.7P                 Proxy for F10.7 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

FAM                     First Attendees Meeting

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

FeIX                     8 times ionized iron

FFT                       Feature Finding Team

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

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

foF1                      Critical frequency F1-layer

foF2                      Critical frequency F2-layer

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)

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

FST                       Facility Science Team (ISS-SOLAR)

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

FTS                       Fourier Transform Spectrometer

FU                         Frederick University

FUV                      Far Ultraviolet

FWC                     Full Well Capacity

FY3E                    FengYun: 5th satellite in the 3rd 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)

g                            number of sunspot groups

G4SUW                Geant4 Space Users Workshop

GAGAN                GPS Aided GEO Augmented Navigation (India)

Galileo                 European GNSS

GAMIT                 GPS Analysis at MIT

GaN                      Gallium nitride

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 (at altitude of 35.786 kilometers)

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

Gfg2                                             GNSS 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)

GmbH                  Gesellschaft mit beschränkter Haftung (Company with limited liability)

GMC                     Geostationary Magnetopause Crossing

GMDSS                 Global Maritime Distress and Safety System

GMS                     Geomagnetic Storm

GNSS                    Global Navigation Satellite System

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)


GONG                   Global Oscillation Network Group

GOP                      Geodetic Observatory Pecný

GP-B                     Gravity Probe B (2004-2010)

GPS                       Global Positioning System (USA)

GRAPE                 GNSS Research and Application for Polar Environment

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

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

HaSTeNet            H-alpha Solar flare patrol TElescopic NETwork

hc                          Critical height

H-component    Horizontal component of the MF

HCS                      Heliospheric Current Sheet

He                         Helium

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

HEK                     Heliophysics Events Knowledgebase

HELCATS            HELiospheric Cataloguing, Analysis and Techniques Service

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)

HI                         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)

hmF2                     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

HPL                      Horizontal Protection Level (FAA)

HPS                      Heliospheric Plasma Sheet

HQ                        Headquarters

hr                          hour

HRI                      High-Resolution Imager (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

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                            Intensity

i                            ion(s)

i.e.                        “id est” (that is)

I/Ps                      Ionosphere-Plasmasphere system

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

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

IAU                       International Astronomical Union

IAUS                     IAU Symposium

IAW                     Inertial Alfvén Waves

IBUKS                  India, Belgium, UK, and Spain

ICAC                    International Conference on Aerosol Cycle

ICAO                    International Civil Aviation Organization

ICEAA                  International Conference on Electromagnetics in Advanced Applications

IceCON                Constraining Ice Mass Change in Antarctica

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

ICRC                    International Cosmic Ray Conference

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

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

IGS                        International GNSS Service

IGSO                     Inclined geosynchronous orbit

IGY                       International Geophysical Year (1957-1958)

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

INAF                    Istituto Nazionale di Astrofisica (Italy)

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

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

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)

IR                         Infrared

IRACON              Inclusive Radio Communication Networks for 5G and beyond

IRAP                    Institut de Recherche en Astrophysique et Planetologie (France)

IRENE                 International Radiation Environment near Earth

IRI                        International Reference Ionosphere

IRIS                      Interface Region Imaging Spectrograph (NASA)

IRM                      Institut Royal Météorologique

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

Irr.                        (1) Irradiance ; (2) Irregular

IRSN                    Institut de Radioprotection et de Sûreté Nucléaire

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))

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                     International Symposium on Tropospheric Profiling

ISU                       International Space University

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

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 Vapor



J                            Joule

JAXA                    Japan Aerospace eXploration Agency

JBP                       Jet Bright Point

JGR                       Journal of Geophysical Research

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

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*                         Local 1-minute resolution K index

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

KAW                    Kinetic Alfvén Waves

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)

km                        kilometer

km/s                    kilometers per second

KMI                      Koninklijk Meteorologisch Instituut

KNMI                   Koninklijk Nederlands Meteorologisch Instituut

KNVWS               Koninklijke Nederlandse Vereniging voor Weer- en Sterrenkunde

Kp                         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)

Ks                          Standardized K index

KSB                      Koninklijke Sterrenwacht van België

KSC                      Kagoshima Space Center (Japan)

KSO                      Kanzelhöhe Observatory for Solar and Environmental Research (Austria)

KSP                      Key Science Project

KU                        K unit (geomagnetic)

KUL                      Katholieke Universiteit Leuven

kV                         kiloVolt (103 Volt)



L                           (1) Letter (manuscript); (2) Length; (3) Loss

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)

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)

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

LOUI-Base          Lowell ObliqUe Incidence database

LPV                      Localizer performance with vertical guidance (WAAS)

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*)

LT                         Local Time

LUCE                    LUnar CubeSats for Exploration

LUF                      Lowest Useable Frequency

LVF                       Linear Variable Filter

LVNL                    Luchtverkeersleiding Nederland

LW                       Langmuir Wave

LWS                     Living With a Star

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



m3                         Cubic meter

M3G                      Metadata Management and distribution system for Multiple GNSS Networks

MAARBLE           Monitoring, Analyzing and Assessing Radiation Belt Loss and Energization

MADAWG           Modelling and Data analysis Working Group (SolO)

MAG                     Magnetometer instrument (ACE, DSCOVR, SolO)

MAGION-5          A Czech subsatellite

MAJIS                   Moons And Jupiter Imaging Spectrometer (JUICE)

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)

MB                        Megabyte (106 bytes)

mbar                    millibar

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

M-class flare       Medium x-ray flare

M-class                Medium class satellite (ESA)

MCM                    Management Committee Meeting

MDI                      Michelson Doppler Imager (SOHO)

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         Meteorological satellite

METIS                  Multi Element Telescope for Imaging and Spectroscopy (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)

MIT                      Massachusetts Institute of Technology

MJD                      Modified Julian Day

MK                       Million degrees Kelvin

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

MLE                     Maximum Likelihood Estimate

MLH                     Mixing Layer Height

ML-Helio             Machine Learning in Heliophysics

MLSO                   Mauna Loa Solar Observatory (USA)

MLT                     Magnetic Local Time

mm                       millimeter (10-3 meter)

MMS                     Magnetospheric MultiScale mission (NASA ; 4 spacecraft)

mm/s                   millimeter per second

MOF                     Magneto-optical filter

MoMo                  Model of Mars Ionosphere

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

MPS                      Max Planck Institute for Solar System Research

MPS-LO               Magnetospheric Particle Sensor – LOw 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

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                     Maximum Useable Frequency

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

nA                        nano-Ampère (10-9 Ampère)

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

NASA                   National Aeronautics and Space Administration

NASU                   National Academy of Sciences of Ukraine

NatGeo                National Geographic

NATO                   North Atlantic Treaty Organization

NAVIC                 NAVigation with Indian Constellation (Regional; Indian GNSS)

NCAR                   National Center for Atmospheric Research

NCEI                    National Centers for Environmental Information

NDACC                Network for the Detection of Atmospheric Composition Change

Ne                         (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)

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

NmF2                     peak electron density of F2-layer

NO, NO+               Nitric oxide, ionized NO

No.                       Number of

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)

NOx                       Refers to NO and NO2

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

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

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

NVBM                  Nederlandse Vereniging ter Bevordering van de Meteorologie

NWP                    Numerical Weather Prediction



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

O3                         Ozone

O3S-DQA             Ozonesonde - Data Quality Assessment

OBEE                   Outer belt electron enhancements

OD                        Onderdepartement

ODC                      On Duty Center (PECASUS)

ODS                      Ozone Depleting Substances

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)



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

PARAFOG           Predictive Alert of RAdiation FOG

PATH                   Particle Acceleration and Transport in the Heliosphere model

PB                         Petabyte (1015 bytes)

PBC                      Primary Backup-Center (PECASUS)

PbS                       Lead Sulfide

PC                         Polar Cap; a dimensionless geomagnetic index based on a single nearpole station (one for each pole)

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

PCO                      Phase Center Offset

PCTR                   Prominence-Corona Transition Region

PCV                      Phase Center Variation

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)

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

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)

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               Fast warning message for important SWx events issued by a RWC (no acronym)

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 for the Development of scientific Experiments

ps                          picosecond (10-12 second)

PSF                       Point Spread Function            

PSR                      Primary Surveillance Radar

Pt                          Transmitted power

PTB                      Physikalish-Technische Bundesanstalt (Germany)

PTC                      Photon Transfer Curve

PWOM                 Polar Wind Outflow Model



q                           Charge

Q                           Quantity (e.g. e-, H2O,...)

Q&A                     Questions and Answers

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

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

RAAF                   Royal Australian Air Force

RAC                      Radar Auroral Clutter

RACA                   Rencontre Astronomique Centre Ardenne

RADAR                RAdio Detection And Ranging

RADECS              RADiation Effects on Components and Systems

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

RAE                      Royal Academy of Engineering (UK)

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

RBR                      Radio burst (fixed frequency)

RC                        Ring Current

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

RE                         Earth radius (6378 km)

R-ESC                  Space Radiation ESC

ReSourCE            Radio Sciences Research on AntarCtic AtmosphEre

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)

RO                        Radio Occultation

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)

Rsun                       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

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

SARR                   Space Absolute Radiometer Reference

SASFF                  Self-Adjusted Solar Flux Forecasting tool

sat(s)                   satellite(s)

SATCOM              Satellite Communications

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)

SEII                      Société Européenne des Ingénieurs et des Industriels

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)

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)

SHADOZ              Southern Hemisphere Additional Ozonesondes (JOSIE)

SHARP                 Stratospheric Change and its Role for Climate Prediction (SPARC)

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

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)

SITEC                   Sudden increase of total electron content

SKA                      Square Kilometre Array

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

SMEI                    Solar Mass Ejection Imager (Coriolis)

Smin                      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, Sn                   (1) Sunspot Number ; (2) Space weather and Near-earth objects

SNAP                   Spring – Negative – Autumn – Positve (CHs)

SNN                      Space Surveillance Network

SNR                      Signal-to-Noise Ratio

SO5                       Solar Orbiter Workshop 5

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

SODA                   SOTERIA Data Archive

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)

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-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)

SOLCON              SOLar CONstant radiometer

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 SPECtral irradiance measurements (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

SOPs                     Standard Operating Procedures

SORCE                 Solar Radiation and Climate Experiment

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

SPA                      Sudden Phase Anomalies

SPADE                 Small Phased Array DEmonstrator

SPARC                 Stratosphere-troposphere Processes And their Role in Climate

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)

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)

SR                               Solar Regular

sr                           steradian

SRAM                   Static Random-Access Memory

SRB                      Solar Radio Burst

SRBE                    Société Royale Belge des Electriciens

SRC                      Space Research Center of the Polish Academy of Sciences

SREM                   Standard Radiation Environment Monitor (Integral, Rosetta)

SSA                       (1) Space Situational Awareness ; (2) Single Scattering Albedo

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

SSEWG                 Solar System Exploration Working Group

SSI                        Solar Spectral Irradiance

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

SSNcorr                 Corrected series of sunspot numbers

SSNori                                      Original 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

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

STEC                    Slant TEC

STEPPS                Solar Terrestrial and Experimental Plasma Physics Synergy

STEREO               Solar-TErrestrial RElations Observatory

STET                    SuperThermal Electron Transport code

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

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)

SVW                     Sun Visibility Window

SW                        (1) Space weather ; (2) Solar wind

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 Center (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

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

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

SZA                       Solar Zenith Angle



T                           (1) Tesla (1 Tesla = 10.000 Gauss) (2) Temperature ; (3) Tenflare (SRB)

t                            Time

TACSAT               Tactical Satellite Communications

TaD                      Topside sounder model profiler – assisted Digisonde

TAI                       Temps Atomique International

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)

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

tg                          Propagation time

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

TGSE                    Thermic Ground Support Equipment

THEMIS               Time History of Events and Macroscale Interactions during Substorms (NASA mission)

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)

TL                         Tube Luminescent

TLE                      Transient Luminous Event

TMPU                  Thermal Plasma Measurement Unit (PROBA2)

TMR                     Triple-modular redundancy

TN                        True Negative

TOA                      Top Of Atmosphere

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

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

TRL                      Technology Readiness Level

TSI                        Total Solar Irradiance

TX                         Transmitter



UAV                      Unmanned Aerial Vehicle

UCL                      Université Catholique de Louvain

UFO                      Unidentified Flying Object

UHF                      Ultra High Frequency (300 MHz - 3 GHz)

UiT                       University of Tromsf ; Arctic University of Norway

UK                        United Kingdom

UKUS                   UK-Ukraine-Spain

ULB                      Université Libre de Bruxelles

ULF                      Ultra-Low Frequency (0.3-3 kHz)

ULg                       Université de Liège

UNCOPUOS         United Nations Committee on the Peaceful Use of Outer Space

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

URAN                  Ukrainian Radio Interferometer of NASU

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

US(A)                   United States (of America)

USAF                    United States Air Force

USAFWA             US AFWA

USET                    Uccle Solar Equatorial Table

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

UV                        Ultraviolet

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, …

VAP                      Van Allen Probe (-A and -B)

VarSITI                Variability of the Sun and Its Terrestrial Impact

VBI                       Visible Broadband Imager (DKIST)

VERSIM               VLF/ELF Remote Sensing of Ionospheres and Magnetospheres

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)

Vp                         Plasma Potential

VPL                      Vertical Protection Level

VSC                       Vliebergh-SencieCentrum

VSOC                    Venus Express Science Operations Centre

VSWMC               Virtual Space Weather Modelling Centre

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



W                          (1) Watt; (2) West

W/m2                   Watt per square meter

WAAS                  Wide Area Augmentation System (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

WG                       Working Group

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

WL                        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

WRC                    World Radiation Center

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

Zr                          Zirconium

ZTD                      Zenith tropospheric Total Delay



~                           (1) About (2) proportional to

⫽                           Parallel

°C                          degrees Celsius

⏊                          Perpendicular

1D                         One dimensional

2D                         Two dimensional

3D                         Three dimensional

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

4D                         Four dimensional

4S                         Small Satellites Systems and Services

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

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

ρi                          ion gyroradius

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

σφ                        Scintillation index (phase)

Φ                          Flux

φ                           Phi angle

τ                            Ionospheric slab thickness (meters)



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