| ABC | Atmospheric Brown Cloud |
| ACCENT | Atmospheric Composition Change European Network of Excellence |
| ACE | Atmospheric Chemistry Experiment |
| AGAGE | Advanced Global Atmospheric Gases Experiment |
| AGGI | Annual Greenhouse Gas Index |
| AGU | American Geophysical Union |
| AIRS | Advanced InfraRed Sounder (instrument on NASA’s Aqua satellite) |
| AMAP | Arctic Monitoring and Assessment Programme |
| AMDAR | Aircraft Meteorological Data Relay Programme |
| AMIS | Air Management Information System |
| AOD | Aerosol Optical Depth |
| AREP | Atmospheric Research and Environment Programme |
| ASEAN | Association of South-East Asian Nations |
| ASRC-SUNY | Atmospheric Sciences Research Centre, State University of New York (SUNY), Albany NY, USA |
| ATMOS | Atmospheric Trace Molecule Spectroscopy |
| BAPMoN | Background Air Pollution Monitoring Network |
| BIPM | Bureau of International Weights and Measures |
| BoM | Bureau of Meteorology, Melbourne, Australia |
| BSRN | Baseline Surface Radiation Network |
| CACGP | Commission for Atmospheric Chemistry and Global Pollution |
| CAPMoN | Canadian Air and Precipitation Monitoring Network |
| CARIBIC | Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container |
| CAS | Commission for Atmospheric Sciences |
| CAS WG | CAS Working Group on Environmental Pollution and Atmospheric Chemistry (replaced by the JSC OPAG-EPAC) |
| CBS | Commission for Basic Systems |
| CCalL | Central Calibration Laboratory |
| CCL | Central Calibration Laboratory, in most cases host of the designated WMO standard for a particular variable |
| CCN | Cloud Condensation Nuclei |
| CEOPs | Coordinated Enhanced Observing Periods |
| CEOS | Committee on Earth Observation Satellites |
| CFCs | Chlorofluorocarbons |
| CG | Congress |
| CGMS | Coordination Group for Meteorological Satellites |
| CIMO | Commission for Instruments and Methods of Observation |
| CIPM | Committee for International Weights and Measures |
| CLAES | Cryogenic Limb Array Etalon Spectrometer |
| CLIVAR | Climate Variability and Predictability |
| CLRTAP | Convention on Long-Range Transboundary Air Pollution |
| CMAR | CSIRO Marine and Atmospheric Research |
| CMDL | Climate Monitoring and Diagnostic Laboratory, NOAA (now Global Monitoring Division of the Earth System Research Laboratory, NOAA ESRL) |
| COST | European Cooperation in the field of Scientific and Technical Research |
| COST715 | Urban meteorology applied to air pollution problems |
| CRISTA | CRyogenic Infrared Spectrometers and Telescopes for the Atmosphere |
| CSIRO | Commonwealth Scientific and Industrial Research Organisation |
| DA | Data Assimilation |
| DEBITS | Deposition of Biogeochemically Important Trace Species |
| DLR | German Aerospace Centre, Oberpfaffenhofen, Wessling, Germany |
| DOAS | Differential Optical Absorption Spectroscopy |
| DOAS/SAOZ | Differential Optical Absorption Spectroscopy/Système d’Analyse par Observations Zénithales |
| DQO | Data Quality Objective |
| EANET | Acid Deposition Monitoring Network in East Asia |
| EARLINET | European Aerosol Research Lidar Network to Establish an Aerosol Climatology |
| EC | Executive Council of WMO |
| EC | European Commission |
| ECC | Electro Chemical Sonde |
| ECD | Electron Capture Detection |
| ECMWF | European Centre of Medium Range Weather Forecast |
| ECVs | Essential Climate Variables |
| EEA | European Environment Agency |
| EGU | European Geosciences Union |
| EMEP | Cooperative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe |
| EML | Environmental Measurements Laboratory, New York, USA |
| Empa | Swiss Federal Laboratories for Materials Testing and Research, Dübendorf, Switzerland |
| ENV | Environment Division of the Secretariat of the World Meteorological Organization |
| EPAC | Environmental Pollution and Atmospheric Chemistry |
| ERI | European Research Infrastructure |
| ESA | European Space Agency |
| ESRL | Earth System Research Laboratory, NOAA |
| ETEX | European Tracer Experiment |
| ET-NRT CDT | Expert Team on Near-real-time Chemical Data Transfer |
| ET-WDC | Expert Team World Data Centre |
| EU | European Union |
| EUROHYDROS | European Network for Atmospheric Hydrogen observations and studies |
| EUROTRAC | European Experiment on Transport and Transformation of Environmentally Relevant Trace Constituents in the Troposphere over Europe |
| EUSAAR | European Supersites for Atmospheric Aerosol Research |
| EUVDB | European UV Data Base |
| FLUXNET | International network measuring terrestrial carbon, water and energy fluxes |
| FMI | Finnish Meteorological Institute |
| FTIR | Fourier Transform Infrared (Spectroscopy) |
| FUMAPEX | Integrated Systems for Forecasting Urban Meteorology, Air Pollution and Population Exposure |
| FZ-Jülich | Forschungszentrum Jülich, Germany |
| GALION | GAW Aerosol Lidar Observation Network |
| GAMeS | Global Atmospheric Methane Synthesis |
| GAW | Global Atmosphere Watch |
| GAW-CCL | GAW Central Calibration Laboratory |
| GAWSIS | GAW Station Information System |
| GAWTEC | GAW Training and Education Centre |
| GC | Gas Chromatography |
| GCM | General Circulation Model |
| GCOS | Global Climate Observing System |
| GEF | Global Environment Facility |
| GEMS | Global and regional Earth-system Monitoring using Satellite and in situ data |
| GEO | Group on Earth Observations |
| GEOMON | Global Earth Observation and monitoring |
| GEOSS | Global Earth Observation System of Systems |
| GESAMP | Joint Group of Experts on the Scientific Aspects of Marine Environmental Protection |
| GHG | Greenhouse Gas |
| GLOBEC | Global Ocean Ecosystem Dynamics |
| GMES | Global Monitoring for Environment and Security |
| GOME | Global Ozone Monitoring Experiment |
| GOME2 | Global Ozone Monitoring Experiment 2 |
| GPCP | Global Precipitation Chemistry Programme |
| GSP | GAW Strategic Plan |
| GSRN | Global Surface Radiation Network |
| GTS | Global Telecommunication System |
| GTT | GURME Training Team |
| GURME | GAW Urban Research Meteorology and Environment Project |
| HALOE | Halogen Occultation Experiment |
| HCFC | Hydrochlorofluorocarbons |
| HFCs | Hydrofluorocompounds |
| HTAP | Hemispheric Transport of Air Pollution |
| IADV | Interactive Data Visualization |
| IAEA | International Atomic Energy Agency |
| IAGOS-MOZAIC | Integration of routine Aircraft Observations into a Global Observing System |
| IAI | Inter American Institute for Global Change Research |
| IAPSAG | International Aerosol Precipitation Science Assessment Group |
| ICSU | International Council for Science |
| ICTT QMF | Inter-Commission Task Team on Quality Management Framework |
| IFT | Institute for Tropospheric Research, Leipzig, Germany |
| IFU | Fraunhofer Institut fur Atmospharishe Umweltforschung, Garmisch-Partenkirchen, Germany |
| IGAC | International Global Atmospheric Chemistry Project |
| IGACO | Integrated Global Atmospheric Chemistry Observations |
| IGBP | International Geosphere-Biosphere Programme |
| IGOS | Integrated Global Observing Strategy |
| IGY | International Geophysical Year |
| IHALACE | International Halocarbon Intercomparison Experiment |
| ILAS | Improved Limb Atmospheric Spectrometer |
| iLEAPS | Integrated Land Ecosystem – Atmosphere Processes Study |
| IM | Inverse Modelling |
| IMBER | Integrated Marine Biogeochemistry and Ecosystem Research |
| IMK | Institut Für Meteorologie und Klimatologie |
| IMK-IFU | Institute for Meteorology and Climate Research of the Karlsruhe Institute of Technology, Garmisch-Partenkirchen, Germany |
| IMPROVE | Interagency Monitoring of Protected Visual Environments |
| IOC | International Ozone Commission |
| IPCC | Intergovernmental Panel on Climate Change |
| IPET-MI | Inter-Programme Expert Team on Metadata Implementation |
| IPY | International Polar Year |
| IRC | International Radiation Commission |
| ISAP | International Science Advisory Panel |
| ISO | International Organization for Standardization |
| ISWS | Illinois State Water Survey |
| IUGG | International Union of Geodesy and Geophysics |
| IUPAC | International Union of Pure and Applied Chemistry |
| IZO | Izaña Observatory, Tenerife, Spain |
| JGOFS | Joint Global Ocean Flux Study |
| JMA | Japan Meteorological Agency |
| JOSIE | Julich Ozone Sonde Intercomparison Experiments |
| JRC | Joint Research Centre of the European Commission, Ispra, Italy |
| JSC | Joint Scientific Steering Committee |
| JSC OPAG-EPAC | Joint Scientific Committee of the Open Area Programme Group on Environmental Pollution and Atmospheric Chemistry |
| LIDAR | Light Detection And Ranging |
| LRTAP | Long-range Transboundary Air Pollution |
| MEDPOL | Mediterranean Pollution Monitoring and Research Programme |
| MGO | Main Geophysical Observatory, St Petersburg, Russian Federation |
| MLS | Microwave Limb Sounder |
| MOHp | Meteorological Observatory Hohenpeissenberg, Germany |
| MOPITT | Measurements Of Pollution In The Troposphere |
| MOZAIC | Measurement of Ozone by Airbus In-service airCraft |
| MSC | Meteorological Service of Canada- formerly Atmospheric Environment Services (AES), Toronto, Canada |
| NADP | National Atmospheric Deposition Programme (in the United States of America) |
| NARSTO | North American Research Strategy for Tropospheric Ozone |
| NASA | National Aeronautics and Space Administration |
| NCEP | National Centres for Environmental Prediction |
| NDACC | Network for the Detection of Atmospheric Composition Change |
| NDSC | Network for the Detection of Stratospheric Change |
| NH | Northern Hemisphere |
| NILU | Norwegian Institute for Air Research |
| NIST | National Institute of Standards and Technology, Gaithersburg MD, USA |
| NMHS | National Meteorological and Hydrological Service |
| NOAA | National Oceanic and Atmospheric Administration, USA |
| NOMHICE | Non-Methane Hydrocarbon Intercomparison Experiment |
| NRT | Near-real-time, specifying observations ‘not older than 1-2 hours that can be incorporated into the data assimilation schemes of weather or air quality forecast models’ |
| NSF | National Science Foundation |
| NWP | Numerical Weather Prediction |
| OCBA | Observatorio Central Buenos Aires, Argentina |
| OCO | Orbiting Carbon Observatory |
| OMI | Ozone Monitoring Instruments |
| OMPS | Ozone Mapping and Profiler Suite |
| OPAG | Open Programme Area Group |
| OSG | Operations Support Group |
| PC | Precipitation Chemistry |
| PFR | Precision filter radiometer |
| PMOD/WRC | Physikalisch-Meteorologisches Observatorium Davos/World Radiation Centre, Switzerland |
| POAM | Polar Ozone and Aerosol Measurement |
| POPs | Persistent organic pollutants |
| QA | Quality Assurance |
| QA/QC | Quality Assurance/Quality Control |
| QA/SAC | Quality Assurance/Science Activity Centre |
| QAPjP | Quality Assurance Project Plan |
| QASUME | Quality Assurance of Spectral Measurements in Europe |
| QMF | Quality Management Framework |
| QMS | Quality Management System |
| RA | WMO Regional Association |
| RCC | Regional Calibration Centre |
| RDCC | Regional Dobson Calibration Centre |
| RG | Reactive Gases |
| SAG | Scientific Advisory Group |
| SAGE | Stratospheric Aerosol and Gas Experiment |
| SAWS | South African Weather Service, Pretoria, South Africa |
| SBUV | Solar Backscatter Ultraviolet Instrument |
| SCIAMACHY | Scanning Imaging Absorption SpectroMeter for Atmospheric ChartographY |
| SCOUT-O3 | Stratospheric-Climate links with emphasis On the Upper Troposphere and lower stratosphere |
| SH | Southern Hemisphere |
| SHADOZ | Southern Hemisphere Additional Ozonesondes programme |
| SMN | Servicio Meteorologico Nacional, Argentina |
| SOLAS | Surface Ocean – Lower Atmosphere Study |
| SOO-HK | Solar and Ozone Observatory Hradec Kralove, Czech Republic |
| SOOP | Ship-of-Opportunity Programme, a joint IOC-WMO programme |
| SOPs | Standard Operating Procedures |
| SPARC | Stratospheric Processes and Their Role in Climate |
| SRRB | Surface Radiation Research Branch of NOAA's Air Resources Laboratory (now part of NOAA ESRL) |
| STE | Stratosphere/Troposphere Exchange |
| SUNY | State University of New York |
| TCCON | Total Column Carbon Observing Network |
| TF HTAP | Task Force on Hemispheric Transport of Air Pollution |
| TOMS | Total Ozone Mapping Spectrometer |
| UARS | Upper Atmosphere Research Satellite |
| UBA | Umweltbundesamt/The Federal Environmental Agency, Germany |
| UFS | Umweltforschungsstation Schneefernerhaus |
| UNCED | United Nations Conference on Environment and Development |
| UNDP | United Nations Development Programme |
| UNECE | United Nations Economic Commission for Europe |
| UNECE-LRTAP | United Nations Economic Commission for Europe Convention on Long Range Transboundary Air Pollution |
| UNEP | United Nations Environment Programme |
| UNESCAP | United Nations Economic and Social Commission for Asia and the Pacific |
| UNFCCC | United Nations Framework Convention on Climate Change |
| UV | Ultraviolet Radiation |
| VCP | WMO Voluntary Co-operation Programme |
| VOCs | Volatile Organic Compounds |
| VOS | Voluntary Observing Ship |
| WCC | World Calibration Centre |
| WCCAC | World Calibration Centre for Aerosol Chemistry |
| WCCAP | World Calibration Centre for Aerosol Physics |
| WCCOS | World Calibration Centre for Ozone Sondes |
| WCP | World Climate Programme |
| WCRP | World Climate Research Programme |
| WDC | World Data Centre |
| WDCA | World Data Centre for Aerosols |
| WDCGG | World Data Centre for Greenhouse Gases |
| WDCPC | World Data Centre for Precipitation Chemistry |
| WDC-RSAT | World Data Centre for Remote Sensing of the Atmosphere |
| WHO | World Health Organization |
| WIDAC | World Integrated Data Archive Centre |
| WIGOS | WMO Integrated Global Observing System |
| WIS | WMO Information System |
| WMO | World Meteorological Organization |
| WOCE | World Ocean Circulation Experiment |
| WORCC | World Optical Depth Research and Calibration Centre |
| WOUDC | World Ozone and UV Data Centre |
| WRC | World Radiation Centre |
| WRDC | World Radiation Data Centre, St Petersburg, Russia |
| WRMC | World Radiation Monitoring Centre |
| WWRP | World Weather Research Programme |
| WWW | World Weather Watch Programme |
