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[NOAA bullet] AOGCM (Atmosphere/Ocean General Circulation Model or Atmosphere/Ocean Global Climate Model)

A numerical representation of the climate system based on the physical, chemical and biological properties of its components, their interactions and feedback processes, and accounting for all or some of its known properties. The atmosphere and ocean general circulation model components are three-dimensional, time-dependent models that include a representation of the equations of motion on a sphere. In addition to atmosphere and ocean components, the term AOGCM is often applied to computer models that include land surface and sea ice model components. The model components are coupled, in the sense that fluxes are regularly exchanged between the different model components as they march forward in time. AOGCMs provide a relatively comprehensive representation of the climate system. AOGCM models are applied, as a research tool, to study and simulate the climate, but also for operational purposes, including monthly, seasonal and interannual climate predictions.

[NOAA bullet] AR4 (Fourth Assessment Report of the IPCC)

The Fourth Assessment Report of the IPCC (aka AR4) is scheduled to be completed in 2007. See IPCC for more information.

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[NOAA bullet] CCSP (U.S. Climate Change Science Program)

The U.S. Climate Change Science Program integrates federal research on climate and global change, as sponsored by thirteen federal agencies and overseen by the Office of Science and Technology Policy, the Council on Environmental Quality, the National Economic Council and the Office of Management and Budget. CCSP retains the responsibility for compliance with the requirements of the Global Change Research Act of 1990, including its provisions for annual reporting of findings and short-term plans, scientific reviews by the National Academy of Sciences / National Research Council, and periodic publication of a ten-year strategic plan for the program. [The above information was taken from the CCSP web pages.]

[NOAA bullet] climate sensitivity (see equilibrium climate sensitivity)

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[NOAA bullet] deccen (decadal-to-centennial variability)

A term used to describe variations and changes in climatic elements occurring on time scale ranging from decades to centuries. These temporal variations may be induced by changes in forcing agents arising from either human activities (e.g., increasing levels of atmospheric greenhouse gases) or natural causes (e.g., volcanic aerosols or solar irradiance). Some deccen climate variability is unforced, in that it can be the product of internally generated climate system fluctuations.

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[NOAA bullet] ENSO (El Niņo - Southern Oscillation)

The ENSO acronym acknowledges the linkage between El Niņo events and the Southern Oscillation. The El Niņo/La Niņa aspect of ENSO refers to significant oscillations in sea surface temperature over the eastern and central equatorial Pacific. The Southern Oscillation is a "seesaw" in sea level pressure, with one center of action in the western Pacific-Indian Ocean region and the other in the eastern Pacific. The ENSO cycle occurs at irregular intervals, typically ranging between two and seven years, and probably is the best known and most studied si phenomenon.

[NOAA bullet] equilibrium climate sensitivity

The term equilibrium climate sensitivity commonly refers to the equilibrium change in global mean surface air temperature following a doubling of the atmospheric (equivalent) carbon dioxide concentration

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[NOAA bullet] ferret

Developed at NOAA's Pacific Marine Environmental Laboratory (PMEL), Ferret is an interactive computer visualization and analysis environment designed to meet the needs of oceanographers and meteorologists analyzing large and complex gridded data sets. [The above information was adapted from text presented on the Ferret web pages.]

[NOAA bullet] forcing & forcing agents

A forcing (or more properly, a radiative forcing) is the result of a process that directly changes the energy balance of the climate system by affecting the balance between incoming solar radiation and outgoing longwave and shortwave radiation. It does not include the effects of feedbacks. A positive forcing tends to warm the surface of the Earth and a negative forcing tends to cool the surface. Forcing agents, such as clouds, greenhouse gases, aerosols, and surface albedo changes, are those things that cause variations in radiative forcings.

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[NOAA bullet] GrADS (Grid Analysis and Display System)

Developed at the Center for Ocean-Land-Atmosphere Studies (COLA), GrADS is an interactive desktop tool that is used for easy access, manipulation, and visualization of earth science data. [The above information was adapted from text presented on the GrADS web pages.

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[NOAA bullet] IPCC (The Intergovernmental Panel on Climate Change)

The Intergovernmental Panel on Climate Change (IPCC) has been established by the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) to assess scientific, technical and socioeconomic information relevant for the understanding of climate change, its potential impacts and options for adaptation and mitigation. The IPCC is organized into three Working Groups and a Task Force. GFDL scientists are primary involved with Working Group I (WGI), which assesses the physical science aspects of the climate system and climate change. Model output from GFDL and other modeling centers is analyzed as part of both WGI and WGII activities. A main activity of the IPCC is to provide in regular intervals an assessment of the state of knowledge on climate change.
The IPCC has completed three assessment report cycles. The first was completed in 1990, the second in 1995 and the third in 2001. The fourth assessment report (AR4) is planned to be completed in 2007.[The above information was adapted from text presented on the IPCC web pages.]

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[NOAA bullet] PCMDI (Program for Climate Model Diagnosis and Intercomparison)

Located at the Lawrence Livermore National Laboratory (LLNL), PCMDI's mission is to develop improved methods and tools for the diagnosis and intercomparison of general circulation models (GCMs) that simulate the global climate. PCMDI is providing facilities for the storage and distribution of data sets from multiple coupled ocean-atmosphere GCM climate simulations, including those conducted at GFDL.Access to data stored on the IPCC/PCMDI archive (model output from GFDL and other international research centers) is limited to users whose registration applications are approved by the IPCC/WGCM committee. [The above information was adapted from text presented on the PCMDI web pages.]

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[NOAA bullet] si (seasonal-to-interannual variability)

Sometimes referred to as "short term climate fluctuations", si variability occurs on time scales longer than that associated with individual synoptic weather systems (i.e., beyond the range of credible day to day forecasts), up to time scales of a few years. The El Niño - Southern Oscillation (ENSO) is the phenomenon that is perhaps most often associated with si variability.

[NOAA bullet] SRES (Special Report on Emissions Scenarios)

In 2000, the IPCC published a Special Report on Emissions Scenarios (SRES), presenting multiple scenarios of greenhouse gas and aerosol precursor emissions for the 21st century. The SRES scenarios, some of which are used to drive climate model projections, cover a wide range of the main driving forces of future emissions, from demographic to technological and economic developments. [The above information was adapted from text presented on the IPCC SRES web pages & related pages at the University of East Anglia Climatic Research Unit.]

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[NOAA bullet] U.S. CCSP (see CCSP)

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[NOAA bullet] WGI (Working Group I of the IPCC)

One of three IPCC working groups, WGI focuses on the physical basis of climate change. [see The IPCC WGI web pages for additional information.]

(*) Some of the definitions on this page have been drawn from the following sources:

  • [book icon] Appendix I, Glossary from "Climate Change 2001: IPCC Working Group I: The Scientific Basis", Editor: A.P.M. Baede.

  • [book icon] Annex D., Glossary of Terms from "Strategic Plan for the Climate Change Science Program Final Report", U.S. CCSP and the Subcommittee on Global Change Research , July 2003.

  • [book icon] The American Meteorological Society's online Glossary of Meteorology.

Questions related to the GFDL CM2.x models may be directed to

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last modified: June 24 2019.