Ga-Gm

 

GAGE

Acronym for Global Atmospheric Gases Experiment. See ALE/GAGE/AGAGE.

 

Gaia hypothesis

The hypothesis that the Earth's physical and biological systems are considered to be a complex and self-equilibrating entity. See Lovelock (1979).

 

GAIM

Acronym for Global Analysis, Interpretation and Modelling, a subprogram of the the IGBP to analyze current models and data, assess the capability of current models and experimental programs to resolve key questions, and advance and sythesize our understanding of the global biogeochemical cycles and their links to the hydrological cycle and to the physical-climate system as a whole. See the GAIM Web site.

 

galactic circle

The great circle of the celestial sphere in where it is cut by the galactic plane. It is the primary circle to which the galactic coordinates are referred.

 

galactic plane

The plane passing as nearly as possible through the center of the belt known as the Milky Way or Galaxy.

 

GALE

Acronym for the Genesis of Atlantic Lows Experiment, an extensive study of the atmospheric processes involved in the development of winter storms on the East Coast of the United States. The planning phase ran from 1984-86, field operations during 1986, and the analysis phase from 1986-89. See Dirks et al. (1988).

 

GAME

Acronym for the GEWEX Asian Monsoon experiment, the goal of which is to understand the role of the Asian monsoon in the global climate system and develop methods for long-range forecasting. See the GAME Web site for further information.

 

GAMES

Acronym for Global Aerosols Monitoring Experiment from Space.

 

gap analysis

The evaluation of the management status of plant communities, vertebrate species and species richness by GIS overlay of biological distribution data on a map of existing biological reserves. First maps are produced at low spatial resolution to provide a broad overview of biota distribution and their management status and to identify landscapes that contain large numbers of potentially unprotected vegetation types and vertebrate species. Then the problem areas are studied in more detail as candidates for additional management and conservation efforts. See the UCSB Biogeography Laboratory Gap Analysis Project Web site.

 

GAPA

Acronym for the International Geological-Geophysical Atlases of the Atlantic and Pacific Oceans, an ocean mapping activity of the IOC.

 

GARP

Acronym for the Global Atmospheric Research Program, planned and coordinated jointly starting in 1968 by the WMO and the ICSU.

 

GASTON

Abbreviation for Glace Atmosphere sur Terre et Ocean Numeriques, a group performing numerical simulations of coupled ocean, atmosphere and ice models. For further details, see the GASTON Web site.

 

gas-to-particle conversion

In the study of atmospheric aerosols, GPC is a mechanism for the production of nucleation mode type atmospheric aerosols where condensation of gaseous substances causes either the growth of existing nuclei (heterogeneous nucleation) or the formation of new particles (homogeneous nucleation). The former can proceed at minor supersaturations while the latter requires a much greater degree of supersaturation. Converted sulfates, nitrates and hydrocarbons are three major components suspected of being involved in GPC. See Jaenicke (1993b).

 

Gastropoda

A class of marine invertebrates in the Phylum Mollusca. Most of these have a spiral shell and a foot used for creeping, although some are holoplanktonic without shells and with the foot modified for swimming, e.g. pteropods and heteropods. Most of the 49,000 species in this class are marine.

 

GATE

1. Acronym for GARP Atlantic Tropical Experiment. 2. Acronym for Global Acoustic Transmission Experiment.

 

Gauss Magnetic Epoch

Normal polarity time interval extending from 2.4 to 3.3 million years ago. See Bowen (1991).

 

Gaussian distribution

More about which later.

 

GAW

Acronym for the Global Atmospheric Watch program, established in 1989 by the WMO as a world wide system of atmospheric composition monitoring and research consisting of over 300 observation stations. The purpose is to provide data, scientific assessments, and other information on the atmospheric composition and related physical characteristics of the background atmosphere from all parts of the globe. The measurement program includes greenhouse gases, ozone, radiation and optical depth, precipitation chemistry, chemical and physical properties of aerosols, reactive gases, radionuclides, and related meterological parameters. See the GAW Web site.

 

GBRUC

Abbreviation for Great Barrier Reef Undercurrent.

 

GCATE

Acronym for Global Change and Terrestrial Ecosystems, an IGBP project.

 

GCCIP

Abbreviation for the Global Climate Change Information Programme, a program established in Oct. 1991 to provide an link for information about climate change among scientists, politicians, economists, and the general public. GCCIP is a part of ARIC. See the GCCIP Web site.

 

GCD

Abbrevation for General Circulation Drifter.

 

GCDC

Abbreviation for Global Change Data Center, a part of the NASA/GSFC's ESD whose mission is to develop and operate data systems, generate science products, and provide archival and distribution services for earth science data in support of the USGCP and the NASA MTPE. See the GCDC Web site for further information.

 

GCDIS

Acronym for Global Change Data and Information System, a proposed IWG structure that encompasses the ensemble of multi-agency and institution data and information systems supporting the Global Change Research Program (GCRP) and IGBP. GCDIS may be more broadly viewed as encompassing those who serve the GCRP and the IGBP. More information can be found at the GCDIS Web site.

 

GCEC

Abbreviation for Global Change and Ecological Complexity, an IGBP project.

 

GCFI

Abbreviation for Gulf and Caribbean Fisheries Institute.

 

GCIP

Abbreviation for GEWEX Continental-Scale International Project, a multifaceted group of activities designed primarily to improve scientific understanding and the ability to model, for climate prediction purposes, the coupling between the atmosphere and the land surface on a continental scale. GCIP is examining the energy budget and hydrological cycle of the Mississippi River watershed. See the GCIP Web site for further information, including volumes I, II, and III of the GCIP Implementation Plan.

 

GCM

See general circulation model.

 

GCMD

Acronym for Global Change Master Directory, an electronic information resource operated at NSSDC, providing brief information about space and earth science data and data sets. This is the American Coordinating Node of the CEOS IDN and also a participant in the UGGCRP. Free, online access allows users to identify relevant data sets and their location, and also allows direct connection to certain specific data centers. See the GCMD Web site.

 

GCOS

Acronym for the Global Climate Observing System, a global observing program planned jointly by ICSU, WMO, UNEP, and IOC of UNESCO. It was established to develop a dedicated observing system designed specifically to meet to observation requirements for monitoring climate, detecting climate change, and for predicting climate variations and change. The objectives of GCOS are to meet the observational needs for climate system monitoring, climate change detection and response monitoring, especially in terrestrial ecosystems; data for application to national economic development; and research toward improved understanding, modeling, and predicting the climate system. A Joint Scientific and Technical Committee (JSTC) and a Joint Planning Office (JPO) were set up to develop the plans and strategy for implementation of the system. See the GCOS Web site for more information.

 

GCPS

Acronym for Global Climate Perspectives System, a joint project between two NOAA laboratories (the NCDC and the CDC of the ERL) to study the existence and magnitude of climate changes on a global scale, create high-quality global climate reference datasets and provide access to them, and to crate a set of computer tools to aid in climate research. See the GCPS Web site.

 

GCRI

Abbreviation for the U.S. Greenhouse Climate Response Index, a means of possible early detection and monitoring of anticipated greenhouse-induced climate change in the U.S. It is calculated as the arithmetic average of four indicators:

1. The percent of the U.S. with much above normal minimum temperatures.
2. The percent of the U.S. with much above normal precipitation during the months October through April (the cold season).
3. The percent of the U.S. in extreme or severe drought during the months May through September (the warm season).
4. The percent of the U.S. with a much greater than normal proportion of precipitation derived from extreme 1-day precipitation events (exceeding 2 inches or 50.8 mm).

Much above and below normal are defined as falling within the highest and lowest tenth percentile of the local, long-term record. The GCRI has averaged 12.2% since 1976 (where the expected value for any given year is 10%), whichis 2.8% above the average from previous years in the century although not large or consistent enough to be rejected the statistical possibility that this increase is still a feature of a stable climate. See Karl et al. (1995) and Karl et al. (1996).

 

GCRIO

Acronym for Global Change Research Information Office, established under the GC Research Act of 1990 (Public Law 101-606) to provide United States generated scientific research information in the area of global change to foreign governments, businesses and institutions, and citizens of foreign countries. More information can be found at the GCRIO Web site.

 

GCRP

Abbreviation for Global Change Research Program.

 

GCSS

Abbreviation for the GEWEX Cloud System Study, a project to develop better parameterizations of cloud systems for climate models by an improved understanding of the physical processes at work within various types of cloud systems. More See Browning (1993), GEWEX Cloud System Science Team (1993) and the GCSS Web site.

 

GCTE

Abbreviation for Global Change and Terrestrial Ecosystems, an IGBP core project to develop the capacity to predict the effects of changes in climate, atmospheric composition, and land use practices on terrestrial ecosystems, and to determine feedback mechanisms to the physical climate system. The operational plan to meet its objectives is divided into a hierarchy of four foci: ecosystem physiology, change in ecosystem structure, global change impact on agriculture and forestry, and global change and ecological complexity. The first two foci are designed to provide a fundamental understanding of the impacts of global change on ecosystem function, composition and structure, and their feedback effects. The third and fourth are designed to examine the most specific impacts of global change on systems of great importance to humans.

There are four project level facilities beneath this formal research structure to integrate the GCTE research effort: (1) the Long-Term Ecosystem Modeling Activity (LEMA) network of modeling centers; (2) a set of major transects along environmental gradients such as temperature or precipitation; (3) an international network of intensive crop experimental sites to be used for studies of crop performances at various points in their environmental range; and (4) a set of experimental sites examining the impact of elevated CO2 on ecosystem function using FACE technology. See the GCTE Web site.

 

GDC

Abbreviation for Global Drifter Center.

 

GDEM

Abbreviation for General Digital Environmental Model, a four-dimensional (latitude, longitude, depth, and time) digital model of temperature and salinity for the North and South Atlantic, the Pacific, the Indian Ocean north of 40 S, the Arctic Ocean, the Mediterranean Sea, and the Black Sea. It consists of coefficients of mathematical expressions describing vertical profiles of temperature and salnity on a half degree latitude-longitude grid for seasonal and annual time frames, with the actual profiles generated by combining the coefficients with the equations. Some regions are being updated to 10 minute resolution. Data for creating the GDEM were obtained from the Master Oceanographic Observational Data Set (MOODS) as well as from the Levitus climatology. It is used by the U.S. Navy for most of its operational systems. See Teague et al. (1990).

 

GDP

Abbreviation for Global Drifter Program.

 

GDSIDB

Abbreviation for Global Digital Sea Ice Data Bank.

 

GEBA

Acronym for the Global Energy Balance Archive, a database developed at the Swiss Federal Institute of Technology for the worldwide instrumentally measured energy fluxes at the Earth's surface. See Ohmura et al. (1989) and the GEBA Web site.

 

GEBCO

Acronym for GEneral Bathymetric Chart of the Oceans, a map series established by Prince Albert I of Monaco in 1903. This is at present an activity of the IOC. The GEBCO Digital Atlas is now available on CD-ROM.

 

GEIA

Abbreviation for Global Emissions Inventory Activity, a program of the IGAC core project of the IGBP. Its goals include establishing a framework for developing and evaluating global emissions inventories, conducting a critical survey of existing emissions inventories of compounds of major importance in global atmospheric chemistry, and generating and publishing inventories for use by scientists worldwide. See the GEIA Web site.

 

GEK

Abbreviation for geomagnetic electrokinetograph.

 

Gelbstoff

Dissolved material in sea water that is resistant to bacterial attack. Its name comes from the yellow color it imparts to the water. Brown algae, the principal algae group growing in coastal waters of temperature and higher latitudes, excrete phenolic compounds. These polyphenols are converted into a brown polymer by secondary reactions with carbohydrates and proteins of algal origin. The properties of the resulting substance are identical with Gelbstoff. Its concentration in sea water is around 1 mg/l and it is removed mainly by precipitation since its phenolic nature renders it resistant to bacterial attack. This is also known as yellow substance or gilvin. See Riley and Chester (1971).

 

GEM

1. Acronym for the General Ecosystem Model. See Rastetter et al. (1991). 2. Acronym for the Global Emiliania Modeling Initiative, a program involving studies of carbon and sulphur fluxes as well as a large geological component. The EHUX project is part of the program.

 

GEMS

Acronym for Global Environment Monitoring System, established as part of UNEP's Earthwatch program in 1975 as a collaborative effort of the UN system to monitor and assess the global environment. The objectives of GEMS include to strengthen monitoring and assessment capabilities in participating countries, to increase the validity and comparability of environmental data and information, to produce global/regional assessments in selected fields and compile environmental information at the global level, and to provide early warnings on emerging issues of potential international importance. See the GEMS Web site.

 

genetic strategy

A unifying concept in ecology defined as a grouping of similar or analogous genetic characteristics which occur widely among species or populations and cause them to exhibit similarities in ecology. See Grime (1979).

 

GENIE

Acronym for Global Environmental Network for Information Exchange, a project to provide a user-sympathetic system for locating and accessing relevant information on global environmental change. See the GENIE Web site.

 

geodesy

The science concerned with the study of the shape and size of the earth in the geometrical sense and with the study of certain physical phenomena, such as gravity, in seeking explanation of fine irregularities in the earth's shape, and as such in inextricably linked with surveying and cartography.

 

GEODYME

Acronym for Geochemistry and Dynamics of the Mediterranean, an MTP Core Sub-project whose aims are to monitor the evolution of the physical and chemical characteristics of western deep water and the detect similar changes in the different Mediterranean basins, to describe and quantify transfer processes at air-land-sea interfaces, and to give a new picture of phytoplankton distribution, new production and chemical transfers. See the GEODYME Web site.

 

geological oceanography

More later. Compare to biological, chemical and physical oceanography.

 

geoid

A hypothetical, global, and continuous sea-level surface perpendicular to the direction of gravity at all points.

 

GEOS

Acronym for Geodynamics Experimental Ocean Satellite.

 

GEOSAT

Acronym for Geodetic Satellite. See Douglas and Cheney (1990).

 

GEOSCOPE

Abbreviation for the Interactive Global Change Encyclopedia, a project to demonstrate that satellite data and other geographic information can be of vital importance in monitoring the global environment. See the GEOSCOPE Web site.

 

GEOSECS

Acronym for Geochemical Ocean Sections Study, a global survey of the three-dimensional distribution of chemical, isotopic and radiochemical tracers in the ocean. The expeditions were in the Atlantic from July 1972 to May 1973; the Pacific from August 1973 to June 1974; and the Indian Ocean from December 1977 to March 1978. The GEOSECS data set is available online.

 

general circulation model

Generally a three-dimensional time-dependent model of the atmosphere and/or ocean circulation. The solution to a set of mathematical equations governing the motions of a layer of fluid on a spherical planet is numerically approximated on a three-dimensional discrete grid of points to obtain temperatures, velocities, rainfall, pressure and any of several other dependent variables that collectively comprise the state of the climate. Often abbreviated as GCM. See Washington and Parkinson (1986).

 

Generic Mapping Tools

A collection of around 50 UNIX tools that allow the manipulation and graphing of X-Y and X-Y-Z data sets and the output of the results in PostScript format. The data can be manipulated in many different ways and the results can be graphed on a multitude of projections, with just about every imaginable graph attribute amenable to modification. The plotting capabilities include creating basemap plots, plotting coastlines, filled continents, borders and rivers on maps, contouring gridded data, producing images from 2-D data sets, contouring raw data by triangulation, plotting histograms, plotting sector or rose diagrams, and more. Many projections are provided including conic, azimuthal and cylindrical types. A unique feature of GMT is the High-Resolution Coastline Database. This is a five resolution level database of world coastlines, rivers, lakes, and political boundaries. The maps included in the glossary were created using this package. GMT was written for UNIX systems in the C language as is freely available for academic use. See the GMT Web site.

 

GENESIS

The acronym for the Global Environmental and Ecological Simulation of Interactive Systems model developed by Starley Thompson and Dave Pollard at NCAR. It is a heavily modified version of the CCM1 model also developed at NCAR. See Thompson and Pollard (1994) and the GENESIS Web site.

 

Geophysical Fluid Dynamics Laboratory (GFDL)

A part of the NOAA ERL network whose research goal is to expand the scientific understanding of the physical processes that govern the behavior of the atmosphere and the oceans as complex fluid systems. See the GFDL Web site.

 

geopotential

The potential energy per unit mass of a body due to the Earth's gravitational field as referred to an arbitrary zero reference level. A unit of geopotential is the potential energy acquired by a unit mass on being raised a unit distance in a gravitational field of unit strength.

 

geopotential distance

See dynamic height.

 

geopotential height

See dynamic height.

 

geopotential surface

A surface to which the force of gravity is everywhere perpendicular and equal. No work is necessary for the displacement of mass along a potential surface as long as no other forces act in addition to gravity. This can also be defined as a surface of equal dynamic height below the level of the sea surface, using the ideal sea surface level as a reference surface with the potential value 0. This has also been called a potential surface or a level surface.

 

geopotential thickness

See dynamic height.

 

geostationary orbit

An orbit lying above the Equator in which an artifical satellite moves at the same speed as the Earth rotates. As such it maintains position above the Earth's surface. Such satellites have an altitude of 35,910 km. Satellites in this type of orbit have a continuous view of the full disc of the Earth, although the curvature of the Earth makes it diffucult to gather information for latitudes higher than about 45-50 . They have a better time resolution than polar orbiting satellites, but are restricted to a single location.

 

geostrophic approximation

The use of the geostrophic wind as an approximation to the actual wind.

 

geostrophic balance

A balance between the Coriolis acceleration and the pressure gradient (divided by the density) in a rotating fluid subject to gravitational restoring forces.

 

geostrophic current

In oceanography, the theoretical current resulting from the balance of the pressure gradient force and the geostrophic force, i.e. the forces associated with horizontal changes in density are compensated by accelerations arising from fluid motion on a rotating Earth. Analogous to the geostrophic wind in meteorology.

 

geostrophic force

A virtual force used to account for the change in direction of the wind relative to the Earth's surface. It results from the Earth's rotation and the Coriolis force.

 

geostrophic method

See dynamic method.

 

geostrophic turbulence

To be completed.

 

geostrophic velocity

Those velocities inferred from measurements of the oceanic density field. These are construed to be those velocities that result from a geostrophic balance of forces in the ocean.

 

geostrophic wind

In meteorology, the theoretical wind resulting from the balance of the pressure gradient force and the geostrophic force. Analogous to the geostrophic current in oceanography.

 

geosynchronous

An orbit where the period of the satellite is equal to the period of the rotation of the Earth. This is usually used synonymously with geostationary, although the latter has the additional qualities of being circular and in the equatorial plane.

 

Geosynchronous Operational Environmental Satellite

A series of NOAA satellites used for geostationary remote sensing. See the GOES Web site. There is also a SSEC GOES Web site with further edifying information.

 

Gerard barrel

A barrel used to collect water samples in oceanography that holds 250 l.

 

Gerstner wave

A wave theory developed for periodic waves of finite height to surpass the limitations of Stokes wave theory. The equations are simple to use and the solutions are exact and satisfy continuity as well as the pressure conditions at the water surface, and experimental studies have shown that the theory closely approximates the profiles of real waves on a horizontal bottom. Drawbacks include that mass transport is not predicted, the velocity field is rotational, and the particle movements are opposite to that expected in real waves (and found in other theories).

The predictions of both Gerstner and Stokes wave theories agree equally well with measured wave profiles. This is well explained by the fact that if the Gerstner wave equations are expanded into a series the first three terms are identical to those in the Stokes solution. This similarity in predictive ability and greater ease of use lead to the preferential use of Gerstner wave theory in many engineering applications where its limitations are not significant. This has also been called trochoidal wave theory since the elevation profile takes the form of a trochoidal curve. See Komar (1976) and LeMehaute (1976).

 

GESAMP

Acronym for Joint Group of Experts on the Scientific Aspects of Marine Pollution, a group comprising elements from IMO, FAO, UNESCO-IOC, WMO, WHO, IAEA, UN and UNEP.

 

GEWEX

Acronym for the Global Energy and Water Cycle Experiment. Initiated in 1988 by the WCRP to observe and model the hydrologic cycle and energy fluxes in the atmosphere, at the land surface, and in the upper oceans. It is an integrated program of research, observations, and science activities leading to the prediction of global and regional climate change.

GEWEX hydrometeorology and land-surface projects include the GRDC, ISLSCP, GCIP, BALTEX, GAME, LBA, and MAGS. Radiation projects include the BSRN, CPRP, GPCP, GVaP, ISCCP, and SRB. Modeling and prediction projects are GCSS, G-NEP and PILPS. See the GEWEX Web site.

 

GFDL

Abbreviation for Geophysical Fluid Dynamics Laboratory.

 

GGI

Abbreviation for GPS Geoscience Instrument.

 

GHCC

Abbreviation for Global Hydrology and Climate Center.

 

GHCN

Abbreviation for the Global Historical Climatology Network, a comprehensive global baseline climate data site comprised of land surface station observations of temperature, precipitation, and pressure. All data are on a monthly basis with the earliest record dating from 1697. See the GHCN Web site.

 

giant squid

See Architeuthis princeps.

 

Gibb's phenomenon

An artifact of attempting to approximate a function or waveform with a discontinuity using a Fourier series or some other global, continuous basis function. The fit is poor in a region near the discontinuity, usually characterized by large oscillations within the region. Increasing the number of components in the approximation decreases the region of poor fit, which theoretically vanishes with an infinite number of components.

 

Gibraltar Experiment

See Kinder and Bryden (1987).

 

Gilbert Magnetic Epoch

Reverse polarity time interval extending from 3.3 to 4.5 million years ago. See Bowen (1991).

 

Gilsa Magnetic Event

Short-term normal polarity time interval about 1.6 million years ago within the Matuyama Reverse Epoch. See Bowen (1991).

 

gilvin

See Gelbstoff.

 

GIMMS

Acronym for Global Inventory Monitoring and Modeling Studies.

 

GIN Sea

Abbreviation for Greenland/Iceland/Norwegian Sea, an area that has also variously been called the Norwegian Sea and the Nordic Seas. The GIN Sea together with the Polar Sea constitute the Arctic Ocean in some classification schemes in contrast to others including the GIN Sea within the confines of the Atlantic. The former may perhaps be preferred for geomorphological as well as hydrographical reasons. The bottom is continuously oceanic in crust and depth through the connecting passage (to the north) of Fram Strait, while the southern connection is over a continental ridge, i.e. the Greenland-Scotland Ridge. Also, the deep thermohaline circulation processes of the GIN and the Polar Sea are closely linked.

The GIN Sea comprises two major basins: the Greenland Basin and the Greater Norwegian Basins (i.e. the Norwegian Basin and the Lofoten Basin) separated by the Mohn Ridge. It has six open boundaries through which important exchanges occur: Fram Strait connecting to the Polar Ocean to the north, three boundaries over the Greenland-Scotland Ridge that connect with the Atlantic Ocean, and two boundaries connecting to continental shelf seas, i.e. the North Sea and the Barents Sea. See Hopkins (1991).

 

GIPME

Acronym for Global Investigation of Pollution in the Marine Environment, an international cooperative program of scientific investigation focused on marine contamination and pollution. It is co-sponsored by the IOC, UNEP and IMO. The objectives of GIPME are to create authoritative evaluations of the state of the marine environment at both regional and global levels, to identify the requirements for measures to prevent or correct marine pollution, and to create procedures for assessing and improving compliance and surveillance monitoring of conditions and effects in the marine environment. See the GIPME Web site.

 

GISP

Acronym for Greenland Ice Sheet Project. See the GISP Web site.

 

GISS

An acronym for the Goddard Institute for Space Studies. This is also used to refer to the atmospheric GCM developed and used at that institution. See the GISS Web site.

 

GIST

Acronym for GCIP Integrated Systems Test, a data system test taking place in the Arkansas-Red River basins prior to the start of the 5 year GCIP Enhanced Observing Period (1995-2000). The objectives are to: (1) demonstrate the adequacy of the GCIP data collection and management system and (2) rectify any data system modifications identified in time for use in the Enhanced Observing Period. The GIST data sets can be accessed via CODIAC.

 

glacial

A time when ice sheets expand and average global climates are cooler and drier than during and interglacial.

 

Glacial Geology and Geomorphology

An electronic journal of the British Geomorphological Research Group. Selected papers are available online at the GGG Web site.

 

Glacial North Atlantic Deep/Intermediate Water

See Yu et al. (1996).

 

glacial period

A time interval during which ice sheets have spread widely across lowlands in the north. During the last million years there have been four major glacial periods. In chronological order they are the Nebraskan, the Kansan, the Saale, and the Warthe-Weischel.

 

glacier zones

A system for classifying zones on glaciers according to ice temperature and the amount of surface melting. The zones are dry snow zone, percolation zone, soaked zone, superimposed ice zone and ablation zone. See Paterson (1969).

 

GLAS

Abbreviation for the Geoscience Laser Altimeter System, an EOS instrument planned for the ALT platforms. It is a nadir-pointed laser altimeter which can measure cloud heights and aerosol vertical structure. See Cohen et al. (1987).

 

glendonite

A pseudomorph after a carbonate (ikaite) that is taken in paleothermometry to reflect cold subaqeuous depositional conditions. Ikaite characteristically grows in cold water sediments that are rich in organic matter, highly alkaline, reducing, and have a high hydrostatic pressure.

 

GLERL

Acronym for Great Lakes Environmental Research Laboratory.

 

GLFS

Abbreviation for Great Lakes Forecasting System.

 

GLI

Abbreviation for Global Imager, a spaceborne optical sensor designed for observing reflected solar radiation from the earth's surface. It is an ocean color sensor used for measuring the distribution of chlorophyll, vegetation biomass, distribution of snow and ice, albedo of snow and ice, and several other quantities. GLI has 22 bands in the visible and near-infrared regions, 5 bands in the shortwave infrared region, and 7 bands in the middle and thermal infrared regions for a multispectral imaging capability. The ground resolution ranges from 250 to 1000 meters with a swath width of 1600 in the cross-track direction. See the GLI Web site.

 

GLIMS

Acronym for Global Land Ice Monitoring from Space, a project designed to monitor the world's glaciers using data primarily from the ASTER intrument. See the GLIMS Web site.

 

GLIS

Acronym for Global Land Information System, an interactive computer system developed by the USGS for scientists seeking sources of information about the Earth's land surfaces. See the GLIS Web site.

 

Global Backscatter Experiment

Initiated in 1986, the GLOBE is a cooperative interagency and international research program to characterize the spatial, temporal and spectral variability of atmospheric aerosol backscatter coefficients. See the GLOBE Web site.

 

global change

A transformation which occurs on a world-wide scale (for example, an increase in CO2 in the atmosphere) or exhibits sufficient cumulative effects to have world-wide impact (for example, local species extinction resulting in global loss of biodiversity).

 

Global Drifter Center (GDC)

An AOML data center located in Miami, Florida that manages the deployment of drifting buoys around the world. Global Lagrangian Drifters (GLD) are placed in areas of interest using research ships, VOS, and U.S. Navy aircraft. Once they are operationally verified, the data is telemetered to the GDS and disseminated to interested parties everywhere. See the GDC Web site.

 

Global Drifter Program (GDP)

A NOAA AOML program whose objectives are to: (1) described mixed-layer velocity on a 5 degree resolution global basis and produce new charts of seasonal surface circulation; (2) provide an operational data stream for SST, sea level pressure, and surface velocity data; (3) verify global climate models; (4) compute single particle diffusivities, eddy statistics, and interannual to annual variability; (5) construct models of wind-driven currents; and (6) obtain high resolution coverage in special regions for process studies. The program was started in 1978. See the GDP Web site.

 

global electrical circuit

See atmospheric electrical circuit.

 

Global Energy and Water Cycle Experiment

GEWEX was initiated in 1988 by the WCRP as a program designed to observe and model the hydrologic cycle and energy fluxes in the atmosphere, at the land surface, and in the upper oceans. The International GEWEX Project Office (IGPO) is the focal point for the planning and development of all GEWEX projects and activities. See Chahine (1992a) and Chahine (1992b) and the GEWEX Web site for further information.

 

Global Geocryological Database

An internationally distributed system of linked data centers or nodes containing information from regions of perenially and seasonally frozen ground. The purpose of this IPA project is to help identify, acquire and disseminate data on permafrost and frozen ground. See the GGD Web site.

 

Global Hydrology and Climate Center

A research center, abbreviated GHCC, whose objective is to address global hydrological processes. See the GHCC Web site.

 

Global Precipitation Climatology Project

A GEWEX-affiliated project, abbreviated GPCP, designed to provide global data sets of area, time-averaged precipitation for a minimum period of 10 years (1986-1995). This data will be produced by merging geostationary and polar-orbiting satellite microwave and infrared data with rain gauge data from more than 6000 stations. More information can be found at the GPCP Web site.

 

global radiative-convective feedback

A feedback loop that links the hydrologic cycle and the ARC. This is a negative feedback that works on the principle that stronger convection leads to more high clouds, which reduces the ARC, further reducing the precipitation rate adn the level of convective activity. See also radiative-dynamical-convective feedback. See Wielicki et al. (1995).

 

Global Runoff Data Center

A GEWEX project, abbreviated GRDC, to compile a global data base of stream flow data for the development and verification of atmospheric and hydrologic models. More information can be obtained at the GRDC Web site.

 

Global Terrestrial Observing System

The GTOS is a global observing program planned jointly by FAO, UNESCO, ICSU, WMO, and UNEP.

 

Global Warming Potential (GWP)

The GWP is an index of the strength of the radiative forcing induced by greenhouse gases. It is defined in the IPCC Report Shine et al. (1990) as the time-integrated commitment to climate forcing from the instantaneous release of 1 kg of a trace gas expressed relative to that from 1 kg of carbon dioxide, i.e. it is the ratio of the warming caused by a substance to the warming caused by a similar mass of carbon dioxide with the GWP of CO defined as unity.

 

GLOBE

1. Acronym for the Global Backscatter Experiment. 2. Acronym for the Global Land One-kilometer Base Elevation GlobalLandOne project, an international effort to develop a best-available global digital elevation map on a 1-kilometer grid. See the GLOBE Web site. 3. Acronym for the Global Learning and Observations to Benefit the Environment program, a national and internationalhands-on environmental science and education program. It uses scientific instruments and state-of-the-art technology to make science relevant to todays K-12 students. See the GLOBE Web site.

 

GLOBEC

Acronym for Global Ocean Ecosystem Dynamics, a component of the IGBP developed and sponsored by SCOR, the IOC, the ICES, and PICES. Its goal is advance our understanding of the structure and functioning of the global ocean ecosystem, its major subsystems, and its response to physical forcing to where we can develop and capability to forecast the marine upper trophic system response to scenarios of global change. GLOBEC concentrates on zooplankton population dynamics and its response to physical forcing in pursuit of this goal. See the GLOBEC Web site or the U.S. GLOBEC Web site.

 

globigerina ooze

A type of calcareous ooze composed of the shells of unicellular creatures called globigerina that live in the waters of warmer ocean regions. These oozes are seldom found above 5000 m depth and cover about 35% of the surface of the sea floor. See Neumann and Pierson (1966) and Tchernia (1980).

 

GLOBIS

Acronym for Global Change and Biodiversity in Soils.

 

GLOCARB

Acronym for Global Tropospheric Carbon Dioxide Network.

 

GLOCHANT

Acronym for Global Change Research in the Antarctic.

 

GLOCHEM

Acronym for Global Atmospheric Chemical Survey.

 

GLOCOPH

Acronym for Global Continental Palaeohydrology Project, an activity of INQUA.

 

Gloger's Rule

An ecogeographical rule that states that races of warm-blooded animals in warmer regions are more darkly colored than races in colder or drier regions. It was established by Contantin Wilhelm Lambert Gloger in 1833.

 

GLOMAC

Acronym for Global Modeling of Atmospheric Chemistry, a EUROTRAC program to develop a three dimensional model of the global troposphere for simulating the transport and transformation of trace constituents, and to use the model to answer questions concerning the sources and sinks of tropospheric ozone and its precursors, the influence of anthropogenic processes on composition and climate, and the long-range transport of sulfur compounds and other acidifying substances. See the GLOMAC Web site.

 

GLOMEX

Acronym for Global Meteorological Experiment.

 

GLONET

Acronym for Global Tropospheric Ozone Network, an IGAC activity.

 

GLORI

Acronym for Global Land-Ocean River Inputs database.

 

GLOSS

Acronym for the Global Sea Level Observing System, an IOC-coordinated project for the establishment of a strategic gloval core network of about 300 tide gauges around the world for long term climate change and oceanographic sea level monitoring. These gauges are spaced about 1000 km apart along coastlines and on oceanic islands and provide hourly-resolution standardized sea level data. See the GLOSS Web page.

 

GLRS

Abbreviation for Geoscience Laser Ranging System.

 

glycophytes

Plants intolerant to salinity.

 

glycohalophytes

Plants able to withstand moderate salinity, i.e. adapted to high osmotic potentials in soil water.

 

GMCC

Abbreviation for Geophysical Monitoring of Climate Change, an ARL program.

 

GMCSS

Abbreviation for Global Multi-region Cloud System Study.

 

GMP

Abbreviation for Gulf of Mexico Program.

 

GMT

1. Abbreviation for Greenwich Mean Time. 2. Abbreviation for Generic Mapping Tools.