Ca-Cm

 

C3 plant

Any plant that uses the C biochemical pathway for fixing carbon dioxide which involves the enzyme ribulose-diphosphate carboxylase. Approximately 95% of the Earth's plant biomass is accounted for by C3 plants.

 

C4

Abbreviation for the Center for Clouds, Chemistry and Climate, an organization whose goal is to develop the theoretical, observational, and modeling base required to understand and predict the changing clmiate and chemistry of Earth's atmosphere due to natural causes and human activities. A major objective is to unravel the role of clouds in climate and chemistry. C4 is located at the Scripps Institution of Oceanography. The C4 members designed, implemented, and analyzed the results of the CEPEX experiment. See the C4 Web site.

 

C4 plant

Any plant that uses the C biochemical pathway for fixing carbon dioxide which involves the enzyme phospho-enol-pyruvate carboxylase. Approximately 5% of the Earth's plant biomass is accounted for by C4 plants, although a number of plants of importance to humans (e.g. maize) are included in this category.

 

caballing

See cabbeling.

 

cabbeling

In physical oceanography, a phenomenon that occurs when two water masses with identical densities but different temperatures and salinities mix to form a third water mass with a greater density than either of its constituents. This is hypothesized to be a major cause of sinking in high northern latitudes. See McDougall (1987).

 

CAGEX

Acronym for CERES/ARM/ GEWEX Exercise, intended to foster the development of algorithms for the retrieval of vertical profiles of broadband radiative fluxes from satellite data. See the CAGEX Web site.

 

Calabrian

The single age of the Pleistocene epoch, lasting from 1.6 to 0.01 Ma. It is preceded by the Piacenzian age and followed by the Holocene epoch.

 

calcareous

Of or containing calcium carbonate or another, usually insoluble, calcium salt.

 

calcareous ooze

A fine-grained, deep-sea deposit of pelagic origin containing more than 30% calcium carbonate derived from the skeletal material of various plankton. It is the most extensive deposit on the ocean floor but restricted to depths less than about 3500 m due to the carbon compensation depth.

 

CALCOFI

Acronym for California Co-operative Fisheries Investigations. See the CALCOFI Web site.

 

California Current

The eastern limb of the clockwise flowing subtropical gyre in the North Pacific. This, like the Peru Current is a region of upwelling although the winds and therefore the upwelling in this region are more highly variable. The average (with a large standard deviation) transport has been estimated at around 11 Sv. From about October to March the prevailing winds are southeasterly which causes poleward flow at the surface over the shelf and even further offshore. This seasonal flow, reaching a peak speed of 0.2-0.3 m/s in January and February, is sometimes called the Davidson Current. From April until September northerly winds prevail which leads to upwelling and equatorward surface flow through the spring and summer months. This leads to an extremely large temperature gradient between a few kilometers offshore and the land surface with concomitant condensation and the sort of heavy fogs for which San Francisco is notorious. See Tomczak and Godfrey (1994).

 

CALK

Acronym for Carbonate ALKalinity, a function of carbonate and bicarbonate ion concentration.

 

Cambrian

The earliest period of the Paleozoic era, lasting from 570 to 505 Ma and preceding the Ordovician period. It is comprised of the Early (570-540 Ma), Middle (540-523 Ma), and Late (523-505 Ma) epochs. Named after the Roman name for Wales, the strata of this period contain the oldest system of rocks in which abundant fossils are usable for dating and correlation. Most invertebrate groups are present with trilobites and brachiopods most numerous.

 

Campanian

The fifth of six ages in the Late Cretaceous epoch, lasting from 84.0 to 74.5 Ma. It is preceded by the Santonian age and followed by the Maastrichtian age.

 

Canadian Hydrographic Service

An organization that produces hydrographic maps of Canadian coastal and inland waters for shipping and recreational boat communities. See the CHS Web site.

 

Canary Current

More later.

 

capacitance matrix method

An algorithm for imposing additional conditions on the solution of a boundary value elliptic problem at specified grid points in the interior of the computational domain. It effectively determines a modification to the right-hand side of the governing elliptic equation which will precisely satisfy the additional interior boundary conditions. Pragmatically it allows the inclusion of island and irregular coastal boundaries while retaining the use of fast and accurate elliptic solving routines at a modest additional computational expense. See Wilkin et al. (1995).

 

CAPE

Abbreviation for convective available potential energy.

 

capillary wave

A wave on a fluid interface for which the restoring force is surface tension.

 

carbon-14

The radioactive isotope of carbon, also called radiocarbon, than can be used for dating materials that contain carbon. Carbon-14 is produced in the atmosphere by a reaction between slow cosmic ray neutrons and stable nitrogen-14 and subsequently becomes incorporated into molecules of carbon dioxide by reactions with oxygen or be exchange reactions with stable carbon isotopes in molecules of carbon monoxide or carbon dioxide. These molecules are rapidly mixed through the atmosphere and hydrosphere to reach a constant level of concentration representing a steady-state equilibrium, maintained by the previously detailed constant production of radiocarbon and its continuous decay.

The carbon-14 molecules enter plants tissues via photosynthesis or by absorption through roots and the concentration subsequently remains constant due to a balance between incorporation and decay. Animals feeding on such plants have a similar constant radiocarbon level. When the plants and animals die, the incorporation phase stops while the decay continues. Thus if the radiocarbon activity in a living plant or animal is known, its activity in the dead tissues of a similar plant or animal can be used to calculate the time elapsed since its death. This is known as the carbon-14 date of the sample. See Bowen (1991).

 

carbon compensation depth

The level in the ocean below which the solution rate of calcium carbonate exceeds its deposition rate. This is also called the carbonate compensation depth.

 

carbon cycle

Refers to the cycling of carbon in the form of carbon dioxide, carbonates, organic compounds, etc. between various reservoirs, e.g. the atmosphere, the oceans, land and marine biota and, on geological time scales, sediments and rocks. The largest natural exchange fluxes occur between the atmosphere and the terrestrial biota and between the atmosphere and the surface water of the oceans.

 

carbon dating

Carbon dioxide in the atmosphere contains a constant proportion of radioactive C14 formed by cosmic radiation. Living organisms uptake this isotope in the same proportion via respiration. After the organism expires, it decays with a half-life of 5570 years to C12. The proportion of C12 to C14 gives the period elapsed since the expiration of the organism. See the excellently done Radiocarbon Web site for all the gory details.

 

carbon dioxide

This is the most important of the greenhouse gases with an atmospheric concentration of 353 ppm (in 1990), up from an estimated 260-290 in pre-industrial times (pre-1880). This gas plays a very large part in the natural carbon cycle, with the amount of carbon taken out of the atmosphere each year by plant photosynthesis being almost perfectly balanced by the amount put back into the atmosphere by the processes of animal respiration and plant decay.

The chief natural sources the burning of coal, oil and natural gas, the so-called fossil fuels, and the cutting down and burning of forests, with the latter contributing about a third as much as the former.

 

carbon dioxide fertilization

A probable feedback effect of the terrestrial biosphere-atmospheric carbon system where elevated levels of CO2 increase the productivity of natural ecosystems. This would cause more CO2 to be stored in woody tissue or soil organic matter and thus serve as a negative feedback on the atmospheric CO2 increase. This is also known as the fertilization effect.

 

carbonate pump

The name given to the cycling of CaCO3 in the ocean. Plants and animals living in the euphotic zone have CaCO3 skeletons (tests) which they precipitate from dissolved calcium and carbonate ions. The CaCO3 formed this way eventually sinks and is dissolved back to calcium and carbonate ions in the deeper parts of the water column and in the sediments. The ocean circulation closes the loop by transporting the ions back to the surface waters. This pump creates a surface depletion and a deep enrichment of both DIC and alkalinity. An increase in the strength of this pump will serve to increase atmospheric CO2 since the pump variations have twice as great an effect on alkalinity as on DIC. See Najjar (1991).

 

Carboniferous

The penultimate period of the Paleozoic era, lasting from 360 to 286 Ma. It precedes the Permian period and follows the Devonian period, and is comprised of the Early (360-320 Ma) and Late (320-286 Ma) epochs which coincide with, respectively, the Mississippian and Pennsylvanian sub-systems into which it is also divided. It is so named due to the widespread occurrence of carbon in the form of coal in layers of this period.

 

CARDS

Acronym for the Comprehensive Aerological Reference Data Set, a DOE and CGCP program providing a high quality global upper air database containing daily rawinsonde observations from 1948-1990. This also contains an upper air station history for 2400+ stations. See the CARDS Web site.

 

Caribbean Current

More later.

 

Caribbean Sea

Much more later.

 

Carruthers residual current meter

A current meter designed to measure and record the residual current over a longer period of time. In a manner similar to that of the Ekman current meter, a device drops small metal balls into a compass box after a certain number of turns of the propeller. The average velocity and direction are obtained by counting, after an extended period of time, the number and distribution of balls dropped (of over 22,000 available) into the slots of the compass box. See Sverdrup et al. (1942).

 

cartography

The science of mapmaking. A separate glossary of cartographic terms is available on the Web.

 

CAS

1. Abbreviation for Commission for Atmospheric Sciences. 2. Abbreviation for Canopy Air Space.

 

Caspian Sea

More later.

 

CASPR

Abbreviation for the Cloud and Surface Parameter Retrieval System, a toolkit for the analysis of data from the AVHRR satellite sensor carried on NOAA polar-orbiting satellites. See the CASPR Web site.

 

CAST

Acronym for the Center for Air Sea Technology, a program whose emphasis is on application of numerical ocean models and modeling techniques toward realistic simulation of ocean conditions, particularly the physical and dynamic state of coastal waters and semi-enclosed seas. See the CAST Web site.

 

CCALMR

Abbreviation for Commission for the Conservation of Antarctic Marine Living Resources.

 

CCC

Abbreviation for Canadian Climate Centre, located at Downsview, Ontario, Canada.

 

CCD

1. Abbreviation for Calcite Compensation Depth, defined as the depth at which the CaCO3 content of sediments reaches 20%. 2. Abbreviation for the Climate Change Detection Project, a WCDMP project that aims to provide regular assessments and authoritative statements on the interpretation and applicability of databases for the detection of climate change on global and regional scales. See the CCD Web site for more information.

 

CCDD

Abbreviation for the Climate Change and Data and Detection project, a NOAA OGP program element that provides data and information management support for a variety of national and international programs (e.g. GEWEX, WOCE, GCOS, GOALS, etc.), documents the quantitative character of observed climate variations and changes, and attributes changes in the observed record to specific climate forcings. See the CCDD Web page.

 

CCGCR

Abbreviation for the Centre for Climate and Global Change Research, located at McGill University in Canada. See the CCGCR Web site.

 

CCIX

Abbreviation for Climatic Change Information Exchange, an attempt to open and broaden the channels of communication between climate model owners and users of their information. It is intended to be used as an electronic library or clearinghouse for climatic change information. See the CCIX Web site.

 

CCM

The abbreviation for the Community Climate Model, an atmospheric GCM developed at NCAR. See the CCM Web site.

 

CCN

Abbreviation for cloud condensation nuclei, particles that serve to nucleate cloud drops in clouds.

 

CCRS

Abbreviation for the Canada Center for Remote Sensing, a national center responsible for the acquisition of remotely sensed data and for the development of remote sensing applications and related methodologies and systems. See the CCRS Web site.

 

CCSR

Abbreviation for the Center for Climate System Research, located at the University of Tokyo.

 

CDC

Acronym for the Climate Diagnostics Center, a part of the ERL component of the OAR office of NOAA. Their mission is to conduct diagnostic studies of climate on time scales of months to centuries. More information can be found at the CDC Web site.

 

CDEP

Acronym for the Climate Dynamics and Experimental Project, a NOAA OGP initiative to establish a program for quantitative predictions and reliable assessments of global climate change and its regional implications on time scales of seasons to a century. See the CDEP Web page.

 

CDIAC

Acronym for Carbon Dioxide Information and Analysis Center, an archive at ORNL containing data pertaining to atmospheric and climate change. See the CDIAC Web site.

 

CDW

Abbreviation for Circumpolar Deep Water.

 

CEES

Acronym for Committee on Earth and Environmental Science.

 

CEI

Abbreviation for the U.S. Climate Extremes Index, the annual average of five indicators. In all of the following much above or much below normal are defined as falling within the highest or lowest tenth percentile of the local, long-term record. These are

1. The sum of (a) the percent of the U.S. with maximum temperatures much below normal and (b) the percent of the U.S. with maximum temperatures much above normal.
2. The sum of (a) the percent of the U.S. with minimum temperatures much below normal and (b) the percent of the U.S. with minimum temperatures much above normal.
3. The sum of (a) the percent of the U.S. in severe drought (equivalent to the lower ten percentile) based on the PDSI and (b) the percent of the U.S. with severe moisture surplus (equivalent to the upper ten percentile) based on the PDSI.
4. Twice the value of the percent of the U.S. with a much greater than normal proportion of precipitation derived from extreme 1-day precipitation events (more than 2 inches or 50.8 mm).
5. The sum of (a) the percent of the U.S. with much greater than normal number of days with precipitation and (b) the percent of the U.S. with much less than normal number of days with precipitation.

The long-term variation or change of this index represents the tendency for extremes of climate to either decrease, increase, or remain the same. See Karl et al. (1995) and Karl et al. (1996).

 

Celebes Sea

Alternate name for the Sulawesi Sea.

 

celestial equator

The great circle in which the plane of the Earth's equator cuts the celestial sphere; the primary circle to which the coordinates, right ascension and declination are referred.

 

celestial latitude

The angular distance of a body north or south of the ecliptic.

 

celestial longitude

The arc of the ecliptic intercepted between the latitude circle and the First Point of Aries. It is measured positively eastwards from 0 to 360 deg. .

 

celestial mechanics

The study of the motions of celestial objects in gravitational fields. A perturbing subject.

 

celestial poles

The two points in which the Earth's axis, extended indefinitely, cuts the celestial sphere.

 

celestial sphere

An imaginary sphere, of indeterminate radius, in which the observer is the center.

 

CEMP

Abbreviation for CCAMLR Ecosystem Monitoring Program.

 

Cenomanian

The first of six ages in the Late Cretaceous epoch, lasting from 97.5 to 91.0 Ma. It is preceded by the Albian age of the Early Cretaceous epoch and followed by the Turonian age.

 

Cenozoic

The last of three eras of the Phanerozoic eon, lasting from 66.4 Ma to present. It is preceded by the Mesozoic era and consists of the Tertiary and Quaternary periods.

 

centered statistics

See uncentered statistics.

 

centers of action

In meteorology, large semipermanent high- and low-pressure belts distributed around the Earth that largely control the general circulation of the atmosphere. These centers include the Icelandic Low, the Aleutian Low, the Pacific High and the Azores High. See Herman and Goldberg (1985).

 

Central Water

In physical oceanography, a term used to identify thermocline water masses in all three oceans. The water arrives at the thermocline via a process known as subduction. Central Water is characterized by T-S relationships that span a large range that is nonetheless well-defined by the method of formation. The term was originally introduced to differentiate between thermocline water of the central north Atlantic Ocean (now known as NACW) and water from the shelf area to west, but now has the abovementioned broader meaning. See Tomczak and Godfrey (1994).

 

CEO

Abbreviation for Centre for Earth Observation. See the CEO Web site.

 

CEOS

Acronym for Committee on Earth Observation Satellites, a coordinating group of national space agencies and others with interest in satellite data management issues. See the CEOS Web site for further information.

 

CEPEX

Acronym for Central Equatorial Pacific Experiment, conducted in March and April 1993 with the goal of establishing the respective roles of cirrus radiative effects and surface evaporation in limiting maximum surface temperatures in the equatorial Pacific. It examined the validity of a hypothesized thermostat effect which may limit greenhouse warming. Deep intensive convection is observed to occur when tropical SSTs exceed about 27 deg. C. This produces cirrus (ice particle clouds) anvils that spread out over millions of square kilometers. It is hypothesized that while these clouds trap outgoing infrared radiation, they also reduce incoming solar radiation, the net effect being to stabilize SSTs, thereby acting in effect as a thermostat. CEPEX employed surface, airborne, and space-borne platforms to measure radiation fluxes, cirrus radiative and microphysical properties, vertical water vapor distribution, evaporation from the sea surface, and precipitation. See the CEPEX Web site.

 

Ceram Sea

More later.

 

CERES

Acronym for Clouds and the Earth's Radiant Energy System, an EOS experiment that will provide a consistent data base of accurately known fields of radiation and clouds. The CERES experiment will fly broad band, scanning radiometer instruments on polar orbiting and low earth orbit included spacecraft as part of EOS. See the CERES Web site.

 

CERFACS

Acronym for the European Center for Research and Advanced Training in Scientific Computation (Centre Europeen de Recherche et de Formation Avancee en Calcul Scientifique). More information can be found at the CERFACS Web site, including a link to their Global Change division.

 

CESNA

Acronym for the Climate Expert System for the North Atlantic, part of a project to develop a practical system that can manipulate qualitative information in a way that facilitates insights into observed and anticipated climate changes. At present CESNA can be used to estimate changes in mean winter and annual climatic characteristics with a one year lead time in the region that includes eastern North America, the North Atlantic, the adjacent Arctic seas and much of Europe. See the CESNA Web site.

 

CETP

Abbreviation for the Centre d'etude des Environnements Terrestre et Planetaires, a part of the IPSL. See the CETP Web site.

 

CFC

See chlorofluorocarbon.

 

CFL

Abbreviation for Courant, Friedrichs, and Levy, the discoverers of a time step limitation for numerical simulations of partial differential equations.

 

Chrysophyta

A Phylum of phytoplankton that occurs widely in the oceans but is only important in coastal waters. These are motile organisms with one to three unequal flagella, and they possess an elastic cuticle which may either be naked or have lightly silicified or calcified plates. They may be phototrophic, heterotrophic or phagotrophic according to circumstances. Reproduction occurs by fission or budding. Most species contain chlorophyll a with phototrophic species also having chlorophyll c and fucoxanthin.

 

Chukchi Sea

One of the seas found on the Siberian shelf in the Arctic Mediterranean Sea. It is located to the east of the East Siberian Sea, to the north of the Bering Strait, and adjoins the Arctic Ocean proper to the north.

 

CGAM

Abbreviation for Center for Global Atmospheric Modeling, the core group of UGAMP who are responsible for maintaining the UGAMP GCM and related diagnostics for the rest of UGAMP. See the CGAM Web site.

 

CGCP

1. Abbreviation for the Climate and Global Change Program, a NOAA project that addresses key elements of the long-term monitoring and mission-directed research necessary to improve our understanding and prediction of climate variability. See the CGCP Web site. 2. Abbreviation for Canadian Global Change Program.

 

cgs system

A system of units based on the centimeter, the gram and the second as fundamental units. This is usually used in the sciences to express both fundamental and derived units. Compare to mks system.

 

CHAMMP

Acronym for Computer Hardware, Advanced Mathematics, and Model Physics, a DOE program to rapidly advance the science of decade and longer time scale climate prediction. See the CHAMMP Web site.

 

CHAMMPions

A collaborative CHAMMP project between ORNL, ANL and NCAR addressing the use of massively parallel computers for climate modeling. See the CHAMMPions Web site.

 

CHAMP

Acronym for the Coral Health And Monitoring Program, a NOAA project to provide services to help improve and sustain coral reef health throughout the world. The goals include establishing an international network of coral reef researchers to share information about and monitor coral health, providing near real-time data products derived from satellite images and monitoring stations at coral reef areas, providing a data repository for historical data, and adding to the general fund of coral reef knowledge. See the CHAMP Web site.

 

chaos

That which we should be mindful of.

 

Chappuis bands

Spectral bands in which solar radiation is absorbed by ozone in the atmosphere. These are weak absorption bands in the visible and near-IR regions from about 4400 to 11,800 Angstroms. See Liou (1992).

 

Chattian

The second of two ages in the Oligocene epoch (coincidental with the Late Oligocene), lasting from 30.0 to 23.7 Ma. It is preceded by the Rupelian age and followed by the Aquitanian age of the Miocene epoch.

 

chemical actinometry

The measurement of broadband actinic flux by the measurement of the loss of an absorbing gas in a quartz tube or bulb exposed to sunlight. See Jeffries (1995).

 

chemical oceanography

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

 

chemotroph

A species of phytoplankton that can grow without the presence of light. These can be either facultative and also be able to grow in the presence of light or obligate and be completely unable to do so.

 

CHEMRAWN

Acronym for Chemical Research Applied to World Needs.

 

Chile Current

See Peru Current.

 

China Coastal Current

A southward flowing current along the Chinese coast in the Yellow Sea. This current brings low salinity water from the northern parts of the Yellow Sea, particularly the Bohai Gulf, to the south and on into the East China Sea where part of it continues along the coast and another part joins and turns eastward with the northward flowing Taiwan Current.

 

chinook

A warm and dry west wind that occurs on the eastern slope of the Rocky Mountains. It usually arrives suddenly with a consequent large temperature rise and rapid melting of snow.

 

chlorinity

The mass in grams of pure silver necessary to precipitate the halogens in 328.5233 grams of sea water. See Riley and Chester (1971).

 

chlorofluorocarbon

Any of a group of exceptionally stable compounds containing carbon, fluorine, and chlorine, which have been used especially as refrigerants and aerosol propellants. Chlorofluorocarbons, often abbreviated as CFCs, are climatically significant for their ability to break down ozone molecules in the atmosphere. They are also significant as a greenhouse gas since, molecule for molecule, they are 10,000 times more efficient in trapping heat in the atmosphere than carbon dioxide.

 

Chlorophyta

A Phylum of phytoplankton that are green algae ranging from unicellular to macroscopic types. Most species are phototrophic and the marine forms are mainly in the ultraplankton to nanoplankton range. Some reproduce by cell division and others asexually by means of zoospores or autospores. They occur mainly in coastal waters at temperature latitudes in late summer and autumn.

 

chlorosity

The number of grams of chloride and chloride equivalent to the bromide in one liter of sea water at 20 deg. C. See Riley and Chester (1971).

 

CHN

Abbreviation for Carbon-Hydrogen-Nitrogen analyzer.

 

Chronomeric Standard hierarchy

In chronostratigraphy, a system of formally naming intervals of geologic time. This Chronomeric Standard hierarchy consists of the terms eon, era, period, epoch, age and chron. These terms are capitalized when used with the names of the intervals to which they refer, e.g. Cretaceous Period, Campanian Age, etc. This system is used concurrently with the the geochronologic or geologic time unit system called the Stratomeric Standard hierarchy.

 

chronostratigraphy

A branch of stratigraphy dealing with time as a correlative factor among rock sequences. Contrast with lithostratigraphy and biostratigraphy.

 

CHS

Abbreviation for Canadian Hydrographic Service.

 

CIC

See Climate Impact Center.

 

CIDS

Acronym for CEPEX Integrated Data System, a system to provide easy and uniform access to all the observations from CEPEX. See the CIDS Web site.

 

CIESIN

Acronym for Consortium for International Earth Sciences Information Network, a private, nonprofit corporation with members from leading universities and non-government research organizations established in 1989 to further the interdisciplinary study of global environmental change. CIESEN is agency-neutral and specializes in the access and integration of physical, natural, and socionomic information across scientific disciplines. See the CIESIN Web site.

 

CIMSS

Abbreviation for the Cooperative Institute for Meteorological Satellite Studies, located at the SSEC at the University of Wisconsin. See the CIMSS Web site.

 

circle of mean temperature

A concept advanced by Sir James Clark Ross in 1847 in which he posited that there is a latitude circle where the mean temperature of the sea is constant through its entire depth. North of this line, located at 56 deg. S and having a temperature of 39.5 deg. F, the sun warms the sea to temperatures above this mean temperature such that at 45 deg. S the mean temperature line has descended to 600 fathoms. The limit of the sun's influence was ascertained to be 1200 fathoms, at which latitude the surface temperature was 78 deg. F. Similarly, the mean temperature line descends to the south of the circle where it exists at a depth of 750 fathoms at 70 deg. S, above which the temperature decreases to a surface minimum of 30 deg. F. The latitude of the circle corresponds closely to the mean position of what is now known as the Antarctic Convergence, thus leading to Ross identifying an important oceanic feature for the wrong reasons. The figure of 39.5 deg. F was used because Ross, throughout his 3 year voyage, consistently measured temperatures at depths as great as 1200 fathoms but never record a temperature lower than 39.5 deg. F due to pressure distortion effects on his thermometers. See Deacon (1971).

 

CIRES

Acronym for the Cooperative Institute for Research in Environment Science, a joint venture between the University of Colorado at Boulder and the ERL of NOAA. This program is aimed at understanding a variety of basic and applied problems associated with the physics and chemistry of the solid earth and its atmosphere, crysosphere, and oceans. More information can be found at the CIRES Web site.

 

cirrocumulus

A type of cloud composed of ice crystals and shaped in the form of layers. It is formed at an altitude of approximately 26,000 feet.

 

cirrostratus

A type of cloud composed of ice crystals and shaped in the form of heaps or piles. It is formed at an altitude of approximately 27,000-28,000 feet.

 

cirrus

A type of cloud composed of ice crystals and shaped in the form of hairlike filaments. It is formed at an altitude of approximately 29,000 feet.

 

CISK

See conditional instability of the second kind.

 

CITE

Acronym for Chemical Instrumentation Test and Evalutation, a field program of the NASA GTE. The CITE missions focused on the evaluation ofthe ability of airborne instrumentation to measure key tropospheric constituents. The first two, CITE 1 and CITE 2, evaluated instruments for measurements of carbon monoxide (CO), the hydroxyl radical (OH), nitric oxide (NO), nitrogen dioxide (NO2), nitric acid (HNO3), and peroxyacetyl nitrate (PAN), with CITE 2 also including an emphasis on questions related to the abundance and partitioning among the major members of the odd nitrogen family. CITE 3 emphasized the major sulfur species in the troposphere, evaluating instrumentation for measurement of sulfur dioxide (SO2), hydrogen sulfide (H2S), carbon disulfide (CS2), dimethyl sulfide (DMS), and carbonyl sulfide (COS) as well as addressing questions related to the abundance and photochemistry of these species. See Beck and et al. (1987) (CITE 1), Hoell and et al. (1990) (CITE 2), and Hoell and et al. (1993) (CITE 3).

 

clade

A group of organisms believed to have evolved from a common ancestor.

 

cladistics

The systematic classification of groups of organisms on the basis of the order of their assumed divergence from ancestral species.

 

cladogram

A method of graphing the evidence of the most probable evolutionary relationships between organisms by delineating the branching sequences in an evolutionary tree. They are statements of general pattern testable by applying more data and are useful for the analysis of biogeographic history. This is one of two types of dendrograms. See Nelson and Platnick (1981).

 

CLAES

Acronym for the Cryogenic Limb Array Etalon Spectrometer, a UARS instrument used to measure the concentration of ClONO2 in the atmosphere.

 

clapotis

More later.

 

CLASS

Abbreviation for Canadian Land Surface Scheme, an LSP. See Verseghy (1991) and Verseghy et al. (1993).

 

clastic

Descriptive of a rock or a sediment consisting mainly of broken fragments derived from preexisting rocks or minerals that have been transported a large distance from their place of origin. Aeolianites consist of clastic material. See Sellwood and Price (1994).

 

CLAW hypothesis

See DMS-cloud-climate hypothesis.

 

Clementsian school

One of two major schools of thought in phytosociology in the first half of the twentieth century, the other being the Braun-Blanquet school. This school, based in the USA, identified succession as having the primary role in determining the character of communities. In this view the `association' was the final stable or semi-stable climax community and placed emphasis on the dominants. The climax was assumed to represent the response of plants to the prevailing climatic conditions, and each climatic type would induce an appropropriate climax community. This is known as the monoclimax hypothesis. This school uses a deductive methodology. See McIntosh (1978).

 

CLEOPATRA

Acronym for CLoud Experiment OberPfAffenhofen TRAnsports, an experiment conducted in summer 1992 in Southern Germany. The project goal was to quantify elements of the hydrological cycle on a regional scale in dependence upon precipitation events and the vegetation state. Other goals were to describe the mechanisms that force the organization of deep convective systems, to compare theories and observations of atmospheric depositions, and to test and compare observational methods from platforms on the ground, on aircraft and in space. See Meischner et al. (1993).

 

CLICOM

Acronym for CLImate COMputing which, along with INFOCLIMA, is a WCDMP project to coordinate the implementation, maintenance and upgrading of automated climate data management procedures and systems in WMO member countries. CLICOM is a system for the collection, quality control and archiving of climate data and the production of climate applications products. INFOCLIMA is a system developed to provide information on climate data sets which are available in various services and institutions as well as information about observing station networks and National Climate Centers. See the CLICOM/INFOCLIMA Web site.

 

CLIMAP

Acronym for Climate: Long-Range Investigation Mapping and Prediction, a project started in 1971 by a consortium of scientists from many institutions to study the history of global climate over the past million years, particularly the elements of that history recorded in deep-sea sediments. One goal of CLIMAP, the Last Glacial Maximum Project, was to reconstruct the boundary conditions for the climate 18,000 years ago to serve as boundary conditions for atmospheric GCM simulations. See Project (1976) and Project (1981).

 

climate

Traditionally defined in terms of the mean atmospheric conditions at the earth's surface. Peixoto and Oort (1992) offer the more technical and broader "set of averaged quantities completed with higher moment statistics (such as variances, covariances, correlations, etc.) that characterize the structure and behavior of the atmosphere, hydrosphere, and cryosphere over a period of time." Any definition as least implicitly involves some sort of averaging procedure to distinguish the climate from that more instantaneous quantity we call the weather.

 

climate change

This is defined by the United Nations Convention on Climate Change as ``change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods.'' This definition deliberately introduces the concept of a difference between changes in climate that include the effects of anthropogenic increases in greenhouse gases and changes that would occur otherwise.

Other definitions of climate change are often used, both colloquially and scientifically, and may include natural fluctuations, anthropogenic fluctuations, or both. Distinctions are also sometimes made between local and global climate change or short- and long-term climate change. A careful perusal of the context in which it is used should usually yield the definition if not offered. See Houghton and Filho (1995).

 

climate drift

The divergence of a coupled atmosphere-ocean numerical model simulation from an initial or observed state due to imbalances between the components. See also systematic errors and flux correction. The origin of this drift is the mismatch between the externally-prescribed air-sea surface fluxes used to drive each model during the spin-up phase and the surface fluxes computed by the coupled model once the ocean and atmosphere components are joined. Sources for this difficulty involve shortcomings in the simulation of extensive layers of marine stratocumulus clouds in tropical and sub-tropical regions, errors in surface fluxes, insufficient model resolution, spin up and initialization difficulties, sea ice representation problems, and the treatment of the vertical penetration of heat into the ocean. This has also been called solution drift. See Sausen et al. (1988), Manabe and Stouffer (1988), and Meehl (1992).

 

climate forcing agents

Any of several factors which can change the balance between the energy (in the form of solar radiation) absorbed by the Earth and that emitted by it in the form of long-wave infrared radiation, i.e. the radiative forcing of climate. Examples include changes in the amount or seasonal distribution of solar radiation that reaches the Earth due to Milankovitch forcing, changes in the albedo due to desertification, deforestation, or changes in ice area, and the absorption of solar radiation by aerosols in the atmosphere.

 

Climate Impact Center

A research center located at Macquarie University in Sydney, Australia whose mission is to study the impacts of climatic variability and climatic change on Australia and its neighboring countries in the Asia-Pacific region. See the CIC Web site.

 

climate-physiology-vegetation model

A climate-vegetation model with an additional level of complication. The physiological responses of individual species of plants are included with the climatic variables to model the process of plant competition and succession to predict the steady-state vegetation expected under given climatic conditions. An example is the LINKAGES model.

 

climate space

In pollen data analysis, this is a space created by plotting pollen data with respect to axes of the warmest and coldest month mean temperatures of the geographical location at which the pollen data was obtained. An isoline drawn on such a graph depicts a surface, the elevation of which at any point in climate space reflects abundance of the pollen taxon. This surface is called the pollen-climate response surface for that taxon with respect to those climate variables.

 

climate-vegetation model

See bioclimatic classification scheme.

 

climatic optimum

A period, lasting from about 5000 to 2000 B.C. when average temperatures are hypothesized to have reached a higher level, probably on a world-wide scale, than in the last million years.

 

climax vegetation

Vegetation which, if left undisturbed, will eventually attain a steady state constrained by prevailing conditions in the environment (climate, soil, animals, relief, parent material).

 

CLIMVIS

Acronym for the Climate Visualization system, an interactive graphing tool designed to allow visual browsing of the data available on-line at the NCDC. See the CLIMVIS Web site.

 

CLIVAR

Acronym for the WCRP's study of Climate Variability and Predictability, scheduled to run from 1995-2010. It focuses on the variability and predictability of the 'slow' climate system, i.e. those physical processes working on seasonal, interannual, decadal, and centennial time scales. CLIVAR is complementary to the GEWEX program. See McPhaden (1995) and the CLIBAR Web site.

 

cloud absorption anomaly

A discrepancy between cloud absorption of solar radiation as inferred from aircraft radiation and that simulated by models. Measurements yield a value for R, the ratio of the short-wavelength cloud radiative forcing (CRF) at the Earth's surface to that at the top of the atmosphere (TOA), of about 1.5, whereas radiative-transfer models produced R values of around 1.0. It is not as yet certain whether this is a real phenomenon or an aberration stemming from uncertainties in either aircraft flux observations or input parameters for radiative-transfer modeling.

 

cloud ceiling

The height above ground to the bottom of a cloud.

 

cloud classification

A system for classifying clouds based on the system proposed by Luke Howard, a London pharmacist, in 1803. Howard divided clouds into three fundamental forms: stratus (sheet or layer clouds), cumulus (heaped-up clouds), and cirrus (fibrous or tufty clouds). The form nimbus was also added to indicate a rain cloud, but is now used only in composite forms, e.g. cumulonimbus. The prefix alto- indicates clouds with bases in the middle troposphere, well away from the immediate influence of the ground.

Clouds are also classified into the height-based categories of low (up to 2 km), medium (2 km to 6 km), and high (above 6 km), with examples in each category being, respectively, cirrus, altocumulus, and stratus. The official International Classification scheme assigns a number to nine types of clouds. These are (ranging from high to low altitude types): (0) cirrus, (1) cirrocumulus, (2) cirrostratus, (3) altocumulus, (4) altostratus, (5) nimbostratus, (6) stratocumulus, (7) stratus, (8) cumulus, (9) cumulonimbus.

A pictorial guide to the various cloud types can be found in the University of Illinois Cloud Catalog.

 

cloud forcing

The difference between the radiation budget components for average cloud conditions and cloud-free conditions. Roughly speaking, clouds increase the albedo from 15 to 30%, which results in a reduction of absorbed solar radiation of about 50 W/ . This cooling is offset somewhat by the greenhouse effect of clouds which reduces the OLR by about 30 W/ , so the net cloud forcing of the radiation budget is a loss of about 20 W/ . Were the clouds to be removed with all else remaining the same, the Earth would gain this last amount in net radiation and begin to warm up. See Hartmann (1994).

 

cloud fraction

In the numerical modeling of climate processes, the atmosphere is discretized as a collection of 3-D grid boxes. The average effects of the physical processes occuring throughout each entire box are represented by a calculation at one point at the center of each box. One parameter needed for the calculations is the horizontal extent of clouds in each box that can absorb and reflect solar radiation. In the real world counterpart of each box clouds are usually irregularly distributed throughout the entire box with there being both clear and cloudy areas. A minimal estimate of their collective effective is the cloud fraction, a single number that estimates the percentage of the horizontal area of the box that contains clouds. The clouds also don't all have the same properties, e.g. optical depth, so it is preferable and more accurate to obtain a frequency distribution of the cloud properties in the cloudy regions of the box. See Wielicki et al. (1995).

 

cloud height

A parameter needed in numerical climate models to calculate the vertical extent of clouds in the atmosphere. This enables the number of vertical grid boxes over which physical processes pertaining to clouds must be calculated to be ascertained. See Wielicki et al. (1995).

 

Cloud Liquid Water

The CLW content is defined as the total mass of cloud water in a vertical column of atmosphere per unit of surface area.

 

cloud radiative forcing

The amount by which the presence of clouds alters the top-of-atmosphere energy budget, this is the difference between the cloud-free radiation budget climatology and the average over all possible cloud scenario types. ERBE measurements show the net effect of clouds on the present climate to be a net cooling of 20 W/m2, with a short wave CRF contributing 50 W/m2 cooling (via reflection of incoming short wave radiation) and a long wave CRF contribution of 30 W/m2 warming (the greenhouse effect). See Hartmann (1993) and Wielicki et al. (1995).

 

cloud seeding

Dropping silver iodide crystals or dry ice into selected clouds to simulate ice crystal formation and induce precipitation.

 

CLW

See Cloud Liquid Water.

 

CMDL

Abbreviation for the Climate Monitoring and Diagnostics Laboratory, a NOAA laboratory that conducts research related to atmospheric constituents that are capable of forcing change in the climate of the earth through modification of the atmospheric radiative environment, and those that may cause depletion of the global ozone layer. See the CMDL Web site.