Aa-Am

   

AABW

See Antarctic Bottom Water.

   

AACW

Abbreviation for Antarctic Circumpolar Water.

 

AAE

Abbreviation for annual actual evapotranspiration, a variable used in the Thornthwaite scheme for bioclimate classification. The AAE depends on the monthly values for potential evapotranspiration, precipitation and soil moisture storage as detailed in Thornthwaite (1948).

 

AAIW

Abbreviation for Antarctic Intermediate Water.

 

AASP

Abbreviation for the American Association of Stratigraphic Palynologists, founded in 1967 to promote the science of palynology. See the AASP Web site.

 

AASW

Abbreviation for Antarctic Surface Water.

 

AATSR

Abbreviation for Advanced Along-Track Scanning Radiometer.

 

ABF

Abbreviation for Angola-Benguela Front.

 

ABL

Abbreviation for atmospheric boundary layer, one of the two types of PBL.

 

ablation

The removal of mass from a glacier by the processes of surface melting, evaporation, and iceberg calving.

 

ablation zone

One of five glacier zones used to categorize areas on glaciers in terms of ice temperature and melting. The ablation zone is the area below the equilibrium line below which there is a net loss of ice over the year. The superimposed ice zone exists above this line.

 

abroholos

The name given to violent squalls on the coast of Brazil that prevail from May to August.

 

absolute humidity

The ratio of the mass of water vapor in a sample of moist air to the volume of the sample. It is expressed in grams per cubic meter and also sometimes called the vapor concentration.

 

absolute vorticity

The sum of the relative vorticity ( ) and the planetary vorticity, i.e. .

 

absorptance

In radiation transfer, the fraction of incoming radiation that is absorbed by a medium. The sum of this, the transmittance, and the reflectance must equal unity.

 

absorption

A process by which incident radiation is taken into a body and retained without reflection or transmission. It increases either the internal or the kinetic energy of the molecules or atoms composing the absorbing medium.

 

absorption band

In atmospheric radiative transfer, a collection of absorption lines in a particular frequency interval.

 

absorption line

In atmospheric radiative transfer, a discrete frequency at which an energy transition of an atmospheric gas occurs due to the absorption of incident solar radiation. The line width depends on broadening processes, the most important of which are natural, pressure (also known as collision), and Doppler broadening.

 

ABT

In bioclimatology, an abbreviation for annual biotemperature, a variable used in the Holdridge system. It is defined as the annual mean of monthly mean temperatures, where the monthly means are those above .

 

ABW

See Arctic Bottom Water.

 

ACC

Abbreviation for the Antarctic Circumpolar Current.

 

ACCE

Abbreviation for Atlantic Climate Change Experiment.

 

acceleration

1. In physics, this means one thing. 2. In heterochrony, this is a type of peramorphosis that occurs as an increase in the degree of allometry. For meristic characters it is an increase in the rate of production of structures.

 

ACCLAIM

Acronym for the Antarctic Circumpolar Current Levels by Altimetry and Island Measurements program in the South Atlantic and Southern Oceans. It consists of measurements from coastal tide gauges and bottom pressure stations, along with an ongoing research program in satellite altimetry. See the ACCLAIM Web site.

 

ACCP

Abbreviation for the Atlantic Climate Change Program, a research initiative for understanding the decadal-scale interactions of deep circulation in the Atlantic and how it influences the overlying atmosphere. See the ACCP Web site.

 

accumulation mode

One of three categories used to summarize the distribution of atmospheric aerosols in terms of production mechanism and particle size, the others being the nucleation and coarse particle modes. The accumulation mode ranges in size from 0.1 to 1 m in diameter and its production mechanism is by coagulation and heterogeneous condensation. See Jaenicke (1993b).

 

accuracy

The degree of freedom from error. The total error compared to a theoretically true value. Contrast with and see precision for an example.

 

ACE

Abbreviation for Aerosol Characterization Experiments, a part of the IGAC program. ACE-1 is the first of a series of experiments that will quantify the chemical and physical processes controlling the evolution and properties of the atmospheric aerosols relevant to radiative forcing and climate. The ultimate objective of these studies is to provide the data necessary to incorporate aerosols into global climate models and reduce the overall uncertainty in the calculation of climate forcing due to aerosols. ACE-1 will document the chemical, physical and radiative properties and determine the controlling processes of the aerosols in the remote marine atmosphere, while ACE-2 will extend these characterization and process studies to the North Atlantic with an emphasis on the anthropogenic perturbatino of the background aerosols. See the ACE Web site.

 

acid rain

The deposition on land and water of strong acids (H2SO4, HNO3) in the form of rain, snow, fog, cloud water, and dry deposition. These acids are formed by the oxidation of SO2 and NOX emitted to the atmosphere during the combustion of fossil fuels. See Bricker and Rice (1993).

 

acme biozone

In biostratigraphy, a type of biozone that relies for definition on the recognition of a maximum occurrence of a fossil that might otherwise range both higher and lower in the succession. See Briggs and Crowther (1990), pp. 466-467.

 

ACMSU

Abbreviation for the Atmospheric Chemistry Modeling Support Unit, a part of UGAMP located at the Center for Atmospheric Science at Cambridge, U.K. The ACMSU is responsible for provision of the chemical data and codes to the rest of UGAMP. See the UGAMP Web site.

 

acoustic tomography

The inference of the state of the ocean from precise measurements of the properties of sound waves passing through it. This technique takes advantage of the facts that the properties of sound in the ocean are functions of temperature, water velocity and other salient oceanographic properties and that the ocean is nearly transparent to low-frequency sound waves. These felicitous circumstances combine to allow signals transmitted over hundreds to thousands of kilometers to be processed with inverse methods to obtain estimates of large-scale fields of ocean properties. An especially advantageous feature of this method is that, given the 3000 knot speed of sound in the ocean, reasonably synoptic fields can be constructed. The chief problems presently encountered in this field are those related to engineering sufficiently accurate transmitters and receivers for the task. See Munk et al. (1995).

 

acoustical oceanography

The study of sound propagation in the ocean and its underlying sediments. This ranges from the earliest use of depth soundings to chart the ocean floor to the use of SONAR to locate schools of fish, underwater vehicles and ocean drifters to the most recent applications of acoustic tomography to infer large-scale properties of the ocean and the ocean floor.

 

ACRIM

Acronym for Active Cavity Radiometer Irradiance Monitor, an experiment that provides long-term, precise measurements of the total amount of the Sun's energy that falls on the Earth's surface, oceans and atmosphere. ACRIM-I flew on the SMM from 1980-1989 and ACRIM II is currently operating on NASA's UARS mission. See the ACRIM Web site.

 

acritarch

An organic-walled and spheroidal microfossil of uncertain taxonomic status. Some consider them to be the cysts of eukaryotic algae. See Bowen (1991).

 

ACRU

Acronym for the Applied Climate Research Unit at the University of Queensland, which performs research into such areas as biometeorology, rainfall prediction, and rural production. See the ACRU Web site.

 

ACSYS

Abbreviation for the Arctic Climate System Study, a WCRP program whose goal to to ascertain the role of the Arctic in global climate. The primary scientific goals are to provide an adequate basis for representation of the Arctic in coupled global models, to develop plans for effectively monitoring the climate in the Arctic, and the determine the role of the Arctic in the sensitivity and variability of global climate. See the ACSYS Web site.

 

actinic flux

Name given to spherical spectral radiant flux density in the atmospheric photochemistry community. It is the photochemically effective flux and the units are photons/cm**2/s/nm over a series of narrow wavelength intervals. No instruments are available to measure this, and it is usually approximated using chemical actinometry techniques. See Jeffries (1995).

 

actual evaporation

The actual amount of water vapor released from a land or water surface, as opposed to potential evaporation.

 

ADCP

Abbreviation for Acoustic Doppler Current Profiler, an instrument used to measure ocean currents. It transmists high frequency acoustic signals which are backscattered from plankton, suspended sediment, and bubbles, all of which are assumed to be traveling with the mean speed of the water. The Doppler shift in the backscatter echo allows the water velocity to be determined. Further processing of the received signals allows a profile of current speed and direction to be determined for the entire water column.

 

ADEOS

Acronym for the Advanced Earth Observing Satellite to be launched by Japan in February 1996. It will be launched into a solar-synchronous sub-recurrent orbit in a recurrent period of 41 days at an altitude of about 800 km. The goal is to collect data appropriate for monitoring environmental changes such as global warming, ozone layer depletion, decrease in tropical rain forests, unusual weather occurences, etc. The instruments ADEOS will carry include AVNIR, ILAS, IMG, NSCAT, OCTS, POLDER, RIS, and TOMS.

 

ADI

Abbreviation for Alternating Direction Implicit.

 

adiabatic

Involving or allowing neither gain nor loss of heat.

 

adiabatic lapse rate

In the atmosphere, the rate of decrease of temperature which occurs when a parcel of air rises adiabatically, i.e. there is no heat transfer to or from the parcel. The adiabatic lapse rate for dry air is -9.8 K/km.

 

adjustment time

A time scale characterizing the decay of an instantaneous input pulse into a reservoir. It is also used to characterize the adjustment of the mass of a reservoir following a change in the source strength.

 

Adriatic Sea

A part of the eastern basin of the Mediterranean Sea located between Italy and the Balkan Peninsula. It is landlocked on the north, east and west, and terminates at the Otranto Strait to the south. This is one of the two regions within the Mediterranean where freshwater input exceeds evaporation (the other being the Black Sea), a a situation caused by outflow from the Po River.

The flow between the Adriatic and the greater Mediterranean through the Otranto Strait is that of a typical dilution basin wherein low salinity water exits near the surface and high salinity water enters at depth. There is an additional outflow layer beneath the incoming Levantine Intermediate Water (LIW) that results from the surface water in the very shallow (less than 200 m) northern Adriatic being greatly cooled by outbreaks of strong and cold winter winds called bora. This gives the deep outflow water, whose characteristics are a temperature of 13 deg. C and a salinity of 38.6, a density greater than that of the overlying LIW. See Tomczak and Godfrey (1994).

 

Aegean Sea

More later.

 

aeolian

Borne, deposited, produced, or eroded by the wind. See Pye (1987), Pye and Tsoar (1990) and Allen (1994).

 

aeolianite

A consolidated sedimentary rock consisting of clastic material deposited by the wind, an example of which is sandstone. See Sellwood and Price (1994).

 

AERI

Acronym for Atmospheric Emitted Radiance Interferometer, a Ground Based High Resolution Interferometer Sounder (GB-HIS) which measures the downwelling atmospheric emitted radiance at 0.5 cm spectral resolution in the spectral range 3-18 um. It measures vertical temperature and water vapor profiles, sea surface temperatures, and cloud optical properties. See the AERI Web site.

 

aeronomy

The study of the atmosphere above about 50 km where dissociation and ionization are prevalent processes.

 

aerosols

These are the non-gaseous microscopic particles and droplets floating in the atmosphere that have a climate forcing effect just as do the greenhouse gases. They come from natural and artificial sources, with the most abundant ones being particles of mineral dust, sulfuric acid, ammonium sulfate, biological material-like pollens, and carbon or soot. Aerosols provide forcing in a couple of ways, the first being providing the nuclei around witch larger drops of water can condense and release latent heat into the atmosphere. They can also absorb or reflect energy radiated from the Sun or Earth. It is not known at present whether their net effect is to heat or cool the Earth.

 

AET

Abbreviation for actual evapotranspiration.

 

AFEAS

Abbreviation for Alternative Fluorocarbon Environmental Acceptability Study.

 

African Waves

A prominent meterological phenomena wherein waves originate over central and western Africa and propagate westward into the eastern Atlantic Ocean. They have wavelengths of around 2500 km, periods of about 3.5 days and move with a westward speed of around 8 m/s. Their genesis begins with strong surface heating over the Sahara during the northern summer combining with cooling of the sea water over the Gulf of Guineau to the south to establish a north-south temperature gradient over central and western Africa. This gradient maintains the mid-tropospheric easterly jet stream because of the associated easterly thermal wind. The upper tropospheric jet easterly jet stream and the southward extension of the mid-latitude westerlies at the upper troposphere sit above this. This combination causes the north-south gradient of the absolute vorticity of the mean zonal wind to change sign in the mid-tropospheric area that contains the African Waves. This sign change is a necessary condition for baroclinic instability which provides a preferable environment for African Wave genesis. See Wiin-Nielsen and Chen (1993).

 

AGCI

1. Abbreviation for Aspen Global Change Institute. 2. Abbreviation for the Atlantic Global Change Institute, established at the BBSR to study global environmental change, its probably consequences and especially the human dimensions of change. See the AGCI Web site.

 

age and area theory

A theory advanced by the British ecologist J. C. Willis to explain how the area occupied by a species is related to its population as a whole. It is simply stated as: statistically speaking, the area occupied by a species is directly proportional to its age as a species, i.e. the longer it has had time to spread, the further it will go. The practical applications of this theory apparently leave something to be desired since, according to Collinson (1988), ``this is an excellent example of a logically satisfying theory which, unfortunately, so rarely fits the facts that it cannot be supported in its original form.''

 

agonic line

A line on a map that joins places where a magnetic compass points true north as well as magnetic north, i.e. a line of zero magnetic declination.

 

AGPI

Abbreviation for the adjusted geosynchronous precipitation index technique for adjusting geosynchronous infrared data to remove known biases. See Adler et al. (1994).

 

AGU

See American Geophysical Union.

 

Agulhas Current

The branch of the western boundary current in the Indian Ocean south of 30 deg. S. This is one of the strongest currents in the world ocean with mean speeds of 1.6 m/s throughout the year and peak speds in excess of 2.5 m/s. It carries 95-135 Sv as it reaches the Agulhas Bank near 35 deg. S. When it encounters the ACC while rounding the Cap of Good Hope, most of its transport turns back into the Indian Ocean in a phenomenon known as the Agulhas retroflection. This is largely due to the current developing instabilities and shedding the eddies that result. More later, eh?

 

air mass

In meteorology, a continguous and widespread body of air that has been stagnant over a surface for a sufficient length of time to have been modifed by the surface. An example would be a maritime air mass that develops with high humidity over an ocean. The formation of air masses is favored in regions of surface high pressure regions due to the ambient light winds allowing the long residence time necessary for modification. Given the prevailing global circulation patterns, warm air mass formation is favored at 30 latitude and cold air mass formation at 90 latitude, with the boundary between these two regions being known as the polar front.

 

AIRS

Acronym for Atmospheric Infrared Sounder.

 

AIRSAR

A side-looking imaging radar system which uses the synthetic aperture principle to obtain high resolution images which represent the radar backscatter of the imaged surface at different frequencies and polarizations. See the AIRSAR/TOPSAR Web page.

 

Airy wave

See Kinsman (1984).

 

Aitken counter

A small expansion chamber used to measure the concentration of CCN in the atmosphere. See Riehl (1954).

 

ALACE

Acronym for Autonomous Lagrangian Circulation Explorer float, an instrument that can be programmed to cycle up and down through the water column at predetermined intervals to provide vertical profiles of temperature and salinity. See Davis et al. (1992).

 

Aland Sea

A part of the Baltic Sea bordered by the Gulf of Bothnia to the north, the Gulf of Finland to the east, and the man part of the Baltic Sea to the south.

 

Alaska Coastal Current

See Alaska Current.

 

Alaska Current

The eastern limb of the counterclockwise-flowing subpolar gyre in the North Pacific. This current is concentrated on the shelf region by the freshwater input from Alaskan rivers which enhances the pressure gradient across it. It is strongest in winter with current speeds around 0.3 m/s and weakest in July and August when prevailing winds tend to oppose its flow. This current may or may not be distinguished from a western boundary current flowing along the Aleutian Islands and called the Alaskan Stream. Both have previously gone by the name of Aleutian Current. Whether or not the nomenclature makes a distinction, the Alaskan Stream and Current do have distinguishing characteristics. The Current is shallow and highly variable while the Stream is steadier and reaches to the ocean floor. The more barotropic nature of the latter is evidence that it is indeed a product of western boundary current dynamics while the former is in an eastern boundary regime. See Tomczak and Godfrey (1994).

 

Alaskan Stream

See Alaska Current.

 

albedo

The proportion of incident radiation reflected by a surface. About 30% of the incoming solar energy is reflected back to space from the earth, of which 25% is reflected by clouds and 5% by the surface or by atmospheric molecules or suspended particles. The clouds and atmospheric gases and particles absorb 25% of the incident radiation with the remainder absorbed at the surface. See Peixoto and Oort (1992), Ch. 6.

 

Albian

The last of six ages in the Early Cretaceous epoch, lasting from 113 to 97.5 Ma. It is preceded by the Aptian age and followed by the Cenomanian age of the Late Cretaceous Epoch.

 

Alboran Sea

A part of the western basin of the Mediterranean Sea that extends from the Gibraltar Strait in the west eastward to the Alboran Islands at about 3 deg. W.

 

ALE

Acronym for Arbitrary Lagrangian Eulerian.

 

ALE/GAGE

Abbreviation for Atmospheric Lifetime Experiment/Global Atmospheric Gases Experiment.

 

Aleutian Current

See Alaska Current.

 

Aleutian low

A center of action centered over the Aleutian Islands between the east coast of the Siberian Kamchatka Peninsula and the Gulf of Alaska at about 50 deg. N. It is prominent in the winter and disappears in summer, with the average central pressure below 1000 mb in January. See Angell and Korshover (1974).

 

ALFOS

Acronym for Long-life, multi-cycle, pop-up RAFOS floats.

 

algae

More later.

 

Algerian Current

A current that flows eastward along the Algerian coast in the Mediterranean Sea. It flows as a narrow, easily distinguished current for around 300 km from about 0 to 4 deg. E with a width of less than 30 km, average and maximum velocities of 0.4 and 0.8 m/s, respectively, and a tranport of about 0.5 Sv. This is a continuation of the current associated with the Almeria-Oran Front that is itself a continuation of the flow of Atlantic Ocean water entering through the Gibraltar Strait. See Tomczak and Godfrey (1994).

 

aliasing

A phenomenon encountered when sampling a continuous function to produce values at discrete points. If the sampling frequency isn't high enough to resolve the highest frequency signal present in the continuous function, then the high frequency information above the sampling frequency will appear as a false enhancement of (or, equivalently, be aliased onto) a related lower frequency in the computed power spectrum.

 

Alk

Common abbreviation for alkalinity.

 

alkalinity

A property of sea water operationally defined as the excess positive charge to be balanced by CO3 and HCO3 ions. The carbonate ion content of any unit of sea water is equal to its alkalinity (i.e. excess positive charge) minus its total dissolved carbon content. See Broecker and Peng (1982).

 

Allen's Rule

An ecogeographical rule, also known as the proportional rule, extends Bergman's Rule to include protruding parts of the body such as necks, legs, tails, ears and bills, i.e. such parts are shorter in animals that dwell in cooler regions. This was established by Joel A. Allen in 1877.

 

Allerod oscillation

A post-LGM European climate regime. This refers to a period of general warmth between 10,000 and 9000 BC. It was preceded by the Bolling oscillation and followed by the Younger Dryas. See Lamb (1985), p. 371.

 

allometry

The relationship between size and shape in an organism or object. In heterochrony, if a particular structure increases in size relative to the whole organism during ontogeny, then the growth is said to show positive allometry; if it decreases in relative size, then it shows negative allometry. Increasing/decreasing the degree of allometry is called peramorphosis/ paedomorphosis.

 

allotropy

The existence of the same state of more than one form of the same element with different properties.

 

alluvial

Of or pertaining to an unconsolidated, stratified deposit laid down by running water. Occasionally applied only to fine sediments (e.g. silt and clay), but more generally referring to coarser sediments such as sand and gravel as well.

 

Almeria-Oran Front

A front and an associated current that separate the fresher water flowing in from the Atlantic Ocean via the Gibraltar Strait from the saltier Mediterranean Sea water to the west. The incoming water flows eastward as a jet, breaks into one or two large eddies of around 150 km diameter, and then is deflected to the right (the south) by the Coriolis force where it encounters the African coast and continues flowing eastward as the Algerian Current. See Tomczak and Godfrey (1994).

 

almost intransitive

In dynamical systems theory, a system is said to be almost intransitive if it mimics transitive behavior for an indeterminate period of time and then switches to an alternative resultant state in the manner of an intransitive system. Thus, different initial conditions may not only lead to different resultant states, but also to eventual transitions between different resultant states. See Lorenz (1979).

 

ALPEX

Acronym for ALPine EXperiment.

 

altocumulus

A type of cloud shaped like heaps or piles and formed at an altitude of approximately 22,000 feet.

 

altostratus

A type of cloud that is grey or bluish striated and either fibrous or a uniform sheet producing light drizzle. It is formed at an altitude of approximately 23,000 to 24,000 thousand feet.

 

Amazon River

More later.

 

AMBIACE

Acronym for the Amazon Biogeochemistry and Atmospheric Chemistry Experiment, a supporting study for LAMBADA that focuses on the consequences fo forest conversion, agriculatural practice and abandonment, and secondary succession on regional and global biogeochemistry and atmospheric chemistry. See the LAMBADA Web site for further information.

 

American Geophysical Union

An international scientific society with over 31,000 members in 117 countries. It is dedicated to advancing the understanding of the Earth and its environment in space and in making the results known to the public. As such it publishes many journals and books and sponsors frequent meetings. More details are available at the AGU web site.

 

AMEX

Abbreviation for Australian Monsoon Experiment, a program of enhanced upper-air soundings and radar data collection in northern Australia aimed at better documentation of those large-scale weather patterns over Australia that are associated with the ebb and flow of the Australian monsoon. See Holland et al. (1986).

 

AMI

Abbreviation for Active Microwave Instrument.

 

AMIP

Acronym for Atmospheric Model Intercomparison Project, a project to compare the numerical results from a standardized simulation performed by over 30 modeling groups. AMIP is being coordinated by the PCMDI on behalf of the WGNE of the WCRP. See Gates (1992) and the AMIP Web site for further details.

 

amount effect

A term applied to the relationship between isotopic composition and monthly rainfall where months with heavy rainfall show different isotopic concentrations than do months with low rainfall. In high rainfall months, rain frequency is higher which entails a higher relative humidity in sub-cloud air, hence less evaporation from raindrops. Since the rate of evaporation determines the isotopic concentrations (the greater the rate the higher the heavy stable isotope composition), low rainfall months should show a higher heavy stable isotopic composition than high rainfall months.

 

amphidrome

A stationary point around which tides rotate in a counterclockwise (clockwise) sense in the northern (southern) hemisphere, with the vertical range of the tide increasing with the distance away from the amphidrome. This is also called an amphidromic point.

 

amphridomic point

See amphidrome.

 

AMPR

Abbreviation for Advanced Microwave Precipitation Radiometer, a total power scanning multifrequency radiometer that collects data at four frequencies while flying aboard the high altitude ER-2 research aircraft. See the AMPR Web site.

 

AMRIR

Acronym for Advanced Medium Resolution Imaging Radiometer.

 

AMRC

Abbreviation for the Antarctic Meteorology Center, a research group supporting the United States Antarctic Program with weather and remote sensing data. See the AMRC Web site.

 

AMS

Abbreviation for Accelerator Mass Spectrometry, a method for measuring long-lived radionuclides that occur naturally in the environment. It uses a particle accelerator in conjunction with ion sources, large magnets, and detectors to separate out interferences and count single atoms in the presence of 1.E15 stable atoms.

 

AMSU

Acronym for Advanced Microwave Sounding Unit.

 

AMTEX

Acronym for the Air Mass Transformation Experiment. See Lenschow et al. (1980).

 

Amundsen Abyssal Plain

One of the three plains that comprise the Pacific-Antarctic Basin (the others being the Bellingshausen and Mornington Abyssal Plains). It is located at around 150 deg. W.

 

Amundsen Sea

More later.

 

AMUSE

Acronym for A Mediterranean Undercurrent Seeding Experiment.