Aa-Am

   

AABW

Abbreviation for 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.

 

AAOE

Abbreviation for Airborne Antarctic Ozone Experiment, a program taking place in late Winter 1987 to acquire the scientific observations needed to understand the Antarctic ozone hole. See the AAOE Web site.

 

AAS

Abbreviation for Atomic Absorption Spectroscopy.

 

AASE

Abbreviation for Airborne Arctic Stratospheric Expedition, a NASA experiment to study the production and loss mechanisms of ozone in the north polar stratospheric environment and to study the effect on ozone distribution of the Arctic polar vortex and of the cold temperatures associated with the formation of polar stratospheric clouds (PSCs). See the AASE Web site.

 

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.

 

AATE

Abbreviation for Arctic Acoustic Transmission Experiment, a project of the APL at the University of Washington School of Oceanography.

 

AATSR

Abbreviation for Advanced Along-Track Scanning Radiometer.

 

ABF

Abbreviation for Angola-Benguela Front.

 

ABL

Abbreviation for atmospheric boundary layer.

 

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.

 

ABLE

Acronym for Arctic Boundary Layer Expeditions (or Experiment).

 

ABP

Abbreviation for Acoustic Backscatter Probes.

 

ABRACOS

Acronym for Anglo-Brazilian Amazonian Climate Observation Study, the objectives of which were to monitor Amazonian climate, improve the understanding of the consequences of deforestation, and to provide data for the calibration and validation of GCMs and GCM sub-models of Amazonian forest and post-deforestation pasture. See Roberts and Cabral (1993) and the ABRACOS Web site.

 

abroholos

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 a unit volume of the sample. It is expressed in grams per cubic meter and also 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.

 

abyssal hill

Small hills found only in the deep sea which rise from the ocean basin floor with heights ranging from 10 to over 500 feet and widths from a few hundred feet to a few miles. They are found along the seaward margin of most abyssal plains and originate from the spreading of mid-ocean ridges. As such, they usually form two strips parallel to mid-ocean ridges. They generally decrease in height as one traverses away from the ridges as they gradually become covered with sediment and are replaced by abyssal plains. See Fairbridge (1966).

 

abyssal plain

Flat areas of the ocean basin floor which slope less than 1 part in 1000. These were formed by turbidity currents which covered the preexisting topography. Most abyssal plains are located between the base of the continental rise and the abyssal hills. The remainder are trench abyssal plains that lie in the bottom of deep-sea trenches. This latter type traps all sediment from turbidity currents and prevents abyssal plains from forming further seaward, e.g. much of the Pacific Ocean floor. See Fairbridge (1966).

 

abyssal zone

This originally meant (before the mid-1800s) the entire depth area beyond the reach of fisherman, but later investigations led to its use being restricted to the deepest regions with a uniform fauna and low temperatures. Thus it was distinguished from the overlying bathyal or archibenthal zone with more varied fauna and higher temperatures. Eventually an underlying hadal zone was defined for areas in trenches and deeps below 6000-7000 m depth. The upper boundary of the abyssal zone ranges between 1000-3000 m, with the position of the 4 C isotherm generally considered the demarcation line. It is the world's largest ecological unit, with depths exceeding 2000 m comprising over three-quarters of the world ocean. See Fairbridge (1966).

 

abyssopelagic zone

One of five vertical ecological zones into which the deep sea is sometimes divided. There is a pronounced drop in the number of species and the quantity of animals as one passes into this zone. It is separated from the overlying bathypelagic zone by the 4 C isotherm and from the underlying hadopelagic zone at about 6000 meters. The distinction between pelagic and benthic species can be difficult to ascertain in this zone. See Bruun (1957).

 

ACATS

Acronym for Airborne Chromatograph for Atmospheric Trace Species, an instrument used for the measurement of several species important in the chemistry related to stratospheric ozone depletion such as N O, sulfur hexafluoride (SF ), and a wide range of chlorinated hydrocarbons including the CFCs. This was built as a collaborative effort between the NOAA ERL Aeronomy Laboratory (AL) and Climate Monitoring and Diagnostics Laboratory (CMDL) programs. ACATS is both an ongoing project and a series of instruments for that project. See the ACATS Web site.

 

ACC

1. Abbreviation for the Antarctic Circumpolar Current. 2. Abbreviation for the Alaskan Coastal Current.

 

ACCE

Abbreviation for Atlantic Climate Change Experiment, an experiment planned to study the role of the Atlantic thermohaline circulation in global atmospheric climate. It will take place largely in the North Atlantic region, including the equatorial basin where drifters will be employed. See the ACCE Web site.

 

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 NOAA 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

1. Abbreviation for Antarctic Current Experiment, a GARP project. 2. 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 perturbations of the background aerosols. See the ACE Web site. 3. Abbreviation for Advanced Composition Explorer, a NASA satellite.

 

acid rain

The deposition on land and water of strong acids (H SO , HNO ) in the form of rain, snow, fog, cloud water, and dry deposition. These acids are formed by the oxidation of SO and NO emitted to the atmosphere during the combustion of fossil fuels. See Bricker and Rice (1993).

 

ACME

Abbreviation for Advisory Committee on the Marine Environment, an ICES committee.

 

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.

 

ACMP

Abbreviation for Advisory Committee on Marine Pollution, an ICES committee.

 

ACMRR

Abbreviation for Advisory Committee of Experts on Marine Resources Research, a FAO committee.

 

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.

 

ACOH

Abbreviation for Advisory Committee for Operational Hydrology, a WMO committee.

 

ACOMR

Abbreviation for Advisory Committee on Oceanic Meteorological Research, an WMO committee.

 

ACOPS

Abbreviation for Advisory Committee on Protection of the Sea.

 

acoustic signature

A set of characteristics used to describe a sound signal. This may include sound echos from targets, radiated and ambient noise, with salient echo characteristics including target strength, spectral reflectivity versus frequency, doppler shift, doppler spread and target range extent.

 

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 transmits 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. The ADCP measures the ocean current velocity continuously over the upper 300 m of the water column, usually in 8 m depth increments. It is also used to estimate the abundance and distribution of biological scatterers over the same depth range and in the same depth increments.

ADCP data collection requires that four instruments work together. These are the ADCP itself, the ship's gyrocompass, a GPS receiver, and a GPS Attitude Determination Unit (ADU). See NODC's Shipboard ADCP Center (SAC).

 

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.

 

Adhemar, Joseph Alphonse

A French mathematician who was the first to suggest that the prime causal mechanism of the ice ages might be variations in the way the earth moves around the sun. He published this suggestion in a book entitled Revolutions of the Sea in 1842. He reasoned that the precession of the equinoxes, presently causing the southern hemisphere to have more hours of darkness per year than daylight, was what caused and maintained the ice sheet on Antarctica. He then theorized that the cycle of the precession of the equinoxes would cause whatever hemisphere was having the longer winter to have an ice age.

It is now well known that the centering of the large Antarctic land mass over the South Pole shields any ice or snow that forms there from the moderating effects of the ocean and, combined with the process of ice-albedo feedback, keeps the continent cold enough to form an ice sheet. It is also now known that the total amount of heat received by a hemisphere during the year is the same for both. Although Adhemar was wrong about the details, he did correctly identify orbital variations as a possible cause of ice ages, prompting others to follow him with better and more complete theories of the effects of orbital variations on the climate of the earth. See Imbrie and Imbrie (1979).

 

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.

 

ADIOS

Acronym for Asian Dust Input to the Oceanic System.

 

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 C and a salinity of 38.6, a density greater than that of the overlying LIW. See Buljan and Zore-Armanda (1976) and Tomczak and Godfrey (1994).

 

ADVANCE-10K

Acronym for Analysis of Dendrochronological Variability and Natural Climates in Eurasia: The Last 10,000 Years, an EU project in which the absolute dating control and seasonal growth of long tree-ring chronologies will be used to reconstruct a range of climate variables in different regions of northern Eurasia to enhance knowledge of natural climate variability on a range of timescales within the last 10,000 years and to advance understanding of the mechanisms and forcings that generated this variability. See the ADVANCE-10K Web site.

 

ADVICE

Acronym for Annual to Decadal Variability in Climate in Europe, a project whose goals are: (1) to characterize as fully as possible the variability of climate over greater Europe, including Iceland, the Near East, and parts of North Africa, over the last 215 years; and (2) to reconstruct the climate during the Late Maunder Minimum (from 1675-1715). See the ADVICE Web site.

 

AEDD

Abbreviation for Arctic Environmental Data Directory, a repository for information on the Arctic in support of the Arctic Research and Policy Act of 1984. It contains descriptions of data on global change studies, environmental interactions, earth sciences, social sciences, and policy and management. See the AEDD Web site.

 

Aegean Deep Water

See POEM Group (1992).

 

Aegean Sea

A marginal sea in the eastern Mediterranean Sea centered at approximately 25 E and 38 N. It is located between the Greek coast to the west, the Turkish coast to the east, and the islands of Crete and Rhodes to the south. It contains more than 2000 islands forming small basins and narrow passages with very irregular coastline and topography. It covers an area of 20,105 km , has a volume of 74,000 km , and a maximum depth of 2500 m.

It is connected to the Levantine Sea to the southeast via the Cassos Strait (67 km wide, 350 km deep) between Crete and Karpathos, the Karpathos strait (43 km wide, 550 m deep) between Karpathos and Rhodes, and a 17 km wide and 350 m deep strait between Rhodes and Turkey. It joins the Ionian Sea and Cretan Sea to the southwest through three wide passages between Crete and Antikithira (32 km wide, 700 m deep), Antikithira and Kithira (33 km wide, 160 m deep), and Kithira and Peloponnese (11 km wide and 180 m deep). There is considerable and complicated interchange of water with the eastern Mediterranean through these passages. The Dardanelles provide a northern link to the Black Sea from which the Aegean receives around 190 km per year of water.

The surface circulation is most affected by the prevailing northerly, cold and dry winds (called Etesians and the low salinity (from 26.2 in the summer to 35 in the winter) inflow from the Black Sea. The winds cause upwelling along the eastern coast, an east-to-west temperature gradient, intense convective movements of surface water, and a southward flow along the Greek coast. There is also evidence for a double gyre circulation in the summer, anticyclonic in the east and cyclonic in the west, and an overall cyclonic circulation in the winter with a northerly current along the Asia minor coast and a southerly current along Greece. The surface flow in the south has been found to be into the Aegean between Kithira and Crete, Crete and Karpathos, Karpathos and Rhodes, and Rhodes and Turkey, and into the Mediterranean between Kithira and the Peloponnese coast.

The warm and saline intermediate waters originate in the Chios Basin and feature a strong pycnocline that inhibits vertical mixing. Deep water inflow from the Mediterranean between 500-800 m between Antikithira and Crete and between Crete and Karpathos is suggested by low salinity waters there. The region around Rhodes is a source of Levantine Intermediate Water (LIW), and the densest water found in the Mediterranean has been measured in the Mount-Athos Basin. See POEM Group (1992).

 

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).

 

Aeronomy Laboratory (AL)

A part of the ERL component of NOAA that conducts research on chemical and physical processes of the earth's atmosphere to advance the capability to observe, predict, and protect the quality of the atmosphere. See the AL Web site.

 

AEPS

Abbreviation for Arctic Environmental Protection Strategy, a program adopted by the governments of the eight circumpolar nations at the First Arctic Ministerial Conference in Rovanierni, Finland in June 1991. The objectives of the AEPS are to protect the Arctic ecosystems; provide for the protection, enhancement, and restoration of natural resources; recognize and seek to accomodate the traditional and cultural needs of the indigenous peoples; regularly review the state of the Arctic environment; and identify, reduce, and, finally, to eliminate pollution. The programs established to meet these objectives include AMAP, PAME, EPPR, CAFE, and SDU. See the AEPS Web site.

 

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.

 

AEROCE

Acronym for Atmosphere/Ocean Chemistry Experiment.

 

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.

 

AESOP

Acronym for Airborne Experiment to Study Ozone Photochemistry, an airborne chemistry study performed during the summer of 1994 by the Tropospheric Chemistry group of the NOAA ERL Aeronomy Laboratory (AL). The NOAA Orion P-3, a midsize aircraft capable of measuring through the planetary boundary layer (PBL) and the lower and middle free troposphere, flew over the Denver and Nashville metropolitan areas to make measurements needed to understand the processes and sources of the ozone precursors that shape the distribution of ozone. The compounds and quantities measured were O , NO, NO , PAN, NOy, NO/O , CO, SO and aerosols (with the latter measured using the ASSP and FSSP instruments).

 

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).

 

AFZ

Abbreviation for Arctic Frontal Zone.

 

AGAGE

See ALE/GAGE/AGAGE.

 

AGASP

Acronym for Arctic Gas and Aerosol Sampling Program.

 

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.

 

AGCM

Abbreviation for atmospheric general circulation model.

 

AGDW

Abbreviation for Aegean Deep Water.

 

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.''

 

age of tide

The delay, usually a day or two, between full and new moons (when the equilibrium semi-diurnal tide is maximum) and the following spring tides. This terminology was first used to refer to this phenomenon by Whewell in 1883, although Defant referred to it as ``spring retardation'' in 1961 and Wood later (in 1978) used the terms ``age of the phase inequality'' and ``age of the diurnal equality'' to refer to, respectively, the ages of the semi-diurnal and diurnal tides. This delay is caused by frictional energy dissipation in coastal seas, although a localized increase in the age of tide is also a good indication of resonances at that location. See Murty and El-Sabh (1985).

 

agger

See double tide.

 

AGGG

Abbreviation for Advisory Group on Greenhouse Gases, a WCP committee.

 

agnatha

An animal in the superclass Agnath.

 

Agnath

A superclass of the subphylum Vertebrata of the phylum Chordata. This has replaced the former class Cyclostomata and includes primitive, jawless vertebrates. Examples are lampreys, hagfish and many fossil forms. This class is also known as Marsipobranchii.

 

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

Abbreviation for American Geophysical Union.

 

aguaje

A condition observed annually in the coast water off Peru in which the water is discolored red or yellow and there is a significant loss of marine life. It typically occurs from April through June and is probably caused by an increase in water temperatures via the importation of warmer waters by ocean currents. This causes the death of temperature sensitive marine organisms such as dinoflagellates, which may in turn kill other organisms via the release of toxins. The annual nature of this phenomenon makes it distinct from the El Nino phenomenon occurring in the same region. This is also known as salgaso or aqua enferma.

 

Agulas Basin

An ocean basin located off the southern tip of Africa at about 43 S in the South Atlantic Ocean. It includes the Agulhas Abyssal Plain. See Fairbridge (1966).

 

Agulhas Current

The branch of the western boundary current in the Indian Ocean south of 30 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 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. See Lutjeharms and van Ballegooyen (1988) and Peterson and Stramma (1991).

 

Agulhas Retroflection

See Peterson and Stramma (1991).

 

Agulhas Return Current

See Peterson and Stramma (1991).

 

AIDJEX

Acronym for Arctic Ice Dynamics Joint Experiment, a program that took place in two phases in 1975-1976. In summer 1975 four manned camps were maintained on ice floes in the Arctic Ocean to measure surface and geostrophic winds, ocean current velocities, and ice floe position. In April of 1976 the submarine USS Gurnard traversed 777 nautical miles along three tracklines in the Beaufort Sea, collecting ice thickness data from upward-looking acoustical soundings. See the AIDJEX Web site.

 

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.

 

Air Resources Laboratory (ARL)

A part of the NOAA ERL network that performs studies related to climate and air quality with research focused on turbulence and diffusion in the atmosphere, global transport of pollutants, meteorology of air pollution, air-surface exchange, and global climate change. See the ARL Web site.

 

AIRES

Acronym for Automatic Recording Inverted Echo Sounder.

 

AIRMoN

Acronym for Atmospheric Integrated Research Monitoring Network, an array of stations designed to detect the benefits of emissions controls mandated by the Clean Air Act Amendments of 1990 and to quantify these benefits in terms of deposition to sensitive areas. This is a program of the Air Resources Laboratory of NOAA. See the AIRMoN Web site.

 

AIRS

Acronym for Atmospheric Infrared Sounder or Advanced 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

A theory of waves of small amplitude in water of arbitrary depth that is also known as linear wave theory. The derivation of the theory, given the assumptions of small wave slope ( ) and a depth much greater than the wave height ( ), gives the expression for the water surface elevation

where H is the wave height, k the wave number, and the wave frequency. An expression for the wave length has also been developed, although it must be solved iteratively.

Simpler expressions are available for the limiting cases of deep and shallow water, with deep water being the case where (where h is the depth and the deep water wavelength) and shallow water the case where . The particles move generally in closed elliptical orbits that decrease in diameter with depth, reducing to limiting cases of circles and straight lines in, respectively, deep and shallow water. See Kinsman (1984), LeMehaute (1976) and Komar (1976).

 

AIS

1. Abbreviation for Airborne Imaging Spectrometer. 2. Abbreviation for Advanced Ionospheric Sounder.

 

Aitken counter

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

 

AITMP

Abbreviation for Arctic Ice Thickness Monitoring Project.

 

AIW

Abbreviation for Arctic Intermediate Water.

 

AIWEX

Acronym for Arctic Internal Wave Experiment, a project of the APL at the University of Washington that took place in 1985. See also LEADEX.

 

Ajax Expedition

An oceanographic research expedition from 1983-1984.

 

AL

Abbreviation for Aeronomy Laboratory.

 

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).

 

ALADIN

Acronym for Atmospheric Laser Doppler Instrument.

 

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

A narrow, high-speed, westward flow which extends for more than 1000 km along the coast of Alaska. This is a separate feature from the offshore, deepwater Alaskan Stream. It was not recognized as such up until the mid-1970s when a series of hydrocast surveys in the area was begun which led to its identification as a distinct circulation feature. The ACC is driven by freshwater discharge from the mountainous and coastal regions around the Gulf of Alaska and the consequent nearshore confinement of this low-salinity water by westward winds. It is typically narrow (< 50 km), shallow (< 150 m) and partially baroclinic. It flows most intensely between 145 and 155 W through the Shelikov Strait between the Alaskan Peninsula and Kodiak and Afognak Islands, but extends recognizably along the Peninsula as far as 165 W.

The baroclinic speeds and transports have been estimated as typically <30 cm s and 0.4 Sv, respectively, in the winter, spring and summer. In the fall, when the freshwater influx leads to the spin-up of the ACC, the speeds and transports have been estimated as 89-133 cm s and 1.0-1.2 Sv, respectively. Current mooring measurements have yielded estimates of six-month mean total transports ranging from 0.85 Sv at 151 W to 0.64 Sv at 155 in Shelikof Strait, with daily means as high as 2.5 Sv and marked variability from day to day. This variability is thought to be mainly due to variations in wind-forcing caused by the passage of large-scale storms along the coast. The mean baroclinic transport as estimated from the same measurements was found to be about 75% of the total. See Stabeno et al. (1995).

 

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 W. It abuts the Balearic Sea to the east. See Fairbridge (1966).

 

ALE

Acronym for Arbitrary Lagrangian Eulerian.

 

ALE/GAGE/AGAGE

Abbreviation for Atmospheric Lifetime Experiment/Global Atmospheric Gases Experiment/Advanced GAGE. This is a program in which continuous high frequency gas chromatographic measurements of two biogenic/anthropogenic gases (methane and nitrous oxide) and five anthropogenic gases (chlorofluorocarbons (3 types), methyl chloroform, carbon tetrachloride) are carried out at globally distributed sites. The program began in 1978 and is divided into three parts associated with changes in instrumentation: (1) the ALE part which used HP5840 gas chromatographs; (2) the GAGE part which used HP5880 gas chromatographs; and (3) the AGAGE part which uses a full automated system containing a custom-designed sample module and HP5890 and Carle Instruments gas chromatographic components. The ALE/GAGE/AGAGE data are available via CDIAC.

 

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 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).

 

ALEX

Acronym for AIDJEX Lead Experiment, which took place Feb. 23 through Apr. 10, 1974 and investigated small-scale meteorological and oceanographic processes associated with leads in pack ice near Barrow, Alaska. The experiment plan called for rapid deployment of five instrumental huts, measuring equipment and personnel by helicopeters and fixed-wing aircraft. The processes of primary interest were sensible, latent, and radiant heat loss to the atmosphere as well as the sinking of convective plumes of saline water formed by freezing and brine rejection at the surface. Logistical problems limited the success of the experiment, with the helicopter range limiting deployment to within 30 miles of Barrow and a dearth of suitable leads in that area. See ().

 

ALFOS

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

 

Alfred Wegener Institute (AWI)

The German national research center for polar and marine research. The Institute was founded in 1980 and named after the geophysicist and polar researcher Alfred Wegener. The mandate of the AWI includes fundamental scientific research in the polar regions, national coordination of polar research projects, and logistic support of polar expeditions from other German institutes. The Institute uses the RV Polarstern to perform research at sea. See the AWI Web site.

 

ALFS

Acronym for Alaska Landscape Flux Study.

 

algae

The common name for a division of primitive marine plants in which the body shows little or no differerentation of the vegetative organs, i.e. no true root, stem, or leaf. Algae also have no true vascular system. This category includes seaweeds as well as unicellular and filamentous organisms. The study of algae is known as either algology or phycology.

 

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 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 Arnone et al. (1990) and Tomczak and Godfrey (1994).

 

algology

The study of algae. This is also known as phycology.

 

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.

 

ALIPOR

Acronym for Autonomous Lander Instrumentation Packages for Oceanographic Research, a project funded by MAST III to create a European fleet of lander vehicles that can operate together in joint research projects. Lander vehicles will be built to carry out a variety of experiments ranging from sediment probes to fish tracking. Three facets of lander technology are to be addressed: (1) the development of techniques to launch a fleet of landers from a single ship; (2) the development of new sensors for examining processes in the water of the deep benthic boundary layer at depths ranging from 200 to 5000 meters; and (3) the design and construction of two new types of landers, i.e. one that can carry several sensing devices and another compact one that can be operated from a small vessel. See the ALIPOR Web site.

 

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).

 

ALOMAR

Acronym for Arctic Lidar Observatory for Middle Atmospheric Research.

 

ALPEX

Acronym for Alpine Experiment.

 

ALPTRAC

Acronym for High Alpine Aerosol and Snow Chemistry Study, a EUROTRAC project to study the deposition of acidity and aerosols in the ecologically sensitive high Alpine regions. The objectives were to determine the main physical and chemical processes responsible for the occurrence and accumulation of acidic and aerosol components in the high alpine region and to investigate the contribution of various source regions to the deposition of trace components and their geographical and seasonal trends. This project was finished at the end of 1995. See the ALPTRAC Web site.

 

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.

 

ALVIN

A deep submersible commissioned on June 5, 1964 at the Woods Hole Oceanographic Institution. It has been used for over a thousand research and rescue missions in the years since it was first launched, most from aboard the tender ship Atlantis II, which was retired from that duty in 1996. See the ALVIN Web site.

 

AMAHSE

Acronym for Amazonas Heat Source Experiment.

 

AMAP

Acronym for Arctic Monitoring and Assessment Program, an international organization established to implement certain components of the Arctic Environmental Protection Strategy (AEPS) adopted by governments of the eight circumpolar countries and the First Arctic Ministerial Conference in 1991. The objectives of AMAP are to measure the levels and assess the effects of anthropogenic pollutants in all compartments of the Arctic environment. See the AMAP Web site.

 

AmasSeds

Abbreviation for Amazone Shelf Sediment Study.

 

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 (AGU)

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. See the AGU web site.

 

American Meteorological Society (AMS)

An organization founded in 1919 to promote the development and dissemination of information and education on the atmospheric and related oceanic and hydrologic sciences. The journals published by the AMS include ``Journal of the Atmospheric Sciences,'' ``Journal of Applied Meteorology,'' ``Journal of Physical Oceanography,'' ``Monthly Weather Review,'' ``Journal of Atmospheric and Oceanic Technology,'' ``Weather and Forecasting,'' ``Journal of Climate,'' ``Bulletin of the American Meteorological Society,'' ``Meteorological and Geoastrophysical Abstracts,'' and the ``AMS Newsletter.'' See the AMS Web site.

 

AMERIEZ

Acronym for Antarctic Marine Ecosystem Research at the Ice Edge Zone. See Smith and Garrison (1990).

 

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.

 

amino-acid dating

See Bradley (1985).

 

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.

 

AMIR

Acronym for Advanced Microwave Imaging Radiometer.

 

AMODE-MST

Abbreviation for Acoustic Mid-Ocean Dynamics Experiment-Moving Ship Tomography group. See AMODE-MST Group (1994).

 

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.

 

AMP

Abbreviation for Advanced Microstructure Profiler, an instrument developed at the APL.

 

amphidrome

A stationary point around which tides rotate in a counterclockwise (clockwise) sense in the northern (southern) hemisphere, i.e. the point about which the cotidal lines radiate. The vertical range of the tide increases with distance away from the amphidrome, with the amphidrome itself the spot where the tide vanishes to zero (or almost zero). This is also called an amphidromic point. See Fairbridge (1966).

 

amphridomic point

See amphidrome.

 

Amphineura

A class of the Phylum Mollusca of marine invertebrates. These are commonly known as chitons and are flat, benthic animals which creep along the ocean bottom using a broad, flat foot. All 630 or so known species are marine.

 

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.

 

AMRS

Abbreviation for Alliance for Marine Remote Sensing, an international nonprofit association founded in 1990 which develops and promotes marine applications of remote sensing technologies. It owns and operates the Center for Marine Remote Sensing located in Bedford, Nova Scotia and publishes a newsletter called ``backscatter.'' See the AMRS Web site.

 

AMS

1. Abbreviation for American Meteorological Society. 2. 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, a Japanese project. 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 W.

 

Amundsen Sea

A marginal sea of Antarctica centered at about 112 W and 73 S. It sits between the Bellingshausen Sea to the east and the Ross Sea to the west, with the Antarctic Circle serving as the northern boundary. See Fairbridge (1966).

 

AMUSE

Acronym for A Mediterranean Undercurrent Seeding Experiment.