Ba-Bm

 

backing

Said of the anti-clockwise change of direction of a wind, as opposed to veering.

 

BADC

Abbreviation for the British Atmospheric Data Center. See the BADC Web site.

 

Baffin Bay

More later.

 

baguio

The local name given to tropical cyclones in the Phillipines, especially those occurring from July to November.

 

BAHC

Abbreviation for Biospheric Aspects of the Hydrological Cycle, an IGBP program established to study the role of vegetation in the hydrological interactions between the land surfaces and the atmosphere. More information can be found at the BAHC Web site.

 

balance equations

See G. and Flierl (1981), p. 508.

 

Bali Sea

More later.

 

BALTEX

Acronym for the Baltic Sea Experiment, a GEWEX project to study coupled hydrological processes between complicated terrain, sea and ice and the atmospheric circulation to determine the energy and water budgets of the Baltic Sea and related river basins. See the BALTEX Web site for further information.

 

Baltic Current

See Kattegat.

 

Baltic Sea

A dilution basin type of mediterranean sea that is connected to and experiences limited, intermittent water exchange with the North Sea. It comprises several parts separately known as the Gulf of Bothnia, the Aland Sea, the Gulf of Finland, the Gulf of Riga, Kattegat and Skagerrak. It has a mean depth is about 60 m, an area of about 350,000 km2, and a volume of about 20,000 km3.

 

Baltica

A paleogeographic area during the late Precambrian and early Paleozoic that comprised north-western Europe, including most of what are now the U.K., Scandinavia, European Russian and Central Europe. It formed the southeastern margin of the Iapetus Ocean and was moved by the subduction of that ocean (during the Caledonian orogenic event) such that it made contact with North America and Greenland during the Silurian and Early Devonian.

 

Banda Sea

More later.

 

bar

A unit of atmospheric pressure equal to the pressure of 29.530 in. or 750.062 mm of mercury under the standard conditions of 0 deg. C temperature and 9.80665 m/s gravitational acceleration. Also, a popular locale during lengthty conferences.

 

barat

The local name given to strong, northwesterly squalls on the north coast of the island of Celebes that occur most frequently from December to February.

 

Barents Sea

One of the seas found on the Siberian shelf in the Arctic Mediterranean Sea. It is located between the White Sea to the west and the Kara Sea to the east and adjoins the Arctic Ocean proper to the north.

 

baroclinic

Descriptive of an an atmosphere or ocean in which surfaces of pressure and density intersect at some level or levels. The state of the real atmosphere and ocean, as opposed to barotropic. In a baroclinically stratified fluid total potential energy can be converted to kinetic energy.

 

baroclinic flow

In oceanography, the vertically varying circulation associated with horizontal imhomogeneities in the stratification of the oceans.

 

baroclinic instability

To be completed.

 

baroclinic radius of deformation

See Rossby radius of deformation.

 

barotropic

Descriptive of a hypothetical atmosphere or ocean in which surfaces of pressure (isobaric surfaces) and density (isentropic surfaces) coincide at all levels, as compared to baroclinic. In a state of barotropic stratification, no potential energy is available for conversion to kinetic energy.

 

barotropic flow

In oceanography, depth-independent circulation due to changes in surface elevation.

 

barotropic instability

To be completed.

 

barotropic radius of deformation

See Rossby radius of deformation.

 

Barremian

The fourth of six ages in the Early Cretaceous epoch, lasting from 124 to 119 Ma. It is preceded by the Hauterivian age and followed by the Aptian age.

 

barrier reef

One of three geomorophologically distinct types of coral reefs, the other two being fringing reefs and atolls. Barrier reefs are separated from land by a lagoon usually formed by coastal subsidence. See Barnes and Hughes (1988).

 

barrier layer

In physical oceanography, the layer between the thermocline and the halocline, so-called because of its effect on the mixed layer heat budget due to the temperature at the bottom of the barrier layer being zero, which excludes heat loss to the underlying water via mixing. In the Western Pacific, an area with a barrier layer, horizontal temperature gradients are also very small, leading to the conclusion that the net heat flux at the ocean surface must be close to zero. See Tomczak and Godfrey (1994).

 

Bartonian

The third of four ages in the Eocene epoch (the second of two ages in the Middle Eocene), lasting from 43.6 to 40.0 Ma. It is preceded by the Lutetian age and followed by the Priabonian age.

 

barye

The unit of pressure in the c.g.s. system of units, being equal to 1 dyne/cm . Sometimes called a microbar, it is equal to 10 bar.

 

BAS

Abbreviation for British Antarctic Survey.

 

BATERISTA

Acronym for Biosphere-Atmosphere Transfer and Ecological Research In situ STudies in Amazonia, a LAMBADA supporting project focusing on mesoscale/local-scale process studies to provide detailed information to support the formulation and validation of hydroclimatological, biogeochemical and ecological models. See the LAMBADA Web site for further information.

 

bathypelagic

The vertical oceanic zone below around 1000 m where there is no light source other than bioluminescence, temperature is uniformly low, and pressures are great. This is the lowest of the three vertical sections of the pelagic part of the ocean, the other two being the upper euphotic and the middle mesopelagic.

 

BATS

1. Acronym for Bermuda Atlantic Time-series Study, a JGOFS project to obtain and study long-term time-series of biogeochemical cycles in the Sargasso Sea near Bermuda. More information can be found at the BATS Web site. 2. Acronym for Biosphere-Atmosphere Transfer Scheme, an LSP. See Dickinson (1984), Dickinson et al. (1986), Dickinson et al. (1993) and the BATS Web site.

 

Bay of Bengal

The northeastern arm of the Indian Ocean, located between peninsular India and Burma. It covers about 2,200,000 sq. km and is bordered on the north by the Ganges and Brahmaputra River deltas, on the east by the Burmese peninsula and the Andaman and Nicobar Islands, on the west by India proper and Ceylon, and on the south by the Indian Ocean proper. The average depth is around 3000 m with maximum depths reaching over 400 m in the southern parts.

Major circulation features are the East Indian Current, a northward current flowing along the Indian shelf from January through October, and the East Indian Winter Jet, a southwestward flowing current that replaces during the remainder of the year. This current reversal is due to the seasonal change from the Northeast to the Southwest Monsoon and the concomitant wind forcing. General clockwise and conterclockwise circulation gyres are seen throughout the Bay accompanying, respectively, the Current and the Winter Jet, although the situation becomes a bit more complicated during the transition periods.

The monsoonal wind variations and the resulting circulations also serve to induce upwelling near the coasts during the spring (with the northward current) and the piling up of surface water along the coasts during the late fall and early winter (with the southward currents). Thus the isopycnals tilt upwards and downwards towards the shore during, respectively, the spring and late fall. The annual mean SST for the region is above 28.5 deg. C., although upwelling can reduce this to 25-27 deg. C during the spring. The salinities are kept lower than normal oceanic values (especially in the western parts) by extensive monsoonal river runoff. See Tomczak and Godfrey (1994) and Fairbridge (1966).

 

Bay of Bengal Water

A water mass that originates in the northern Bay of Bengal via monsoonal input from the Ganges and Brahmaputra Rivers. It is a low salinity water mass that spreads across the Bay in an approximately 100 m thick layer that produces a strong halocline beneath (above the overlying Indian Central Water) and keeps the surface salinity in the eastern parts of the Bay below 33.0 throughout the year. Although there are no variations in temperature through the BBW layer, there are salinity variations below 50 m (and therefore above the main halocline) due to the fact that weak wind mixing erases variations over only about half the depth of the layer. This causes the permanent existence of a barrier layer. The low salinity surface water to the west of India, sometimes called East Arabian Sea Water (EAW), is usually subsumed under the BBW rubric due to its nearly identical properties. See Tomczak and Godfrey (1994).

 

Bay of Bothnia

See Gulf of Bothnia.

 

BBL

In oceanography, abbreviation for benthic (or bottom) boundary layer.

 

BBSR

Abbreviation for the Bermuda Biological Station for Research, Inc., the mission of which is to conduct research from the special perspective of a mid-ocean island, to educate future scientists, and to provide well-equipped facilities for research. See the BBSR Web site.

 

beam trawl

A sampling device used in biological oceanography to catch bottom-dwelling organisms that live above the sediments. It consists of a rectangular frame (that can be up to 15 m wide and a couple of meters high) that has towing cables hooked to the front and an enclosed net attached to the back. Since this device doesn't dig into the bottom it can be towed fairly rapidly and used to catch faster moving animals like shrimp and fish that live near the bottom. See Sverdrup et al. (1942).

 

Beaufort Sea

More later.

 

Beaufort wind scale

More later.

 

belemnites

Extinct molluscs of class Cephalapod and order Dibranchiata. They were marine invertebrates with the molluscan foot modified into a ring of tentacles around the mouth.

 

Bellingshausen Abyssal Plain

One of three plains that comprise the Pacific-Antarctic Basin (the others being the Amundsen and the Mornington Abyssal Plains. It is located at around 100-120 deg. W.

 

Bellingshausen Sea

More later.

 

Belt Sea

More later.

 

BENE

Acronym for the Biodiversity and Ecosystems Network. See the BENE Web site.

 

BENGAL

Acronym for BENthic biology and Geochemistry of a north-eastern Atlantic abyssal Locality. This is a high resolution temporal and spatial study whose objective is to understand how the properties of the abyssal boundary layer respond to and modify the incoming chemical signal from the surface layers and therefore affect the paleoceanographic record in the underlying sediment. See the BENGAL Web site.

 

Bengal, Bay of

See Bay of Bengal.

 

Benguela Current

More later.

 

benthic

Descriptive of organisms that are attached to or resting on bottom sediments, as opposed to pelagic.

 

benthos

A general term in biological oceanography for organisms and communities found on the seabed. This is usually divided into three categories: meiobenthos, the organisms that pass through a 0.5 mm sieve; macrobenthos, those that are caught by grabs or dredges but retained on the 0.5 m sieve; and epibenthos, those organisms than live on rather than in the seabed. Those in the latter category are usually larger.

 

Bergeron-Findeisen mechanism

A process whereby at temperatures below 0 C the saturation vapor pressure with respect to water is greater than that with respect to ice. Therefore, in a mixed cloud, the air which is close to saturation with respect to water is supersaturated with respect to ice. Consequently, ice crystals will grow much more rapidly than, and at the expense of, water droplets. This is one possible initial stage of precipitation formation.

 

Bergmann's Rule

An ecogeographical rule, also know as the size rule, that states that races of a warm-blooded species of animal are larger in cold climates than in warm climates. It was established by Carl Bergmann in 1847.

 

Bering Sea

A marginal sea located on the northern rim of the Pacific Ocean centered at approximately 58 deg. N and 160 deg. W. It is surrounded by Alaska to the east, Siberia to the west and northwest, and the Aleutian Island arc to the south. It has an area of about 2,300,000 km and a volume of about 3,700,000 km . The bathymetry is about equally divided between a vast shelf to the northeast that is at most 200 m deep and the Aleutian Basin where depths range from 3800-3900 m over most of the region. The Shirshov Ridge (along 171 deg. E between 500-1000 m depth) and the shallower Bowers Ridge (along 180 deg. E then turning west along 55 deg. N) effectively divide the Basin into three parts. It is connected to the Arctic Mediterranean Sea via the Bering Strait and to the Pacific via several sills between the various Aleutian Islands, although the main connection is thought to be between 168 deg. E and 172 deg. W where the sill depth is about 1590 m.

The main circulation features include a large part of the westward flowing Alaskan Stream entering the Bering Sea through the passage centered at 170 deg. W, turning east, and driving a cyclonic (counterclockwise) gyre in the Aleutian Basin. This largely barotropic current sees the two main ridges as obstacles which sets up a system of two eddies, one on each side of the Shirshov Ridge. Eddies have been observed separating from the eastern limb (often called the Bering Slope Current) of the Bering Sea gyre, the larger of the two systems. There is a countercurrent further up the Bering Slope whose dynamics are those of an eastern boundary current in a subpolar gyre. A series of currents and related fronts largely driven by Alaska Stream inflow through a shallower passage at 175 deg. W flow north-northwestward on the broad shelf region.

The main circulation feature of the northern Bering Sea is the Anadyr Current, a largely seasonally invariant current flowing northeastward and supplying most of the Bering Strait throughflow. This throughflow, driven by sea level differences across the strait, varies from about 0.1 m/s in the summer to 0.5 m/s in the winter, with flow through the Shpanberg Strait seasonally shifting from northward to southward to compensate for the differences. The shelf flows also make some mostly unknown contribution to this throughflow. The western limb of the smaller gyre to the west of the Shirshov Ridge contributes to and becomes part of the southwestward flowing Kamchatka Current.

The local water masses are derived from Pacific Ocean water masses transported in to the area and modified by processes on the shelf. This results in a temperature minimum at or below 100 m, low surface salinities rapidly rising to about 300 m, and overall low oxygen concentrations. The water overlying the temperature minimum is surface water imported from the Alaska Stream, and the water below that is Pacific Deep Water. See Tomczak and Godfrey (1994) and Fairbridge (1966).

 

Bering Strait

A narrow ocean passage separating the North American and Asian continents. The transport of water through this passage, estimated at about 0.6 Sv of northward flowing low salinity water largely supplied by the Anadyr Current, contributes little to the global budgets of any ocean properties. Its principal role in large-scale circulation is apparently its contribution to the stratification of the Arctic Ocean. See Aagaard et al. (1985).

 

Bermuda High

See Azores High.

 

Berriasian

The first of six ages in the Early Cretaceous epoch, lasting from 144 to 138 Ma. It is preceded by the Tithonian age of the Late Jurassic epoch and followed by the Valanginian age.

 

BEST

Acronym for Bare Essentials of Surface Transfer, an LSP. See Pitman et al. (1991).

 

beta plane approximation

In oceanography, a simplified coordinate system for the equations of motion where the variation of the Coriolis parameter f with latitude is approximated by

where is the value of f at the mid-latitude of the region and the latitudinal gradient of f at that same latitude. This is used to investigate both equatorial and mid-latitude phenomena (for which there are slightly different beta plane approximations) where f varies significantly over a few tens of degrees latitude. The beta plane approximation allows considerable simplification of the governing equations and therefore the use of analytical investigation methods. This is the next step up in complexity from the f plane approximation. See Gill (1982).

 

beta refraction

An effect that results from the latitudinal variation of Rossby wave phase speed which is, in turn, due to the beta effect. If a line of Rossby waves were started along a straight eastern ocean boundary, then those at low latitudes would arrive at the western boundary before those at high latitudes.

 

beta spiral method

An inverse method for determining the oceanic velocity field where the motion is geostrophic and the potential vorticity locally balanced. See Schott and Stommel (1978).

 

BGMR

Abbreviation for the biomass growth modification ratio, which expresses growth responses at an elevated level of CO2 relative to growth responses at an ambient or control level. See Allen, Jr. (1995).

 

bias

The amount by which the average of a set of values departs from a reference value. In statistics and signal processing, it is usually felicitous to remove this before proceeding to further and more complicated data manipulations.

 

bias correction

A method of flux correction that guarantees no long-term climate drift and reduces the other problems of flux correction. Fluxes are modified at the ocean-atmosphere interface but the correction is carried out on mean annual rather than monthly mean values, thus resulting in smaller and spatially smoother corrections. An interactive computation is also applied to reduce consistencies in the bias correction. This method was developed by J. Oberhuber at the DKRZ.

 

BIBEX

Acronym for Biomass Burning Experiment, an IGAC project. See the BIBEX Web site.

 

Bigelow, Henry Bryant

More later.

 

bioclimatic classification scheme

A method for relating climatic variables to the distribution of vegetation and its characteristics at a global scale. Examples include the Holdridge scheme, the Thornthwaite scheme, the Koeppen scheme, and the Troll and Paffen scheme. See Prentice (1990).

 

biodiversity

The total diversity and variability of living things and of the systems of which they are a part. This includes the total range of variation in and variability among systems and organisms at the bioregional, landscape, ecosystem and habitat levels, at the various organismal levels down to species, populations and individuals, and at the level of the population and genes. It also covers the complex sets of structural and functional relationships within and between these different levels of organization, including human action, and their origins and evolution in space and time. The biological disciplines comprising biodiversity include evolutionary biology, taxonomy (and the related biosystematics), ecology, genetics and population biology. See Heywood (1995).

 

Biogenetic Law

A relationship between ontogeny and phylogeny formalized by E. Haeckel as ``ontogeny recapitulates phylogeny''. This has the phylogenetic meaning that ancestral adult forms are encapsulated in the juvenile stages of their descendants. This is also known simply as ``recapitulation''. See also paedomorphosis.

 

biogenic

One of three major components of deep sea sediments, the other two being authigenic and detrital. Biogenic sediment consists mainly of calcite and opal produced as the hard parts of organisms and eventually precipitated. Calcite is formed by coccoliths (plants) and foraminifera (animals) and opal by diatoms (plants) and radiolarians (animals). See Broecker and Peng (1982).

 

biogeography

The science dealing with the geographical distribution of living organisms.

 

biointermediate

One of three categories into which the regularly cycled chemical constituents of sea salt can be divided in regards to their effects on plant growth, the other two being biolimiting and biounlimited. Biointermediate elements are those which are partially depleted in the surface waters of the ocean. Included in this category are the elements calcium, strontium, nickel, copper, selenium, carbon, barium and radium. See Broecker and Peng (1982).

 

biolimiting

One of three categories into which the regularly cycled chemical constituents of sea salt can be divided in regards to their effects on plant growth, the other two being biointermediate and biounlimited. Biolimiting elements are those which are almost totally depleted in the surface waters of the ocean and therefore limit the growth of plant life. Plant (and animal) activity in the surface waters serve to almost completely remove these constituents, which are replenished when enriched deep waters return to the surface via upwelling. Included in this category are nitrate, phosphate, silicate, zinc, cadmium, and germanium. See Broecker and Peng (1982).

 

biological oceanography

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

 

biological pump

The transformation, via photosynthesis in the ocean surface layer by plant cells (primarily phytoplankton), of dissolved inorganic carbon into biogenic carbon, including for example the CaCO3 in shells of coccolithophorids. This is an oceanic sink for atmospheric CO2 where a rain of small debris consisting of phytoplankton shells and zooplankton fecal pellets and molts sink out of the ocean surface waters. These sinking particles remove POC from surface mixed layers into stratified, relatively deep layers where, on a millenial time scale, it is no longer susceptible to exchange with the atmosphere. Particulate matter removed in this manner is called export flux. See Rowe and Baldauf (1995).

 

bioluminescence

The emission of light by living marine organisms.

 

biome

A community of animals and plants occupying a climatically uniform area on a continental scale.

 

biometeorology

More later.

 

biosystematics

The scientific study of the kinds and diversity of organisms and of any and all relationships among them. This includes the narrower field of taxonomy as well as elements of related biological disciplines like evolution, phylogeny, population genetics and biogeography. See Heywood (1995).

 

Biowatt

A program to study bioluminescence adn optical variability in the sea. See Marra and Hartwig (1984).

 

binomial distribution

The distribution of the number of successes in n trials when the probability of a success remains constant from trial to trial and the trials are independent.

 

binomial nomenclature

In systematics, system of nomenclature established since the time of Linnaeous where each animal has a dual name consisting of genus and species, the most obvious example of which is Homo sapiens.

 

biosphere

The domain of life on Earth. It is an envelope 21 miles thick, extending to 14 miles above sea level and a depth of slightly more than 7 miles at the bottom of oceanic trenches. It comprises the terrestrial vegetation, the continental fauna, and the flora and fauna of the oceans.

 

biostratigraphy

A branch of stratigraphy dealing with fossil plants and animals as a correlative factor among rock sequences, i.e. the use of fossils in stratigraphic correlation. The fundamental unit is the formation. Contrast with chronostratigraphy and lithostratigraphy.

 

biota

All the animals and plants living in an area or region.

 

BIOTAS

Abbreviation for Biological Investigations of Terrestrial Antarctic Systems, an international subgroup of SCAR. See the SCAR Web page for further information.

 

biotemperature

A term used in the Holdridge scheme for describing potential vegetation as a function of temperature and precipitation. The biotemperature is the annual sum of degree days between 0 and 30 deg. C.

 

biotic crisis

A time when the extinction rate greatly exceeds the speciation rate; a mass extinction.

 

bioturbation

The stirring of sediment by animal life.

 

biounlimited

One of three categories into which the regularly cycled constituents of sea salt can be divided in regards to their effects on plant growth, the other two being biolimiting and biointermediate. Biounlimited constituents are those which show no measurable depletion in the surface waters of the ocean, and it is operationally classified as such if its ratio to total salt in both surface and deep water samples are equal within measurement error. They include sodium, potassium, rubidium, cesium, magnesium, boron, sulfur, fluorine, chlorine, bromine and uranium. More accurate analysis techniques could possibly remove some constituents from this category. See Broecker and Peng (1982).

 

biozone

In biostratigraphy, a belt of strata characterized by an assemblage of fossils, of which one abundant and characteristic form is chosen as an index. This is a general term as there are several kinds of biozones recognized, e.g. assemblage, acme, total-range, local-range, concurrent-range and consecutive-range biozones. See Briggs and Crowther (1990), pp. 466-467.

 

bise

A cold, dry wind that blows in the winter in the mountainous regions of southern France from the north, northeast or northwest. A variation of this that occurs in Languedoc (near the Mediterranean coast), the ``bise noir'', is distinguished from the mistral in that it is accompanied by heavy clouds.

 

Bismarck Sea

More later.

 

Bjerknes, Vilhelm

More later.

 

Bjerknes hypothesis

The hypothesis that ENSO varies as a self-sustained cycle in which anomalies of SST in the Pacific cause the trade winds to strengthen or slacken, and that this in turn drives the changes in ocean circulation that produce anomalous SST. First advanced by Bjerknes (1969).

 

Bjerknes' theorem

A generalization of Stokes' theorem that enables the calculation of the circulation on a rotating Earth. See Turner (1973), Hide (1978), and Dutton (1986).

 

black body

More later.

 

Black Sea

A mediterranean sea, centered at approximately 35 deg. E and 44 deg. N, that is the world's largest inland water basin. It has an area of about 461,000 km and a volume of 537,000 km with a mean depth of around 1200 m, although depths greater than 2000 m are common in the central basin. The western part of the Black Sea is a wide shelf that gradually narrows to the south and breaks at around 100-150 m. In the rest of the basin the shelf doesn't exceed 10-15 km in width. It is connected to the Marmara Sea via the narrow (760 m wide) and shallow (27.5 m maximum depth) Bosporus Strait, and further connects to the Mediterranean Sea via the long and narrow Dardanelles. It is also connected to the Sea of Azov to the north.

The Black Sea is a dilution basin due to a large freshwater input from the Danube, Dniester, Dnieper, Severskiy Donets and Don rivers (350 km /yr). The flow through the Bosporus comprises a surface flow of low salinity water towards the Mediterranean (260 km /yr) and an underlying return flow of salty Mediterranean water (120 km /yr). Precipitation (140 km /yr) and evaporation (350 km /yr) close the freshwater budget. The surface salinity in the central part ranges from 16-18, increasing to 21-22.5 at depths greater than 150-200 m. The surface temperatures range from 25 deg. C in the summer to 6-8 deg. C in the open sea, with the northwestern part and the Sea of Azov covered with ice during the winter. The deep water is 8-9 deg. C year round. The upper 50 m are saturated with oxygen, the content of which diminishes until, at a depth of 150-200 m, hydrogen sulfide appears and renders the lower regions uninhabitable.

The circulation in the entire water column consists of counterclockwise motion along the continental slope along with three counterclockwise gyres of similar size filling the western, central and eastern basins. Typical velocities range from 0.1-0.3 m/s. The westernmost gyre serves to bring colder shelf water into the deeper open sea where it sinks and spreads to form a temperature minimum usually observed at 75 m. See Tomczak and Godfrey (1994) and Fairbridge (1966).

 

Black Stream

See Kuroshio Current.

 

BLC

Abbreviation for Belfort Laser Ceilometer, an instrument used in the ARM program for cloud observations. It is a self-contained, ground-based, optical, active remote sensing instrument with the ability to detect and process such cloud-related parameters as cloud height, extinction coefficients, cloud layers and time/date reference information. It detects clouds by transmitting pulses of infrared light vertically into the atmosphere which a receiver telescope detects as scattered light from clouds and precipitation. See the BLC Web site.

 

blending height

A specified height where the information calculated by SVAT models is matched to the overlying GCM grid squares. This is the height at which appropriate fluxes are exchanged. See Houghton and Filho (1995).

 

blocking

A phenomenon, most often associated with stationary high pressure systems in the mid-latitudes of the northern hemisphere, which produces periods of abnormal weather. The normal eastward movement of depressions, troughs, anticyclones and ridges is stalled for periods ranging from a few days to as long as over a month.

 

BMRC

Abbreviation for Bureau of Meteorology Research Center.