Tn-Tz

 

TOA

In climate modeling, an abbreviation for top of atmosphere.

 

TOGA

Acronym for Tropical Ocean and Global Atmosphere program, a WCRP program. See the TOGA Web site.

 

TOMS

Acronym for Total Ozone Mapping Spectrometer, an instrument for measuring stratospheric ozone levels that flew on the Nimbus 7 satellite until it ceased operation in May 1993 and is also on the Russian Meteor-3 spacecraft launched in August 1991. A TOMS instrument will also fly on the ADEOS mission. See Krueger (1983) and the TOMS Web site.

 

TOPEX/Poseidon

A cooperative project between the U.S. and France to develop and operate an advanced satellite system dedicated to observing the Earth's oceans. It uses radar altimetry to measure sea surface height over 90% of the world's ice-free oceans. It circles the world every 112 minutes and will gather data to 3 to 5 years. It has a 10-day repeat orbit and flies between latitudes 65 deg. N and S. When combined with a precise determination of the spacecraft orbit, the altimetry will yield global maps of ocean topography from which the speed and directions of ocean currents worldwide will be calculated. The TOPEX/POSEIDON orbit was carefully designed to avoid aliasing the solar tides into undesirable frequencies as happens with sun-synchronous spacecraft, which allows it to serve as a global tide gauge. Other features that contribute to the precise and accurate alimetry of this instrument include a higher orbit than other spacecraft, the inclusion of a water vapor radiometer designed to collect correction information, an ionosphere insensitive altimeter, and more accurate tracking than for other missions. See the TOPEX/Poseidon Web site.

 

topographic form stress

The integrated horizontal pressure force on the bottom. See McWilliams (1996).

 

topographic Rossby wave

To be completed. See Hendershott (1981), p. 309.

 

topographic steering

The deflection or steering of flow required to keep the potential vorticity constant. For large scale processes in the interior of the ocean, we can neglect the relative vorticity and the potential vorticity reduces to f/D. As such, if a water column stretches, i.e. D increases, (shrinks, i.e. D decreases) to accomodate a greater (lesser) depth, then it must move toward (away from) the nearest pole to increase (decrease) f to keep its ratio to D constant.

 

TOPSAR

Acronym for Topographic Synthetic Aperture Radar, an aircraft radar interferometer that uses a synthetic aperture radar and interferometry to rapidly produce topographic maps of the Earth. See the AIRSAR/TOPSAR Web page.

 

TOPSAT

Acronym for topographic satellite, a planned mission to use two nearly identical satellites in tandem to acquire a global topographic map of the Earth. The satellites would use an L-band (25 cm wavelength) radar system. The first year in orbit would be used to produce the global topographic and succeeding years for long-term global hazard detection, e.g. monitoring volcanoes, mud flows, floods, and droughts. See the TOPSAT Web site.

 

torr

A unit of pressure equal to 1 mm mercury under standard density and standard gravity.

 

Tortonian

The fifth of six ages in the Miocene epoch (the first of two in the Late Miocene), lasting from 11.2 to 6.5 Ma. It is preceded by the Serravallian age and followed by the Messinian age.

 

total ozone

A quantity used to describe the horizontal distribution of ozone. It is given by

where is the density of the ozone and the concentration. Total ozone is expressed in Dobson units (DU), which represent in thousandths of a centimeter the depth the ozone column would have at standard temperature and pressure. See Salby (1992).

 

TOU

Abbreviation for True Oxygen Utilization. See AOU.

 

TOVS

Acronym for TIROS Operational Vertical Soundings (or Operational Vertical Sounder), an instrument that flew on the TIROS-N and NOAA-N satellites series. TOVS is a actually a complex of instruments that comprises HIRS, MSU, and SSU. TOVS data are used for the derivation of atmospheric soundings, vertical profiles of temperature and humidity on a global basis, and to correct AVHRR data for atmospheric attentuation during the retrieval of sea surface temperature observations.

 

TPOP

Abbreviation for the TOGA Program on Prediction. See the TPOP Web site for more information.

 

TPW

Abbreviation for true polar wander. See polar wander.

 

TRACER

Acronym for Tropospheric Radiometer for Atmospheric Chemistry and Environmental Research.

 

trade winds

The trade winds, or tropical easterlies, are the winds which diverge from the subtropical high-pressure belts, centered at 3-40 deg. N and S, towards to equator, from north to east in the northern hemisphere and south to east in the southern hemisphere.

 

Traditional Stratigraphic Scale

A name proposed by Harland (1978) for the older geologic time scale being gradually superseded by the SSS.

 

TRAMAR

Acronym for Tropical Rain Mapping Radar.

 

tramontana

A name given to a northerly wind in the Mediterranean. It is usually dry and cold.

 

transfer efficiency

In marine ecology, the ratio of the production of one trophic level to that of the next. This is a reasonable estimate of the ecological efficiency if it is assumed that the energy extracted from a given trophic level is proportional to its production. See Barnes and Hughes (1988).

 

transfer function

A device used in paleoclimate data analysis to obtain proxy data. An equation, or transfer function, is developed using mathematical techniques of regression that relates the actual data (.e.g. planktonic fossil assemblages) to some desired physical variable (.e.g. water temperature). See Imbrie and Kipp (1971), Kipp (1976) and Crowley and North (1991).

 

transfer velocity

See piston velocity.

 

transitive

In dynamical systems theory, a system is said to be transitive if different sets of initial conditions all evolve to a single resultant state. Compare to intransitive and almost intransitive. See Lorenz (1979).

 

transmittance

In radiation transfer, the fraction of incoming radiation that is transmitted into or through a medium. The sum of this, the absorptance, and the reflectance must equal unity.

 

TRANSPAC

Acronym for TRANS-PACific experiment.

 

transpiration

The process by which the liquid water contained in soil is extracted by plant roots, passed upwards through the plant, and discharged as water vapor to the atmosphere.

 

trap effect

A decrease in albedo due to multiple reflections created by undulations of the underlying surface and elements of vegetative cover. See Kagan (1995).

 

TRE

Abbreviation for Tracer Release Experiment.

 

tree line

A term used to signify, on the hemispherical scale, the latitudinal limit of tree growth, and on the regional scale, the higher altitude limit of tree growth within a region.

 

tree ring analysis

More later.

 

TREM

Acronym for Tropical Rainfall Experimental Mission.

 

Triassic

The first period of the Mesozoic era, lasting from 245 to 208 Ma. It precedes the Jurassic period and follows the Permian period of the Paleozoic era, and is comprised of the Early (245-240 Ma), Middle (240-230) and Late (230-208 Ma) epochs. It is named for the three-fold division of the period which can be made at the type locality in Germany.

 

tritium

A hydrogen isotope useful as a tracer in ocean studies. It is the heaviest isotope of hydrogen, and emits a low energy beta particle in its decay to helium-3. Being hydrogen, it exists almost exclusively as water and is thus transported only by fluid motion and vapor exchange, making it an ideal hydrologic tracer. Tritium is produced naturally in the upper atmosphere by cosmic ray spallation, with pre-nuclear concentrations in precipitation around 5-10 Tritium Units (TU) and surface water concentrations ranging from 0.1 to 0.5 TU. The pre-nuclear natural inventory was around 3.6 kg.

Atmospheric nuclear weapons testing in the 1950s and 1960s produced tritium in quantities that dwarfed the natural inventory which, given the subsequent cessation of such testing, offered a unique opportunity to study the long-term transport through the ocean of a large spike of an important and readily identified tracer. About 500 kg of tritium was produced by the weapons testing programs, boosting the concentration in precipitation to as high as 10,000 TU in places, with surface seawater concentrations reaching 20-30 TU in the northern hemisphere. The latitudinal distribution of weapons tritium delivery to the ocean is characterized by mid-latitude maxima (near 45-50 deg.) with about a five-fold asymmetry between northern and southern hemisphere. The time history of surface delivery is a spike for the northern hemisphere and more extended for the southern hemisphere.

The usefulness of tritium as a tracer is due to its time history not monotonically increasing (i.e. the weapons source is no more) which gives independent time information, the strong hemispheric asymmetry in its delivery which is valuable in the study of cross-equatorial flow and, finally, its nature as an ideal fluid tracer since, being part of the water molecule, it is unaffected by biological and chemical processes. The long-term evolution of its large-scale distribution will provide much useful information about ocean circulation processes. See Sarmiento (1988) and Broecker and Peng (1982).

 

Tritium Unit

A unit defined as 10**18 times the atom ratio of tritium to normal hydrogen.

 

TRMM

Abbreviation for the Tropical Rainfall Measuring Mission project, a joint program with Japan which will make extensive measurements of precipitation in tropical regions, the heat engine for global climate, which cannot be time-sampled adequately from polar orbit. See the TRMM Web site and Simpson et al. (1988).

 

Troll and Paffen scheme

A bioclimatic classification scheme based (uniquely) on considerations of seasonality, which recognizes five primary bioclimatic zones. These are the polar/subpolar, cold-temperate/boreal, cool-temperate, warm-temperature subtropical, and tropical zones, each of which are subdivided into further categories based on various seasonality criteria. See Troll and Paffen (1964) and Muller (1982).

 

trophic level

In marine ecology, a single level or layer in the transfer of food or energy in a chain. There can be several levels, with distinct size gradations between levels. Organisms that obtain their food by the same number of steps from plants are said to belong to the same trophic level.

 

tropical SST paradox

This refers to an apparent contradiction between tropical SSTs as inferred from various proxy data and as calculated by the present generation of computer models for past warm periods. The measurements for the Pliocene, Eocene and Cenomanian suggest that tropical SSTs were not significantly greater than those at present, while model simulations for these times show significant differences. See Crowley and North (1991).

 

tropical year

The interval between two successive passages of the Sun in its apparent motion through the First Point of Aries. This is the interval between two similar equinoxes or solstices and the period of the seasons. Its length is 365.242194 mean solar days.

 

tropopause

The atmospheric vertical boundary between the troposphere below and the stratosphere above.

 

troposphere

The narrowest of the atmospheric layers, extending from the surface of the Earth to about 10 km at the Equator and 6 km at the poles near the 200 mbar level. This layer contains about 85% of the atmosphere's total mass and almost all of the water vapor. Temperatures fall with height at the rate of about 0.5 deg. F per 100 feet. It is bounded above by the tropopause which varies with latitude and season.

 

truncation error

That which occurs when a function, theoretically represented exactly as the summation of an infinite (or otherwise bloody huge) number of terms, is represented by a smaller subset of these terms. The difference between the exact function and the function represented by the finite number of terms is called the truncation error. This is one of several kinds of errors inherent in representing a continuous world discretely on computers.

 

T-S diagram

A graph showing the relationship between temperature and salinity as observed together at, for example, various depths in a water column. In the ocean certain T-S combinations are preferred which leads to the procedure of identification via the definition of water types and water masses and their distributions.

 

TSS

See Traditional Stratigraphic Scale.

 

Tsugara Current

A current flowing east from the Japan Sea through the strait between mainland Japan and Hokkaido and on into the Pacific Ocean. There it turns south at around 42 deg. N, gradually merges with the Oyashio Current, and finally becomes part of the Northern Pacific Polar Front. The Tsugara is a continuation of the northerward flowing Tsushima Current. See Tomczak and Godfrey (1994).

 

tsunami

A Japanese word meaning ``harbor wave''. This is often used (along with the even more incorrect ``tidal wave'') as a name for what is more correctly called a seismic sea wave. A true harbor wave is a type of seiche.

 

Tsushima Current

A branch of the Kuroshio Current that flows into the Japan Sea via the Korea Strait. This brings in warm water which is ultimately exported to the Pacific via a continuation of the Tsushima called the Tsugara Current. The Tsushima splits into two branches near 35 deg. N when it encounters the Tsushima Islands, with the western branch following the Korea coast and eventually turning east to join the Polar Front and the eastern branch closely following the Japanese coast until it becomes the Tsugara Current. The transport varies seasonally, with August transport about 1.3 Sv (at up to 4 m/s) and January transport only 0.2 Sv (below 0.1 m/s). Most of the increased August transport passes through the western branch as the eastern branch is weak year round. Both branches are prone to major pathway shifts and the western branch tends to shed large eddies where it separates from the Korean coast. The western branch has also been called the East Korea Current. See Tomczak and Godfrey (1994).

 

TTAPS

An acronym used to refer to the authors of the original paper detailing the nuclear winter scenario. It was also used as shorthand to refer to the scenario itself.

 

TTO

Abbreviation for Transient Tracers in the Ocean.

 

turbidity current

Moree later.

 

turbulence

Much, much bloody more later.

 

turnover time

A time scale defined as the ratio of the mass of a reservoir to the rate of its removal from that reservoir. In the context of the climate this can be seen as the total amount of carbon dioxide in the atmosphere and its rate of removal via land and ocean processes.

 

Turonian

The second of six ages in the Late Cretaceous epoch, lasting from 91.0 to 88.5 Ma. It is preceded by the Cenomanian age and followed by the Coniacian age.

 

Type A response

In paleoecology, a change in the local abundance of vegetation species. See Webb (1986).

 

Type B response

In paleoecology, a change in the geographic distributions of vegetation species. See Webb (1986).