- Tahiti Shuttle Experiment
- See Hawaii-Tahiti Shuttle Experiment.
- Acronym for Taiwan Area Mesoscale Experiment. The planning
phase of this took place from 1985-86 and the field operations
phase during 1987.
- Acronym for Tropical Atmosphere Ocean array, a TOGA
experiment, an array of approximately 70 moorings in the tropical Pacific
Ocean that telemeter oceanographic and meteorological data to shore
in real-time via the Argos satellite system.
The development of TAO was motivated by the 1982-1983
El Nino event, the strongest of the century up
to that time.
It was neither predicted nor detected until it nearly reached its peak,
prompting the need for real-time data from the tropical Pacific for monitoring,
prediction, and improved understanding of El Nino.
PMEL began the development of the ATLAS
mooring in 1983 with support from the NOAA EPOCS program.
Prototype ATLAS moorings were field tested in early 1984, with a modest
array deployed along 110W in late 1984.
Additional ATLAS deployments were made beginning in 1985 at the start of
the 10-year TOGA program.
The array, now named TAO, grew slowly during the first half of TOGA,
and then rapidly during the second half as the ATLAS moorings proved a
The full array was not completed until the final month of TOGA (Dec. 1994).
During the 10 years TAO was under development, over 400 buoys were
deployed on 83 cruises using 17 ships from 6 countries.
After TOGA ended, TAO continued under the sponsorship of
CLIVAR, GOOS and
NOAA was comissioned to service the array east of 165E in 1996, and
in 1997 the U.S. Congress authorized long term sustained support of
the array as part of an operational ENSO observing system.
On Jan. 1, 2000, it was officially renamed the TAO/TRITON array,
with sites west of 165E occupied by TRITON
buoys maintained by Japan's JAMSTEC.
The current operationally supported measurements of the array
consist of winds, SST, relative humidity, air temperature,
and subsurface temperature at 10 depths in the upper 500 m.
Five moorings along the equator also measure water velocity.
Additional moorings or enhancements to existing moorings are
occasionally added in support of specific research objectives.
See Hayes et al. (1990) and McPhaden (1995).
- Acronym for Transport Processes in the Atmosphere and the
Oceans, a program to study transport processes in geophysical
fluids mainly from a theoretical point of view.
TAO Web site.
- The new name of the TAO mooring array as
of Jan. 1, 2000.
- Acronym for Transarctic Acoustic Propagation experiment, carried
out in April 1994 at an ice camp north of Svalbard. A joint
US/Russian scientific party deployed an experimental 20 MHz
source and transmitted various signals to listening stations
in the Beaufort and Lincoln Seas for 5 days. TAP was a feasibility
test to see if acoustic signals could be used to study the
Arctic and monitor it on a long term basis.
See Pawlowicz et al. (1995) and the
TAP Web site.
- Acronym for Tracor Acoustic Profiling System, a family of instruments
developed by TRACOR to study the size and extent of populations of
very small marine life by measuring the acoustic signals backscattered
from them at frequencies in the MHz range.
The TAPS sensors can be lowered through the water column in cast mode,
attached to net systems such as the
MOCNESS, or deployed on a
- Abbreviation for Tropical Atlantic Study, a part of the
- Acronym for Trans-Atlantic Study of Calanas finmarchicus, an
EU-funded program to understand the
physical and biological processes which control the population
dynamics of the copepod Calanus finmarchicus, a key
zooplankton species in the northeast Atlantic. A key goal is to
establish the relationship between the physical and biological
factors affecting annual recruitment and reproduction of
the species as a step towards predicting the consequences of
future climate change.
TASC Web site.
- Tasman Front
- See Stanton (1981).
- Tasman Sea
- A marginal sea located in the southwest Pacific centered at about
160 E and 37 S off the southwest coast of Australia.
It is also surrounded by New Zealand to the east, Tasmania to
the southwest, and the
Coral Sea to the north.
The maximum depth is 5943 m.
The bathymetry is essentially composed of the east Australian
Basin in the westerly part and the depression of New Caledonia
to the east, with the two separated by the Lord Howe Sill.
See Rotschi and Lemasson (1967).
- Tatarskyi Strait
- See Okhotsk Sea.
- Taylor column
- If relative motion is created in a rotating container by heating
or by stirring and if an obstacle is placed on the bottom of the
tank so that the moving fluid must flow around it, then the
streamlines of the flow will form a column, going around the
obstacle as if it extended to the top of the water. This is
called a Taylor column. The same sort of phenomena can occur
in real world analogues of this experimental example. This
is a consequence of what is known as the
See Dutton (1986).
- Taylor-Proudman theorem
- A two-dimensional fluid flow theorem that states that geostrophic
motion of a homogeneous fluid will be the same in all planes
perpendicular to the axis of rotation.
This has also been known as the Proudman-Taylor, Proudman or
See Hide (1978).
- Abbreviation for TOGA
COARE International Project Office.
- The ability of a phenomenon in one part of the world to
influence phenomena in another part of the world.
Examples include the influence of the
ENSO phenomena on the
Indian monsoon and the
droughts in the Sahel region of Africa.
Teleconnection pataterns are recurring and persistent large-scale
patterns of pressure and circulation anomalies spanning vast geographical
They are also referred to as preferred modes of low-frequency or long
The patterns typically last for weeks to several months, although they
can occasionally be prominent for several years and thus influence
both the interannual and interdecadacal atmospheric and oceanic
Teleconnection patterns are a naturally occurring part of the chaotic
atmosphere, and arise primarily from internal atmospheric dynamics,
although some are forced by changes in tropical SSTs and convection
associated with the ENSO cycle and the Madden-Julian Oscillation.
The patterns reflect large-scale changes in the wave and jet stream
patterns in the atmosphere, and influence temperature, rainfall,
storm tracks and jet stream location and intensity over large areas.
For example, they can be responsible for abnormal weather patterns
occurring simultaneously at widely separated locations.
A technique called Rotated Principle Coordinate Analysis (RPCA) has
been used to determine the most prominent teleconnection patterns in
the northern hemisphere extratropics. They are:
See Barnston and Livezey (1987) and
Trenberth et al. (1998).
- North Atlantic Oscillation (NAO);
- East Atlantic Pattern (EA), appears in aall months except May-August
and consists of a north-south dipole of anomaly centers spanning the
entire North Atlantic from east to west;
- East Atlantic Jet (Ea-Jet), appears between April and August and
consists of a north-south dipole of anomaly centers, one over the high
latitudes of the eastern North Atlantic and Scandinavia and the other
over Northern Africa and the Mediterranean Sea;
- East Atlantic/Western Russia pattern (EA/WR) (also known as
the Eurasia-2 pattern), prominent in all months except June-August,
with two anomaly centers (over the Caspian Sea and western Europe) in
winter, and three in the spring and fall;
- Scandinavia pattern (SCA) (also known as the Eurasia-1 pattern), seen
in all months except June and July, with a primary center over Scandinavia
and larage parts of the Arctic north of Siberia and two weaker centers
with opposite sign over western Europe and Mongolia/western China;
- Polar/Eurasia pattern (POL), the most prominent mode from December
through February, consisting of one center over the polar region and
centers of opposite sign over Europe and northeastern China;
- Asian Summer pattern (ASU), prominent from June to August, this is
a monopole pattern with anomalies of the same sign throughout southern
Asia and northeastern Africa;
- West Pacific pattern (WP), prominent in all months, consisting of
a north-south dipole during winter and spring, with a third prominent center
appearing in the summer and fall;
- East Pacific pattern (EP), prominent in all months except August and
September, consisting of a north-south dipole of height anomalies over
the eastern North Pacific;
- North Pacific pattern (NP), prominent from March through July, consisting
of a primary center spanning the central latitudes of the western and
central Pacific and a weaker region of opposite sign spanning eastern
Sibera, Alaska and the western mountains of North America;
- Pacific/North American pattern (PNA);
- Tropical/Northern Hemisphere pattern (TNH), prominent from November
to February, consisting of a primary center over the Gulf of Alaska and
a separate center of opposite sign over Hudson Bay; and
- Pacific Transition pattern (PT), prominent between May and August,
consisting of a wave-like pattern of height anomalies extending from
the Gulf of Alaska eastward to the Labrador Sea along 40 deg. N.
- temperature inversion
- In meteorology, a region of negative
- temperature lapse rate
- The rate of decrease of temperature with height.
- temperature ramp
- A coherent structure found in the upper ocean that has been observed
in both stable and unstable conditions.
These are found in the upper few meters, are aligned with the wind, and
marked by horizontal temperature changes of 0.1 K over 0.1 m. They
indicate the upward transport of cool/warm fluid during stable/unstable
conditions, and are driven by an instability triggered by the wind
thought to be similar to the
These are as yet not well understood.
- Abbreviation for Transparent Exopolymer Particles, an organic
ocean particle that is not normally detectable because it is transparent.
These gel-like polysaccharide particles form the matrix of
marine snow and play an important role
in the coagulation of some algal blooms.
See Alldredge and Jackson (1995).
- Acronym for Tropical Eastern Pacific Process Study cruise,
a 1997 PACS study whose purpose was to document the clouds and
precipitation of the tropical eastern Pacific from the surface.
The timing and location of the cruise were designed to permit the
ship's instruments to sample storm structure when and where there
is the greatest difference between the different satellite precipitation
The scientific objectives were:
- to estimate precipitation with radar and compare it with the two
satellite estimates; and
- to understand the physical reasons behind the difference in precipitation
estimates based on infrared and microwave satellite data.
- Tethys Sea
- A paleogeographic term for a sea that
partly intersected Pangaea in the
Permian and later
separated the two
Mesozoic supercontinents of
Laurasia and Gondwana.
- Acronym for Transport of Equatorial Waters, a research project.
- Texas Current
- See Vastano et al. (1995).
- Acronym for TOGA Heat Exchange Program.
- thermal diffusivity
- A number that characterizes the rate of molecular diffusion of heat
in a liquid. In the temperature range from 0 to 30C, this
varies from 0.1809 to 0.284 cm/s for air and from
0.0013 to 0.0015 cm/s for water.
- thermal equator
- An imaginary line connecting those points around the globe
with the highest mean temperature for the given period.
As such, the position of the thermal equator varies with the
season. Due to the thermal inertia of the ocean, the position
of this moves north and south with the Sun but is always
between the Sun and the geographic equator. The mean position
is north of the geographic equator due mainly to the majority
of land masses being in the northern hemisphere.
- thermal expansion coefficient
- A quantity arising from taking derivatives of the density in
representation of the
equation of state.
This is defined in seawater as:
where is the in situ density,
is the salinity, and
is the temperature.
can be obtained from
the International Equation of State of seawater, and
In general, a 0, and -a increase with increasing temperature and
McDougall (1987b) gives a polynomial expression for
(with a similar expression for found in the
saline contraction coefficient
entry used to find just ):
where the rms error of the fit is 0.000894 psu
a check value is 0.34763 psu
at = 40 psu,
= 10.0C and = 4000 db.
See McDougall et al. (1987) and the related
saline contraction coefficient
and adiabatic compressibility.
- thermal wind equations
- These allow the calculation of the
vertical variation of velocity from the density field.
The name thermal is an artifact from the original
meteorological use where the temperature field was used
as a proxy for the density field. In oceanography, the fact
that salinity can also significantly contribute to variations
in the density field leads to the use of density rather than
temperature. The thermal wind equations are derived from
the horizontal equations of motion and the hydrostatic equation,
beginning with the equations of motion reduced to the geostrophic
is the Coriolis parameter, and
the horizontal velocity components, the pressure,
and the density.
The vertical derivative of each equation is taken, the order
of differentiation switched for the pressure, and the
hydrostatic equation (
) substituted to
These equations only give the variation of the velocity with
depth. Further information must be supplied to obtain absolute
- thermobaric coefficient
- A quantity defined as:
where is the
saline contraction coefficient,
thermal expansion coefficient,
and is the pressure.
It can also be defined in terms of the
where is the salinity and
is the potential temperature.
See McDougall (1987b).
- A phenomena related to the pressure dependence of the
thermal expansion coefficient
for the density of seawater.
The dependence of the compressibility of seawater on
both potential temperature
and salinity means that water parcels displaced
laterally without doing any work against gravity will not follow
neutral surfaces defined in terms of
spatially averaged (rather than instantaneous or local) potential
temperature and salinity. They will move off this surface in
a process called thermobaricity.
For example, stirring by mesoscale eddies leads to a net motion
of fluid across neutral surfaces. The process called
cabbeling leads to the same result of
moving fluid across neutral surface, although by mixing at the
molecular level rather than by stirring.
See McDougall (1987b).
- Specifically the depth at which the temperature gradient
is a maximum.
Generally a layer of water
with a more intensive vertical gradient in temperature than in the
layers either above or below it.
When measurements do not allow a specific depth to be pinpointed
as a thermocline a depth range is specified and referred to as
the thermocline zone.
The depth and thickness of these
layers vary with season, latitude and longitude, and local
environmental conditions. In
the midlatitude ocean there is a permanent
thermocline residing between 150-900 meters below the surface, a seasonal
thermocline that varies with the seasons (developing in spring, becoming
stronger in summer, and disappearing in fall and winter), and a
diurnal thermocline that forms very near the surface during the day
and disappears at night. There is no permanent thermocline present
in polar waters, although a seasonal thermocline can usually be
The basic dynamic balance that maintains the permanent thermocline
is thought to be one between the downward diffusive transport of
heat and the upward convective transport of cold water from great
A review of the governing dynamics
of the permanent thermocline can be found in
- thermocline zone
- See thermocline.
- thermoelectric Schlierenmeter
- An instrument used in the mid-20th century to record rapid temperature
changes in the ocean.
It consisted of a constantin wire soldered to copper wires in two
places. One junction was exposed to the sea water, and the other embedded
in compact insulation material.
The thermoelectric current induced depended on the temperature difference
between the two junctions, and was indicated by means of a remote
This instrument therefore measured the temperature difference between
the sea water and the insulated junction rather than the temperature itself.
See Dietrich (1963).
- See thermograph.
- A recording thermometer which measures a continuous trace
of temperature called a thermogram.
The classical version of this featured a bi-metallic strip
attached to a lever holding a pen. As the strip expanded and
contracted in response to temperature changes, the pen moved
across a piece of paper on a drum rotating via some clockwork
mechanim. Such things are done using solid state devices
sending binary data to other solid state devices in these
- In oceanography, descriptive of a combination of temperature and
- thermohaline circulation
- That part of the ocean circulation driven by temporal and spatial differences
in both the salinity and temperature of the waters that comprise the
world ocean. A simplified schematic model of this circulation is the
conveyor belt model.
- thermohaline convection
- See double diffusive convection.
- thermometric depth
- A depth determination that actually represents a pressure determination
and is used more for the determination of the position of bottle
samplers and instruments on research vessels than for the determination
of the depth of the water above the seafloor.
This sort of depth control is needed because of the large wire
angles that can frequently occur when a ship is at station and
currents at depth move the wire away from the vertical position,
causing the true depth of the instruments to not correspond to
the length of the wire.
The method uses two mercury thermometers, one pressure protected which
measures the temperature in situ and the other unprotected and subject
to elastic deformation by the pressure of the water column.
The unprotected thermometer thus registers not only a rise in
mercury corresponding to the in situ temperature but also a rise
proportional to the hydrostatic pressure and, therefore, to the depth.
The accuracy of this method, first determined and extensively
discussed by Wüst during his work aboard the Meteor,
is 20 m at 5000 m depth.
See Dietrich (1963).
- thermosolutal convection
- See double diffusive convection.
- One of two regions into which the ocean depths are sometimes
divided according to temperature, the other being the
psychrosphere. The thermosphere
is the upper regions of the ocean where the temperature is
greater than 10 C. This coincides with the
- A layer where the vertical change of temperature is very small and
displays a local minimum.
- thermosteric anomaly
- The portion
of the specific volume anomaly
that accounts for most of the effects of salinities and temperatures
differing from the standard calculation levels of 35 ppt and 0 C,
respectively. These three terms account for the individual
effects of salinity and temperature perturbations as well as their
- Abbreviation for Tomography System for Monitoring the Western
Mediterranean Basin, a project that started in October 1993 and
was completed in September 1995.
The objective of the project was to use tomography to study
the Western Mediterranean Sea. THETIS-I investigated changes
on the 100 km scale, and THETIS-II was aimed at observing
basin scale heat content changes at scales up to 600 km.
The second experiment consisted of a network of seven moorings
with tomographic transceivers, current meters, and temperature
sensors deployed in January 1994 and recovered in October 1994.
THETIS Web site.
- Thompson, Benjamin (1753-1814)
- See Peterson et al. (1996), p. 48.
- Thomson, Charles Wyville (1830-1882)
- See Peterson et al. (1996), p. 93.
- Thorpe scale
- In a stratified ocean, a vertical profile may contain regions of
static instability. Vertical displacements can be created by
reordering the profile to achieve static stability.
An RMS value of these displacements within a specific depth
range is a length scale called the Thorpe Scale. It can
empirically be related to the
See McDougall et al. (1987).
- Thracian Sea
- The northern part of the Aegean Sea.
- Acronym for Tsunami Hazards Reduction Utilizing Systems
Technology, a NOAA PMEL project
to demonstrate the use of satellite technology with
existing tsunami warning methods to create a low-cost,
reliable, local tsunami warning system.
See Bernard (1991).
- A remote operated vehicle (ROV) developed at
Tiburon Web site.
- tidal bore
- To be completed.
- tidal ellipse
- tidal epoch
- The phase lag of the maximum of a given constituent of an
observed tide behind the corresponding maximum of the
theoretical equilibrium tide.
- tidal evolution
- The changing of the Earth-Moon tidal characteristics over time.
See Kagan (1997).
- tidal friction
- The first quantitative theory of the tidal evolution of the
Earth-Moon system was presented in a series of papers by
George Darwin (Darwin (1879), Darwin (1880b), and
Darwin (1880a)) in the latter part of the 19th century where
he showed that tidal friction can radically change the Moon's
motion and the Earth's rotation on geologic time scales.
One consequence of this theory is that
paleotides had different periods.
See Kagan and Sündermann (1996),
Munk and MacDonald (1960) and
- tidal wave
- An egregious misnomer for a type of wave that
has nothing to do with tides or tide-producing forces.
See the more apt term
seismic sea wave for
- The periodic rising and falling of the water that results from
the gravitational attraction of the moon and sun acting on the
rotating earth. There are related phenomena that occur in the
solid earth and the atmosphere called, strangely enough,
earth tides and
The forces that significantly effect the tides of the oceans
are the gravitational forces of the sun and moon, the centrifugal
force due to the movement of the earth in its orbit, the
Coriolis force, and the frictional
force due to the movement of the water with respect to its
See Cartwright (1999),
Doodson and Warburg (1941),
Douglas et al. (2000),
Emery and Aubrey (1991),
Open University (1989),
Rahman (1988) and
- Tide Chart
- A map showing the water levels throughout a bay or estuary at a particular
point in time. Tide Charts normally show the water levels on an hourly
basis after high tide. They are available for a relatively few locations
around the U.S.
Contrast with Tide Table.
- Tide Table
- A tidal prediction table showing the daily high and low tide predictions
for a particular location. Contrast with
- Acronym for Tsunami Inundation Modeling Exchange, an
- time series
- Any series of observations of a physical variable that is sampled
at changing time intervals. A regular sampling interval is usually
presumed although not required.
- time step
- The basic unit of temporal resolution in a numerical model
created by discretizing a continuum
differential equation to create an analogous discrete algebraic
equation. The model time advances by discrete steps as opposed
to the (at least perceived) continuum nature of time in the
- Timor Sea
- A regional sea located in the
Australasian Mediterranean Sea and centered at about
12 S and 127 E. It consists of Timor
Strait to the north and the Sahul Shelf to the south,
with the former having a width of 80 km and a maximum
depth of 3 km in the Timor Trench. Sills to the
west (1860 m) and east (1400 m) control the allowable
flow at depth. Overall, the flow is strongest in the strait
and extends with decreasing velocities onto the shelf.
Current measurements show a transport from east to west on the order of
7 Sv through the strait and a seasonally varying 1-3 Sv
on the shelf. The currents on the shelf flow northeastward
along the shelf (to about 12.5 S where they turn more
northward) from September until January. The onset of the
monsoons in March turns the flow toward the southwest which
continues until September, except near the coast where the
southwestward flow reverses in May.
See Cresswell et al. (1993).
- Abbreviation for Tropical Instability Waves Experiment, a project
of the APL of the University of
Washington Department of Oceanography.
This study, taking place from 1990-1991, studied the life cycle
and energy sources for
tropical instability waves
in the eastern Pacific.
See Qiao and Weisberg (1995).
- Tizard Deep
- See Brazil Basin.
- TMA spectrum
- A wave spectrum developed to incorporate
finite depth effects into the
See Bouws et al. (1984).
- Abbreviation for Thermal Modeling and Analysis Project.
TMAP Web site.
- Abbreviation for TOPEX microwave radiometer, an instrument on the
The TMR measures sea surface microwave emissivity at three
frequencies (18, 21, and 37 GHz) to estimate to total water
vapor content in the atmosphere. This estimate is used to
correct to the water vapor-induced errors in the altimeter
measurement. The 21 GHz channel is the primary channel for water
vapor measurement, with the 18 GHz and 37 GHz channels used to
remove the effects of wind speed and cloud cover, respectively.
See Ruf et al. (1994).