- Abbreviation for Instituto Nacional de Meteorología e
Hidrología, located in Ecuador.
- Acronym for Inlet and Nearshore Dynamics Experiment: Algarve.
See the INDEA Web site.
- Acronym for Indian Ocean Experiment, which took place from 1976-1979.
- independent variable
- See dependent variable.
- Indian Central Water (ICW)
- See Poole and Tomczak (1999).
- Indian monsoon
- The seasonal reversal of the wind direction along the shores
of the Indian Ocean, especially in the Arabian Sea. The winds
blow from the southwest during half of the year and from the
northeast during the other half. The reversal of direction
(from that due to the normal zonal circulation pattern) is due
to the effects of
as the Himalayan plateau heats up during the summer, causing
the air to rise and be replaced by the warm, moist air from
over the Indian Ocean.
- Indian Ocean
- Much, much more later.
See Sparrow et al. (1996),
Stramma and Lutjeharms (1997),
Shetye and Gouveia (1998) and
Ganachaud et al. (2000).
- Acronym for the Indien Gaz Ocean project, a series of three
cruises taking place aboard the RV Marion Dufresne from
INDIGO 14C activities
are available from
- Acronym for Indian Ocean Experiment, a project whose goal is to study
natural and anthropogenic climate forcing by aerosols and feedbacks on
regional and global climate.
It will incorporoate field studies where pristine air masses from the
southern Indian Ocean including Antarctica and not-so-clean air from
the Indian subcontinent meet over the tropical Indian Ocean to provide
a unique natural laboratory for studying aerosols.
- INDOMED Expedition
- A research expedition taking place from 1977-1979.
See Scripps Institution of Oceanography (1979b).
- Indonesian throughflow
- See Godfrey (1996).
- INDOPAC Expedition
- See Scripps Institution of Oceanography (1978).
- Indo-Pacific Deep Water
- See Yu et al. (1996).
- inertial circles
- The paths followed by
- inertial dissipation method
- An observational technique for inferring the ocean surface
wind stress magnitude.
See Fairall and Larsen (1986) and
- inertial frequency
- The frequency f of rotation of
- inertial motion
- See inertial wave.
- inertial oscillation
- See inertial wave.
- inertial wave
- A limiting form of a long
that oscillations at the
In this limit the effects of gravity are negligible and
the fluid particles are moving under their own
inertia, whence the name.
See Webster (1968) and
- infragravity wave
- More later.
- infralittoral zone
- The third (from the top) of seven zones into which the
benthos has been divided.
This has also been called the inner sublittoral zone.
See Fairbridge (1966).
- That part of the electromagnetic radiation spectrum from approximately
0.75 to 1000 m. This is between the visible and microwave
regions of the spectrum. It is further divided into the
near (0.75 to 1.5 m), intermediate (1.5 to 20 m),
and far (20 to 1000 m) ranges. Most of the energy emitted
by the Earth and its atmosphere is at infrared wavelengths, and it
is generated almost entirely by large-scale intramolecular
processes. The tri-atomic gases such as water vapor, CO2,
and ozone absorb infrared radiation and play important roles
in the propagation of infrared radiation in the atmosphere.
- inland sea
- A sea surrounded by land and connected to the open ocean
by one or more narrow straits. Examples include the
Baltic Sea, the
Red Sea, and the
Compare to epeiric sea and
- Acronym for International Maritime Satellite Organization.
- inner sublittoral zone
- See infralittoral zone.
- Abbreviation for Institute for Naval Oceanography.
- A part of JONSDAP 76.
- Acronym for Subarctic North Pacific Hydrographic Surveys, a cooperative
program among Russia, the U.S. and Canada from 1991-1993 that addressed
the variability of the circulation in the subpolar and northern
subtropical gyres of the North Pacific.
- The zone or portion of a beach profile extending seaward from
the foreshore to just beyond the
See Komar (1976).
- Inshore Countercurrent
- One of the two narrow, poleward-flowing boundary currents in
the California Current system
(the other being the
The IC has been reported as a seasonal flow, appearing in fall and
winter. It is found over both the shelf and slope and transports
shallow, upper ocean waters derived largely from CC waters with some
modification by coastal processes.
This is sometimes called the Davidson Current or Davidson Inshore
Current at locations north of Point Conception.
See Collins et al. (2000).
- Inshore Peru Current
- The name sometimes given to the combination of the
Chile Coastal Current (CCC) and the
Peru Coastal Current (PCC).
- in situ data
- Data associated with reference to measurements made at the
actual location of the object or material measured, by
contrast with remote sensing (i.e., from space).
- The radiation received from the Sun.
- Acronym for International Northern Sea Route Project, a program
organized by the Fridtjo Nansen Institute in Norway.
- instrument error
- An error that is a function of the instrument design and the ambient
conditions under which it must operate. For example, the mercury
barometer for surface (not mean sea level) pressure measurements
has an expected instrument error of about 0.25 mb for a single
reading due to ambient temperature and wind effects.
See Daley (1991).
- instrumental data
- This refers to data, e.g. temperatures, rainfall amounts, atmospheric
pressure, etc., that have been gathered via direct measurement as
opposed to proxy data. Most of these records
(at least the reliable ones) are on the order of a hundred years or
less in duration, with perhaps the longest being a temperature
record for central England prepared by Manley (1974)
that extends back to 1659.
- Acronym for Instituto de Tecnología y Ciencias Marinas, located
- intensive parameter
- A determining parameter of a system that does not depend on the
size and mass of the system, e.g. temperature, pressure,
and concentration, as opposed to an
- interbasin exchange
- In physical oceanography, the active exchange of
waters and/or water mass
properties between basins.
Evidence for this process is provided by the similarities in
water masses in the three major oceans despite quite different
water mass conversion processes in each.
The three avenues for this in the world ocean are: the Bering
Strait, which provides a conduit for North Pacific-North Atlantic
exchange via the Arctic Ocean; passes in the Indonesian
Archipelago, which connect the Indian and Pacific Oceans at
low latitudes; and the Southern Ocean, in which the
ACC flows through several broad passages
between Antarctica and the other southern hemisphere continents.
The conveyor belt paradigm was
the first attempt to tie these together into a unified
theory of interbasin circulation.
The most up-to-date scenario for these interbasin circulation
processes starts with 14 Sv of upper and intermediate level
water being converted to NADW in the
North Atlantic and flowing southward across the equator to
join the ACC. This loss from the Atlantic
is compensated by 10 Sv of upper level entering via the
Drake Passage and 4 Sv entering
from the Indonesian throughflow
Australasian Mediterranean and around Africa. The Indian Ocean
receives 24 Sv of lower level cold water from the ACC, returning
14 Sv as cold water and transforming 10 Sv to upper level water.
This latter 10 Sv flows south of Australia, across the South
Pacific, and through the Drake Passage into the
Benguela Current regime. This
joins the afore mentioned Indonesian Throughflow, crosses the
equator, and flow with the Gulf Stream into the North Atlantic
to replace the lost NADW. The Pacific takes 20 Sv of cold
water from the ACC and returns it as less cold water, with about
half of it traversing the North Pacific.
This is a simplified two-layer version of a more complicated
four-layer circulation scheme developed by
Schmitz (1995) which includes intermediate and
upper layer compensations flows as well as abyssal and
deep interbasin thermohaline circulation layers.
The greatest uncertainties remain in the Indian and Pacific
Oceans, especially with the flows associated with vertical
exchange, which in itself is perhaps the least well established
feature of ocean circulation.
- A device, e.g. imaging radar, that uses two different paths for
imaging and deduces information from the coherent interference
between the two signals. Paths with spatial and temporal differences
have been used to measure, respectively, terrain height and
- intermediate models
- A class or group of equations that have been formulated in an attempt
to extend the formal validity of the
quasi-geostrophic equations while also avoiding the complications
of the full primitive equations.
The usual approaches attempt to extend the
planetary geostrophic equations.
This is done by either proceeding to a higher order in an asymptotic
expansion (or similar procedure) in the
Rossby number (or some other small
parameter) or by attempting to extend the validity of the equations
at their lowest order.
A disadvantage of the former approach is that it does not extend
the regime of validity of the new equations beyond that of the
lowest order system.
The latter approach, usually less mathematically formal, attempts
to include terms neglected or inaccurately approximated in the
original equations which restrict their range of applicability.
These include terms involving large variations in depth, Coriolis
parameter, and the advection of relative vorticity.
The ultimate goal is to develop a set of equations valid for
both planetary and synoptic scales.
See Mundt et al. (1997).
- internal Froude number
- See Froude number.
- internal tide
- Internal waves somehow excited at or
near tidal periods. It is generally accepted that these are
generated by energy scattered from surface to internal tides
by bottom roughness.
See Hendershott (1981), p. 329.
- internal wave
- A gravity wave propagating in the interior of the ocean with
typical spatial and temporal scales of kilometers and hours.
The amplitudes are on the order of 10 meters, much larger than
their surface counterparts.
Internal waves can be classified according to the density distribution
of the fluid in which they propagate:
- interfacial waves, which occur at the interface of a two-fluid system;
- plane waves, which occur when the density of the fluid increases
linearly with depth; and
- waves of mixed type, which included internal waves occuring in a fluid
whose density varies continuously, but not necessarily linearly.
Peter Rhines reviewed recent progress in understanding internal
waves (at the APROPOS conference). His
remarks give some of the overall flavor of internal wave research
Internal wave research reached a feverish pitch in the 1970s
as an appreciation for the spectrum of observed waves was gained, and
weak interaction theory produced useful results about the production
of turbulent mixing, and induction of mean currents. The theory of
critical-layer absorption and reflection (where the mean flow
speed U equals the phase speed, c, of the wave in the direction of mean
flow) showed us how such interactions can also be "strong", and
localized in space. Generally, the power of geometrical optics (ray
theory) was demonstrated in wholly new classes of problems. Attention
then drifted toward nonlinear waves that are outside of the
random-phase approximation of triad interaction theory: solitary
waves and undular bores for example. Inverse-scattering theory
allowed one to trace uniquely the distribution of solitons emerging
from complex initial conditions. This gives one of many examples
where a significant GFD discovery (here traceable back to
Scott-Russell riding along canals in Victorian England on horseback )
radiated outward into many areas of physics and engineering.
Briscoe (1975a) and
- International Hydrographic Bureau
- More later.
- International Hydrographic Organization
- More later.
- International Indian Ocean Expedition (IIOE)
- A research program under which scientists of twenty-two
nations collected data in the Indian Ocean from 1959-1965.
This was done under a plan coordinated by the
Scientific Committee on Oceanographic Research (SCOR)
of UNESCO. See Currie (1966).
- International Year of the Ocean (IYO)
- The United Nations declared 1998 to be the International Year of the
Ocean with the overall objective being to focus and reinforce the
attention of the public, governments and decision makers at large on the
importance of the oceans and the marine environment as resources
for sustainable development.
- Irish Marine Institute
- A national agency of Ireland whose mission is to undertake, coordinate,
promote and assist in marine research and development and provide
such services related to ma rine research and development that, in
the opinion of the institute, will promote economic development
and create employment and protect the environment.
IMI Web site.
- Iselin, Columbus O'Donnell (1904-1971)
- See Stommel (1993) (reprinted in first volume of Stommel's
- Acronym for Irish Marine Data Center, a part of the
Irish Marine Institute that
collects, manages, processes, quality controls, and archives data
collected by Irish institutions.
ISMARE Web site.
- International Ship Operators (ISO)
- An open international forum of research ship operators from
14 countries and representatives of EC, FAO and OCEANIC
who meet annually to discuss research fleet
barter/exchange arrangements and research fleet status
as well as report on staff exchanges and lost equipment.
ISO Web site.
- Intertropical Convergence Zone
- A narrow low-latitude zone in which air masses originating in the
northern and southern hemispheres converge and generally produce
cloudy, showery weather. Over the Atlantic and Pacific it is
the boundary between the northeast and southeast trade winds. The
mean position is somewhat north of the equator, but over the
continents the range of motion is considerable. Often abbreviated
- In dynamical systems theory, a system is said to be intransitive if
different sets of initial conditions evolve to more than one
alternative resultant state. Compare to transitive
and almost intransitive.
See Lorenz (1979).
- Acronym for INTegration of Ice-core, MArine and TErrestrial data
for the North Atlantic region from 25 to 9 ka BP. The goal of
project is to integrate data sets from ice-core, marine
and land records to produce a series of paleoenvironmental
maps for the interval between the
Last Glacial Maximum and
the Early Holocene. The primary
objective is to study the ice-sea-land-atmosphere interactions
and the feedbacks operating during a glacial-interglacial
See Walker et al. (2001).
- intrinsic frequency
- See buoyancy frequency.
- inventory-box model technique
- A method for analyzing transient tracer data where a time
dependent box model is used to simulate the inventory or
mean concentration of a tracer in a prescribed reservoir.
The model is driven by the time dependent surface water
concentration and parameters representing exchange times
or volume transports are determined by fitting the model
See Sarmiento (1988).
- inverse methods
- More later.
- inverted echo sounder (IES)
- An instrument used to monitor oceanic fronts since
Rossby (1969) first introduced the concept of using variations
in acoustic travel time to measure changes in the depth of the
They were initially deployed in the MODE
project and have been used extensively in many other regions.
The use of an IES requires calibration of travel time measurements
into other scientific quantities of interest, with calibration
requiring knowledge of the variations in temperature and salinity
stratification and the resulting density and sound speed profiles
in the region where the IES is to be deployed.
See Watts and Rossby (1977).
- Abbreviation for Intergovernmental Oceanographic Commission, a
commission that focuses on promoting marine scientific
investigations and related ocean services, with a view to learning
more about the nature and resources of the oceans.
The four themes on which the IOC focuses are:
The IOC is composed of an Assembly, an Executive Council,
a Secretariat, and a number of Subsidiary Bodies.
The Assembly meets every two years and consists of one seat for
each member state, of which there are currently 125.
The Executive Council meets every year and is elected by the
The Secretariat is the executive arm and is headed by an Executive
Secretary elected by the Assembly. It ensures the implementation
of activities decided upon by the Assembly.
- to develop, promote and facilitate international oceanographic
- to ensure effective planning, establishment and co-ordination
of an operation global ocean observing system;
- to provide international leadership for education and training
programs as well as technical assistance for systematic observations
of the global ocean; and
- to ensure that ocean data and information are efficiently
handled and made widely available.
The presently (1998) constituted Subsidiary Bodies are divided
into scientific/technical and regional categories.
The former category includes:
The latter includes:
- Ocean Science in Relation to Living (and Non-Living) Resources (OSLR and
- Ocean Mapping (OM),
- Marine Pollution Research and Monitoring (MPRM),
- Global Ocean Services System,
- Ocean Observing Systems, and
- Oceanographic Data and Information Exchange.
- the Sub-commission for the Caribbean and
Adjacent Regions (IOCARIBE),
- the Regional Committee for the Southern Ocean (IOCSOC),
- the Regional Committee for the Western Pacific (WESTPAC),
- the Regional Committee for the Co-operative Investigation of the North
and Central Western Indian Ocean (IOCINCWIO),
- the Regional Committee for the Central Indian Ocean (IOCINDIO),
- the Regional Committee for the Central Eastern Atlantic (IOCEA),
- the Regional Committee for the Black Sea (IOBS), and
- the Joint IOC-WMO-CPPS Working Group on the Investigations of
IOC services available online include:
IOC Web site.
- IAMSLIC, a directory of aquatic libraries;
- GLODIR, a directory of ocean scientists;
- Ocean Pilot, a guide to Web resources;
- an International Marine Meeting List; and
- an Electronic Library containing many recent publications
in PDF format.
- Acronym for IOC Sub-commission for the
Caribbean and Adjacent Regions.
- Abbreviation for IOC Committee for Training,
Education, and Mutual Assistance in the Marine Sciences, formerly
known as TEMA.
- Abbreviation for IOC Voluntary Cooperation
- Abbreviation for the ICES
Oceanographic Data Center, a bank of oceanographic
data supplied by ICES member countries that dates back
to the early 1900s.
IODC Web site.
- Acronym for International Oceanographic Data and Information Exchange,
an IOC project established in 1961 to ``enhance marine research,
exploration and development by facilitating the exchange of
oceanographic data and information between participating member
The IODE system is composed of a committee which governs the
development and operations of the system and a number of data
centers that carry out the activities established by the
committee. The data center structure is composed of three components:
NODCs, RNODCs, and
- Abbreviation for the International Oceanography Foundation, whose
mission is to encourage scientific investigation of the sea amongst
other things. See the IOF Web site.
- Acronym for International Ocean Network, a committee established in
June 1993 with the goal of facilitating international cooperation
in the development of ocean botton observatories. While originally
created for the purposes of seismology, in 1995 it was enlarged to
include all geosciences.
- Ionian Sea
- One of the seas that comprise the eastern basin of the
It is surrounded by Italy, Hellas, Libya and Tunisia, and
has a volume of 10.8
It connects to the Cretan Sea via the Kithira (160 m deep, 33 km wide)
and Antikithira (700 m deep, 32 km wide)
Straits, the Levantine Sea via the
Cretan Passage, the western Mediterranean via the Strait of
Sicility, and the Adriatic Sea via
Otranto Strait (780 m deep, 75 km wide).
The major water masses of the Ionian Sea are
Modified Atlantic Water (MAW),
Levantine Intermediate Water (LIW), and
Eastern Mediterranean Deep Water (EMDW).
The MAW spreads eastward from the Sicily Straits in the surface
layer and is identified as a subsurface salinity minimum between
30 and 200 m depth. It overlies the LIW that enters through the Cretan
passage and is identified by a salinity maximum between 200 and 600
m depth. Below this, the colder and less saline EMDW, the main source
of which is Adriatic Deep Water (ADW),
occupies the layers below 1600 m. A transitional mixture of LIW and EMDW
occupies the range between 700 and 1600 m. In the summer
Ionian Surface Water can be differentiated
from the MAW as saltier and warmer.
Prominent circulation features in the upper thermocline and
intermediate layer include the Atlantic-Ionian Stream (IAS),
the Ionian Anticyclones (IA), the Pelops Anticyclone (PA),
the Mid-Mediterranean Jet (MMJ), and the Cretan Cyclone (CC).
The AIS enters the Ionian Sea from the northwest via the Sicily
Straits, meanders west and then south, and then turns northeast
to flow between Sicily and the IA.
At around 17 E and 37 N it bifurcates, with a
southward flowing branch combining with the IAS to the west
to form the IA region.
The northeastward flowing branch continues
to the heel of Italy where it turns to the south and flows past the
PA, continuing past there until it passes to the south of the CC
and turns west through the Cretan passage, becoming the MMJ.
See Fairbridge (1966) and
Malanotte-Rizzoli et al. (1997).
- Ionian Surface Water (ISW)
- A water mass formed at the surface in
the Ionian Sea.
See Malanotte-Rizzoli et al. (1997).
- Abbreviation for Institute of Oceanology of the Polish Academy of
Sciences, founded in 1983 as the successor to the Marine Station
of the Academy in existence in Sopot since 1953.
The institute is divided into departments for marine physics,
hydrodynamics, marine chemistry and biochemistry, and
IO-PAS Web site.
- Abbreviation for Institute of Ocean Sciences, a research facility of
the Canadian Department of Fisheries and Oceans (DFO).
The IOS is located in Sidney, British Columbia and is one of a network
of nine major scientific facilities across Canada run by the Science
Sector of the DFO.
IOS Web site.
- Abbreviation for the Institute of Oceanographic Sciences, Deacon
Laboratory, an institute whose mission is to advance understanding
of the ocean environment and processes of environmental change
in the oceans and to predict future change by carrying out
multidisciplinary studies on the oceans and their boundaries with
the air and seabed. More information can be found at the
IOSDL Web site.
- Abbreviation for Instituto Oceanografico da Universidade de Sao
- Abbreviation for International Program for Antarctic Buoys.
- Acronym for Intercepted Photosynthetically Active Radiation.
- Acronym for IGOSS Pilot Project on
Altimetric Sea Surface Topography Data.
- Abbreviation for
Indo-Pacific Deep Water.
- Abbreviation for Indo-Pacific Sea Level Network.
- See ITS-90.
- See ITS-90.
- Iribarren number
- A surf similarity parameter developed by Battjes in 1974.
It is expressed as:
where is the breaker height measured at the toe of
is the beach slope angle, and
the deep water wavelength, i.e.
where is the wave period.
The Iribarren number is used to generally predict when various beach states are
likely to occur.
The states are spilling (
- Irish Sea
- A marginal sea located between Ireland and Wales. It extends
from the Mull of Galloway in the north to a line connecting
St. David's Head (in Wales) to Carnsore Point (in Ireland)
in the south.
See Bowden (1955), Fairbridge (1966) and
- Irminger Current
- A branch of the
North Atlantic Current
that curves north near Iceland, where a minor part of it
splits to flow north along the west coast of Iceland and the
major part curves to the west and joins the southward flowing
East Greenland Current.
Both branches ultimately rejoin the North Atlantic Current.
The transport of this current has been estimated ar
about 8-11 Sv.
See Fairbridge (1966) and Tomczak and Godfrey (1994).
- Irminger Sea
- A body of water in the North Atlantic recognized as such for
oceanographic if not official purposes. It lies roughly
between the east coast of Greenland and the west coast of
Iceland, with the Labrador Sea
on its southwest corner and the
Greenland Sea to the northeast.
The southern boundary is marked by hydrographical
rather than geographical features.
The basin of this sea is mostly occupied by the eastern
part of the Labrador Basin which ranges up to 4600 m in depth.
The chief circulation feature is
the Irminger Current.
- IronEx I
- An experiment taking place in October 1993 that marked the first
attempt to experimentally manipulate an ocean ecosystem.
A single pulse of iron was added to a 64 square kilometer patch of
water in the eastern equatorial Pacific
The fertilized patch was tracked using a Chl fluorescence and a
sulfur-hexafluoride (SF6) inert tracer.
After 2 to 3 days researchers measured a doubling of phytoplankton
biomass, a tripling of Chl, and a fourfold increase in net
primary productivity (NPP), with no measureable drawdown of either
NO3 or CO2.
See Martin et al. (1994) and
Coale et al. (1998).
- IronEx II
- The follow-up to IronEx I in which a 64 square
kilometer area of the ocean in the eastern equatorial Pacific was fertilized
three times over a week with a total of 225 kg of FeSO4. The repeated
pulsing was used to prevent the rapid sedimentation that occurred in
The patch was again tracked with Chl fluorescence and SF6, and a drogued
drifter was deployed in the center of the patch to make it easier to follow.
The patch persisted for 19 days, drifting 10 to 100 km per day. The
observed consequences included:
See Coale et al. (1996) and
- a doubling in phytoplankton growth rates;
- an increase in CHl by a factor of 25;
- a decrease in NO3 by 50%;
- a 15X increase in NO3 uptake;
- a decrease in ocean to atmosphere CO2 flux by 60%;
- growth due mostly to large diatoms, which accounted for 15% of
total phytoplankton before and 85-98% afterwards; and
- a doubling of micro- and mesozooplankton biomass.
- IronEx III
- This has apparently been renamed SOFeX.
- iron hypothesis
- The hypothesis that iron plays a major regulatory role in
While the potential role of iron as a limiting factor in phytoplankton
productivity was appreciated by researchers as early as the 1930s,
it wasn't until John Martin convincingly pieced together several
lines of evidence in the late 1980s that the oceanographic community
gave notice to the point of planning major experiments to test it.
The threads of Martin's argument included that:
See Chisolm (1995).
- the primary source of iron to the surface waters of the oceans is
from the land;
- the dissolved iron concentrations in offshore areas are extremely
low, i.e. two orders of magnitude less than thought by the investigators
in the 1930s;
- atmospheric dust deposition in the two major high nutrient, low
chlorophyll (HNLC) areas of the oceans - the Antarctic and equatorial
Pacific Oceans - are the lowest in the world; and
- laboratory experiments in which bottles filled with surface waters
from NHLC regions and incubated at simulated in situ light and
temperature for about a week showed that iron-enriched bottles always
ended up with higher total chlorophyll that the control bottles without
- The radiant energy that passes through a unit horizontal area per
unit time coming from all directions above it. The irradiance
is defined by
where is the radiance, the
and the infinitesimal solid angle.
The rate at which radiation is incident upon a unit area.
- In geophysical fluid dynamics this refers to fluid motion in which
there is no vorticity.
- Abbreviation for International South Atlantic Buoy Program, a
- A contour line on a weather map that signifies the location of
equal changes of pressure over a specified period.
- isallobaric wind
- A theoretical wind component originating from the spatial
non-uniformity of local rates of change of pressure.
- isentropic coordinates
- The replacement of the z coordinate in an x-y-z coordinate system
with the potential temperature. This can be done when horizontal
scales are large compared to vertical scales, i.e. when the
can be made. See Gill (1982), p. 180.
- Acronym for Inner Shelf Transfer And Recycling, a program for
investigating ocean processes in and near the Bering Strait.
- Abbreviation for In-Situ Heat Transfer Experiment, a project
of the APL of the University of Washington
School of Oceanography.
- Abbreviation for IGOSS
Sea Level Program in the Pacific, a program established for
the purpose of making monthly mean sea level data
available to a wide circle of users in a timely
fashion and to generate products that would be
valuable for scientific analysis of climate-related
ISLP-PAC Web site.
- Acronym for
International Ship Operators.
- In physical oceanography, a contour of constant pressure.
- Descriptive of a surface that is an isobar.
- isobaric coordinates
- The replacement of the z coordinate in an x-y-z coordinate system
with the pressure. This can be done when horizontal scales are large
compared to vertical scales, i.e. when the
can be made. This set of coordinates is widely used in
See Gill (1982), p. 180.
- isobaric surface
- A surface on which the pressure is everywhere the same.
- See isopleth.
- In physical oceanography, a contour of constant salinity.
- A general term referring to lines drawn on a map or chart to
display the distribution of any element, each line being drawn
through places at which the element has the same value. See,
for example, isohaline,
isobar, etc. Isogram is sometimes used as
- In physical oceanography, a contour of constant density.
- isopycnal form stress
- A horizontal pressure force averaged in longitude and time
over a material surface of constant potential density.
This is associated with a combinatino of transient
(mesoscale) and standing (time-mean, longitudinally varying)
See McWilliams (1996).
- isopycnal method
- A scheme to systematize the classification of the
hydrography of the oceans
developed by Montgomery in the late 1930s. He developed this
to overcome limitations he saw in the earlier
core layer method of Wust.
In this method variable properties (e.g. salinity, temperature, etc.)
are examined on surfaces of constant
along which it is assumed that maximum mixing and flow occur.
The variations in depth of such surfaces can also be used as a diagnostic
tool for locating
geostrophic currents since rapid
changes in depth are indicative of their presence.
The isopycnal method was originally applied such that all
densities were calculated relative to the ocean surface, i.e. as
either sigma-t or
sigma-. This was later
modified when it was found that, due to the nonlinearity of the
equation of state for seawater, maximum values could exist well
above the ocean bottom - ostensibly signifying a hydrostatic
instability. The problem was rectified by the use of
potential densities calculated relative to different pressures
as was required by the situation, i.e. sigma-1 for densities
relative to 1000 decibars (db),
sigma-2 for 2000 db, etc., a procedure that is still followed
- Acronym for International Southern Ocean Studies, a program to
study the Southern Ocean,
especially the fronts and energetics in the regions of
Drake Passage and southeast
of New Zealand. The monitoring of the transport of the
Antarctic Circumpolar Current also had high priority.
- The tendency of the crust of
the earth (i.e. the
lithosphere) to maintain a near equilibrium
state in relation to the denser, underlying
asthenosphere or upper mantle. For
example, a continental block might sink or rise due to the presence
or absence of an ice sheet in a process called glacial isostatic
- In meteorology, a line on a chart joining points of equal
specific volume, the volume of
- In meteorology, a line or contour of constant wind speed. An
alternative is isovel.
- In physical oceanography, a contour of constant temperature.
- Each of two or more varieties of a particular chemical element
which have different numbers of neutrons in the nucleus, and therefore
different relative atomic masses and different nuclear (but the
same chemical) properties.
- isotope dilution analysis
- A technique for determining the unknown quantity of an element of
known isotopic composition. A spike, i.e. a known
quantity of the same element with a known different isotopic
composition, is mixed with the sample and the composition assessed
via the resulting isotopic composition of the mixture.
- isotope fractionation
- See Fairbridge (1966).
- isotope reference standards
- Neither absolute abundances of minor isotopes nor absolute values
ratios can be determined accurately enough for geochemical
purposes. As such, differences in such absolute isotopic ratios
between two substances are substituted. These comparisons are made
between the laboratory samples and various internationally accepted
standards known as isotope reference standards. Examples of these
are SMOW (standard mean ocean water) and V-SMOW (a SMOW artificially
prepared in Vienna) for oxygen and PDB (a Cretaceous belemnite)
and V-PDB (the same prepared in Vienna) for oxygen in carbonates.
See Bowen (1991) for a thorough discussion.
- isotope stage
- A division of a deep-sea core on the basis of oxygen isotope ratios.
There have been 19 isotope stages since the reversal of the Earth's
magnetic field 700,000 years ago.
- See isotach.
- Acronym for
Iceland-Scotland Overflow Water.
- Istrian Coastal Countercurrent (ICCC)
- See Supic et al. (2000).
- Abbrevation for
Ionian Surface Water.
- Abbreviation for the International Turbulence Comparison Experiment,
performed in Australia in 1976.
See Kraus and Businger (1994).
Intertropical Convergence Zone.
- Abbreviation for International Tsunami Information Center,
established in Nov. 1965 by the IOC.
The ITIC monitors the activities of the Tsunami Warning
System in the Pacific, making use of 31 seismic stations,
79 tidal stations, and 101 dissemination points scattered
across the Pacific. It also has a public education program
directed towards coastal residents and other interested parties.
ITIC Web site.
- Abbreviation for International
TOGA Project Office.
- Abbreviation for Integrated Tsunami Research and Information System.
- Abbreviation for International Temperature Scale of 1990, a temperature
scale approved by the International Committee for Weights and Measures
at its annual meeting in September 1989.
It replaces the International Practical Temperature Scale of 1968
(IPTS-68) and took effect on Jan. 1, 1990.
ITS-90 takes advantage of technological advances and more
closely approximates the thermodynamic temperature scale than
The features of oceanographic interest were outlined by
Of particular interest to oceanographers are the properties of
ITS-90 in the range -2C to +35. The single
most important property is that the triple point of water remains
unchanged at 273.16 K or 0.010C; however at standard
atmospheric pressure the boiling oint of water falls to
99.974C. Consequently in the interval 0-100C temperatures
measured on the ITS-90 scale are lower than values measured on the
IPTS-68 scale. But below 0 they are higher.
The differences are expressed in the following table.
Over this range (although slightly nonlinear) the relation between
the temperature scales can be adequately represented by the expression
Initially it is expected that oceanographers will employ the above
expression to correct temperatures measured on the IPTS-68 scale but
new calibration procedures will be introduced in National Standards
Laboratories commencing 1990 and it is hoped these practices will
rapidly spread to oceanographic calibration facilities.
The value for the fixed points on the ITS-90 scale and the instruments
and interpolation equations to be employed for the measurement
of temperature are described in a text to be published in the
Journal Metrologia, early in 1990.
Although the impact of the new temperature scale on ocean temperature
measurements and their climatology is likely to be small (or even
negligible), unfortunately this is not true for its knock-on effects.
Corrections will be required for the computation of salinity and other
state properties of sea water.
The conversion between IPTS-48 and
IPTS-68 is given by
- Acronym for Internal Wave Experiment.
See Briscoe (1975b) and
Müller et al. (1978).
- Abbreviation for Intergovernmental
WOCE Panel, a subsidiary body of the
IOC and the WMO
established to meet the scientific, managerial, implementation,
and resource needs of WOCE. See the
IWP Web site.
- Abbreviation for International Weddell Sea Oceanographic Expedition.
- Abbreviation for ICES International
Young Fish Survey, a project that has been undertaken in
every year in January/February in the North Sea since about 1970.
This survey includes station observations of hydrochemical
measurements which has resulted in a comprehensive North
Sea data set of over 20 years duration. Maps of the temperature
and salinity distributions measured during these surveys can be
obtained at the
IYFS Web site.
- Abbreviation for
International Year of the Ocean.