- Labrador Basin
- A ocean basin situated between Labrador, Greenland and
Newfoundland. It underlies the
Labrador Sea as well as most
of the Irminger Sea.
- Labrador Current
- A current that
flows southward over the continental shelves and slopes of
Labrador and Newfoundland from Hudson Strait at 60N to
the Tail of the Grand Banks of Newfoundland at 43N.
It was first described by Smith et al. (1937) as
a continuation of the
Baffin Island Current, which
transports the cold and relatively low salinity waters flowing out
of Baffin Bay, and the warmer and more saline waters of a branch of the
West Greenland Current.
It appears as two branches at Hamilton Bank on the southern
Labrador Shelf, a small inshore stream carrying about 15% of the
transport and the main stream over the upper continental slope
carrying about 85%.
Measurements indicate that the Labrador Current carries a transport
(relative to 1500 db)
of 3.80.9 Sv, 85% of which occurs in a 50 km wide jet over the
shelf break between the 400 and 1200 m isobaths.
An additional barotropic component has been identified over the
1000 m isobath. It has a maximum monthly speed of about 0.09 m s, which
adds about 7.2 Sv to the transport estimate.
Another southward flow has been identified over the 2500 m isobath
from current meter observations, seaward of the traditional Labrador
Current. The southward flow is over the full water depth, with
a current half-width of order 70 km.
This flow is weakest in summer and strongest in winter, as opposed
to the baroclinic Current being strongest in late summer and weakest
It is speculated that the traditional Labrador Current over the
upper slope is primary buoyancy driven, while the deeper current
centered at the 2500 m isobath is part of the North Atlantic
See Lazier and Wright (1993) and
Han and Tang (1999).
- Labrador Sea
- A part of the north Atlantic recognized as a separate body of
water for hydrographic purposes although not officially recognized
as such. The southern boundary is a line from the southern tip
of Greenland to Cape St. Charles on the coast of Labrador and the
northern boundary the 66 N latitude line that joins Greenland
and Baffin Island north of the Arctic Circle.
The circulation features include the
West Greenland Current
and the Labrador Current.
The Labrador Sea is part of the pathway through which the
low salinity outflows of the Arctic Ocean move southward and
downward toward denser surfaces. This low salinity can follow
two pathways: mixing across fronts and subsequent incorporation
into the subpolar and eventually the subtropical gyre circulation; or
the water can move offshore into the
Irminger Seas and be mixed down the
following winter as
Irminger Sea Water or
Observations indicate considerable fluctuations of salinity
in the upper waters on both a seasonal and interannual basis,
which renders it difficult to create an average picture of
the hydrography from historical data (of which there is much
in this region). Climatologically, this is a region where
the first effects of atmospheric warming induced by CO2 or
other greenhouse gases might be seen. Milder winters would
lead to less overturning and accumulation of low salinity
waters in the upper layers, an affect which would be exacerbated
by increased glacial and polar ice melt as well as increased
high latitude precipitation. This could very well turn off the
production of LSW with possible global consequences.
See Tomczak and Godfrey (1994) and
U. S. Science Steering Committee for WOCE (1986).
- Labrador Sea Convection Experiment
- An experiment whose purpose is to improve the understanding of the convective
process and therefore the fidelity of parameteric representations
used in large-scale models by a combination of field observations,
laboratory studies, theory and modeling.
The goals of the experiment are to investigate:
- the characteristic scales and properties of convective plumes;
- how plume parameters depend on the forcing and local environment;
- the fluxes of mass, heat and salt from the ensemble of plumes;
- how convection is related to its mesoscale environment;
- the relative importance of lateral (eddy) versus vertical
(convective) flux of heat and salt inside/outside the convective region;
- what controls the volume and T/S properties of created
- how the convected water mass is accomodated into the general
- the mean and seasonal variation in the gyre circulation.
The field work for this experiment includes floats and drifters,
basin-wide hydrographic surveys, moored instruments to measure the
usual variables, and aircraft observations for detailed measurements
of the marine boundary layer.
- Labrador Sea Water (LSW)
- A water mass which forms in the
Labrador Sea via deep convection
in the winter months in a strong cyclonic circulation gyre.
It is a large volume of nearly
homogeneous water with temperatures ranging from
3.0 to 3.6 C, salinities from 34.86 to 34.96, and
consistently high dissolved oxygen content (above 275 mol).
It is formed by the final modification of
Subpolar Mode Water (SPMW) in
the Labrador Sea and contributes to the formation and modification
of various types of North Atlantic deep waters.
Observations indicate considerable interannual variable in
the formation process, with no water being formed at all
in an estimated 4 out of 10 years. This variability leads to
significant interannual variations in LSW properties.
LSW mixes with ABW and eventually
becomes part of NADW, although the
abovementioned variability is not wholly passed on to NADW.
The ABW/LSW mixture recirculates around the Labrador Sea
an estimated 2 to 3 times over 12 to 18 months, a process
which serves to smooth out interannual fluctuations
and results in NADW receiving water with
about half the original variation in magnitude of LSW.
See Clarke and Gascard (1983),
Talley and McCartney (1982a)
Tomczak and Godfrey (1994) and
Paillet et al. (1998).
- Of or pertaining to a lake or
lakes, or of plants and animals growing in or inhabiting lakes.
- Abbreviation for Line-Acoustic Dopper Current Profiler.
- Lafond's tables
- A set of tables compiled by E. C. Lafond for the purpose of
correcting reversing thermometers
dynamic height anomalies. These were published by the
U.S. Navy Hydrographic Office as H. O. Pub. No. 617.
- Lagrangian velocity
- That velocity that would be measured by tracking a dyed
particle in a fluid. Compare to
Eulerian velocity and
- Lake Baikal
- See Kipfer et al. (2000).
- Lake Ontario
- See Pickett (1977).
- Lakshadweep Sea
- See Shenoi et al. (1999).
- Lamb wave
- To be completed.
- Acronym for Long-Term Autonomous Microstructure Profiler, an
instrument designed to autonomously collect microstructure profiles
over deployments of several months duration.
It consists of an autonomously profiling
ALACE float outfitted with two
microtemperature probes and a hard disk for data recording.
The prototype was deployed in the eastern subtropical North Atlantic
in the area of the NATRE study.
See Sherman and Davis (1995).
- Langmuir circulation
- A marine boundary layer phenomena in which wind shear tends to organize
convective perturbations into adjacent, counterrotating roll vortices.
The surface signature of this Langmuir circulation is wind-rows, i.e.
parallel bands of foam, seaweed and slick water that have undoubtedly
been familiar to sailors since long ago.
The first systematic observations were performed by
Langmuir (1938) after whom the phenomenon was eventually named.
He studied it in the surface layers of Lake George, New York using
sophisticated tracers like leaves, corks, and submerged umbrellas
buoyed with light bulbs.
Langmuir circulations tend to carry water with near surface properties
down to below the surface convergence zones, with plankton, seaweeds,
surface detritus, and dissolved gases tending to be concentrated in
the sinking currents. Conversely, water with different temperature
and salinity properties and which is also usually richer in nutrients
is brought toward the surface.
See Langmuir (1938),
Weller and Price (1988) and
Kraus and Businger (1994).
- La Perouse Strait
- See Okhotsk Sea.
- Laplace's tidal equations
- The equations developed by Laplace in 1775-1776 for his dynamic theory
of tides. They were obtained from the continuum equations of momentum
and mass conservation written in rotating coordinates for a fluid shell
surrounding a nearly spherical planet. Assumptions central to their
derivation were a perfect homogeneous fluid, small disturbances
relative to a state of uniform rotation, a spherical earth,
a geocentric gravitational field uniform horizontally and in
time, a rigid ocean bottom, and a shallow ocean where both the
horizontal component of the Coriolis acceleration and the vertical
component of particle acceleration are neglected. The equations
are longitude and latitude with corresponding
velocity components , the ocean surface elevation,
the tide-generating potential, the variable depth of
the ocean, the earth's radius, the gravitational acceleration
at the earth's surface, and the earth's angular rate of
These equations were eventually found to not be uniformly valid,
a problem that was eventually fixed by relaxing the assumption of
homogeneous fluid to allow stratification and developing a similar
equation set called the
long wave equations.
Both sets are used to investigate such long ocean waves as
Kelvin waves and the like, although
these are more commonly and easily studied using an equation set
written in cartesian coordinates on a
beta plane or
an f-plane. For example,
the LTEs simplified for long waves in a uniformly rotating
flat-bottomed ocean, i.e. an f-plane, are
where , equal to , is the
See Lamb (1932), sect. 213-221 and
- Acronym for
Large Aggregate Profiling System.
- lapse rate
- The rate of decrease of temperature with height. This can
be either an environmental or a process lapse rate.
An environmental lapse rate is a static measure of the
state of the environment, e.g. finding the rate of temperature
decrease by measuring the vertical temperature profile in some way.
A process lapse rate, on the other hand, gives the temperature
associated with some action or process, e.g. a rising or sinking
- Laptev Sea
- One of the seas found on the Siberian shelf in the
Arctic Mediterranean Sea.
It sits between the Kara Sea
to the west, the East Siberian Sea
to the east, and adjoins the
Arctic Ocean proper to the north.
The western boundary begins at the Arctic Cape (Komsomolets Island),
proceeds along the eastern shores of the Northern Land, through
the Red Army Strait, along the eastern shore of October Revolution
Island, to the Anuchin Cape and through Shokal'sky Strait to
Bol'shevik Island, along the coast to the Vaigach Cape, along the eastern
boundary of Vil'kitsky Strait to the head of Khatanga Bay.
The northern boundary starts at the Arktichesky Cape, and passes through the
crossing point of the meridian of the northern tip of Lotel'ny Island
(139E) and the edge of the continental shelf
(79 N, 139 00' E).
The eastern boundary begins at the western side of Sannikov Straita, passes
around the western shores of the Large and Small Syakhovsky Islands, and
then along the western extent of Dmitry Laptev Strait.
The southern boundary is the continental shore from Svyatoy Nos Cape
to the head of Khatanga Bay.
The width along parallel 75 N is 717 km, and the length from
Cheluskin Cape to Dimitry Laptev Strait is 1126 km.
The area is around 540,000 km with about 66% being
less than 100 m deep.
The southern and southeastern areas, comprising 45% of the total, have
water depths ranging from 10 to 50 m.
Depths in excess of 2000 m are found in the northern parts.
An incline starting at 100 m and ending at 3000 m divides the sea into
the northern and southern parts along the parallel of the Vil'kitsky Strait.
This has also been called the
Zenkevitch (1963) gives the history of the exploration of
the Laptev Sea to 1955:
Nordenskjöld's expedition on the Vega (1878-1879) marked
the beginning of the exploration of the fauna and flora of the
Laptev Sea, which was continued by the Russian expeditions
of Toll on the Zarya (1900-1903) and Vilkitsky on
hte Taimyr and Vaigach (1913). In the Soviet era the
Norwegian expeditions on the ship Mod (1918-1920 and 1921-1924),
and the Soviet expeditions of Khmisnikov (1926) and of Yu. Tchirikhin
(1927) on the icebreakers Lithke (1934) and Sadko (1937)
have worked in the Laptev Sea.
The runoff into the Laptev Sea from the five major rivers - the
Khatanga, Anabar, Lena, Olenek and Yana) is about 767 km yr.
This runoff, shelf water exchange with the Arctic Ocean, and
perennial ice cover are the main factors determining the water masses.
In the upper Laptev Sea, Arctic surface water (-1.80 C, 32.00)
and Laptev Sea surface water (-1.40 C, 22.00-25.00)
Sea surface water dominate and show only weak seasonality.
Warm Atlantic water (2.25 C, 34.98)
is spread in the north in the deep water troughs
under the Arctic surface water. Below 800-1000 m is cold bottom
water with a temperature of 0.4-0.9 C and a salinity of
34.90-34.95. This water is formed by the sinking of cooled water from
the continental slopes.
The temperature and salinity fields show large gradients between the
mixing zones of river and sea water and the uniform thermohaline
structure in the north. The thermohaline structure is relatively
homogenous in the winter due to a decrease in runoff, increase
in ice cover, and decrease in convection.
The currents are influenced by the position and intensity of the
Icelandic Low and the Arctic High, water exchange with the Arctic
Basin and with the Kara and East Siberian Seas, and by river freshwater input.
A well-defined cyclonic circulation exists in the surface layer of
the Laptev Sea.
A current from west to east along the mainland coast is intensified
by the Lena Current. As it approaches the New Siberian Islands,
it is directed to the northwest and then the north in the form of
the New Siberian Current, finally merging with the Trans-Arctic Current
moving from east to west. Near the Northern Land the waters in the
southern part of the Trans-Arctic Current are generally headed southward and,
in the form of the East-Taimyrskoye Current, reach the coast eastern
flow to complete the cyclonic gyre. Part of the New Siberian current
moves eastward through the Sannikov Strait into the East Siberian Sea.
The current velocities are small, usually not exceeding 10 cm/s.
During the times when the Icelandic Low dominates the Arctic High, there
is a well-developed transport of water masses from south to north,
and the center of the cyclonic gyre shifts toward the Northern Land.
A wind-driven gyre exists in the southeastern region. It is
cyclonic when western atmospheric transports prevail over the eastern
Laptev Sea, and anticyclonic when eastern transports dominate.
The Laptev Sea is covered by ice of different thickness and age
categories from October to May. Formation begins in late September,
with extensive fast ice up to 2 m thick formed in winter in water
depths of less than 20-25 m.
A significant area of polynyas and young ice is preserved to the
north of this fast ice zone. The width of the zone varies from
10 to several hundred kilometers, with the ice edge changing its
position in summer according to wind and currents.
See Zenkevitch (1963),
Fairbridge (1966) and
- Large Aggregate Profiling System (LAPS)
- A system for counting the number and size distribution of particles
in sea water ranging from 250 microns to several millimeters in
LAPS consists of a video camera synchronized with a strobe light
which flashes at predetermined intervals as the instrument is
lowered through the water column.
The light is focused so it illuminates only a narrow slab
of water where the video camera records images of the large
particles in the water.
The video images are analyzed using software which counts the
number of particles and determines their maximum and minimum
dimensions if they are not circular, and this data is used to
estimate a volume and mass of the imaged particles.
LAPS is an integral part of the
Particle and Optics Profiling System (POPS).
- large eddy simulation
- A compromise between explicitly simulating everything down to the
smallest scales of motion via direct simulation and simulating only
the mean flow via Reynolds averaging when modeling turbulent flows.
This is accomplished by
first applying a local spatial filter to the equations of
motion. Then the large-scale turbulent motions are explicitly
simulated while a turbulence model represents or parameterizes
the influence of the unresolved small-scale motions that the
filter has separated.
The scale of the filter operation is usually within or close
to the inertial subrange of 3-D turbulence, where it is expected
that the resolved motions will describe the energy-producing
mechanisms and associated fluxes of heat and momentum and the
unresolved subgrid motions the dissipation of the resolved
This technique originated in meteorology and weather prediction
where the aim is to predict the evolution of large-scale eddies
over their lifetimes, i.e. the weather, while parametering the
effects of not well understood processes like moist convection
and radiative transfer.
See Mason (1994).
- A component of the RIDGE initiative whose
goal is to investigate larval dispersal and gene flow in vent
environments and evaluate the potential role of these processes
in generating and maintaining biogeographic patterns along
mid-ocean ridges and across ocean basins.
- latent heat
- The quantity of heat absorbed or emitted, without change of temperature,
during a change of state (from solid to liquid or from liquid to gas)
of a unit mass of a material. It is a hidden heat (i.e. it can't
be sensed by humans) that doesn't occur until phase changes ocur.
An example is the evaporation of liquid water cloud
droplets cooling the air by removing heat and storing it as
latent heat. Phase changes that cool the air are
vaporization (liquid to vapor), melting (solid ice to liquid)
and sublimation (solid to vapor), while phase changes in the
opposite direction that warm the air are condensation (vapor to
liquid), fusion (liquid to solid) and deposition (vapor to ice).
The latent heat is
for fusion or
or sublimation, with the sign depending on the direction of the
- latent heat flux
- The exchange of
heat between a moisture-containing surface and atmosphere resulting mainly
from the evaporation at the surface and the later condensation
within the atmosphere. This is an indirect transfer of heat
associated with the phase transitions of water, between liquid and
vapor at the surface and later between vapor and liquid or solid
phases. See Peixoto and Oort (1992).
- Acronym for Louisiana-Texas Experiment, sponsored by the
MMS of the Department of the Interior.
LATEX was a six-year project with the principal objective of
identifying the key dynamical processes governing the circulation,
transport, and cross-shelf mixing of the waters on the
The program had three components:
- LATEX A - shelf circulation and transport processes (administered
by Texas A&M University);
- LATEX B - Mississippi River plum hydrography (administered by
Louisiana State University); and
- LATEX C - Gulf of Mexico eddy circulation (administered by
Science Applications International Corporation).
- The name given to a hypothetical
northern hemisphere supercontinent consisting of North America,
Europe, and Asia north of Himalayas prior to breaking up into its
separate components. It was formed in the early
Mesozoic by the rifting of Pangaea
along the line of the North Atlantic Ocean and
the Tethys Sea.
The southern hemisphere analogue was called
Gondwanaland and both comprised a
hypothetical single supercontinent called Pangaea before
their splitting up.
- The Precambrian craton
of central eastern Canada. It forms the ancient core of Canada,
the remainder having been accreted via orogeny.
- layer coordinates
- In numerical modeling, a system of vertical coordinates where
an arbitrary number of layers are specified in which some
fluid property (e.g. density) remains constant, i.e. an
independent variable. The
dependent variable is the
vertical extent of each layer.
Pressure coordinates are
an example of layer coordinates.
Compare to level coordinates.
- layer method
- See core layer method.
- In physical oceanography, this is a consequence of the
double diffusion phenomena.
If a layer of colder, fresher water overlies a layer of warmer,
saltier water, the differences in molecular diffusivities between
salt and heat will cause the water just above/below the interface
to become lighter/heavier than that above/below it and thus it
will tend to rise/sink. The phenomenon, called layering, can
lead to fairly homogeneous layers separated by thinner regions
with large gradients.
- Abbreviation for low cost drifter.
- Abbreviation for Lamont Doherty Earth Observatory, a research
division of Columbia University dedicated to understanding how
planet Earth works. See the
LDEO Web site.
- An opening in pack ice which forms as the result of a local
divergence in its drift. These occur at weak points in the
ice and are characteristically long, narrow channels meters to
hundreds of meters wide and kilometers to tens of kilometers
long. They have no fixed location, although their occurrence
may be predictable by region or season, and the are more
prevalent in regions of thinner ice and marginal ice zones.
Leads typically cover at least 1% of the total ice area, with the
average distance between them varying from 5 km in the marginal
ice zone to 275 in the central Arctic pack ice.
See SMith et al. (1990).
- Acronym for Lead Experiment, a 1992 experiment to study the effect of
leads (cracks in the ice) on the polar ocean and atmosphere.
See Persson et al. (1997).
- Baroclinic eddies composed of LIW as
hypothesized by Millot (1999).
These are posited to form as the LIW becomes unsable as it passes
the open southwest corner of the Sardinian slope.
They propagate into the interior of the Algerian Basin and contribute
to the occurrence of recent LIW there.
- Leeuwin Current
- The eastern boundary current
along the west coast of Australia. This differs from other eastern
boundary currents in that an abnormally large pressure gradient
overrides the usual scenario of equatorward winds producing
surface upwelling, an equatorward surface flow, and a poleward
undercurrent. The Leeuwin Current flows strongly poleward against
equatorward winds due to a difference in
dynamic height of 0.5 m along
the coast. This difference is related the the throughflow
from the Pacific to the Indian Ocean through the
Australasian Mediterranean Sea which serves to maintain the same steric
height on either side of the throughflow. The same height cannot
be maintained by the colder waters off southwest Australia and thus the
lower steric height.
The result is a self-perpetuating
process where the southward flow of warm water leads to surface
cooling which keeps the steric height lower which leads to southward
The annual mean transport of the Leeuwin Current has been estimated
at 5 Sv with average current velocities ranging from
0.1-0.2 m/s, although its intensity and southward extent vary
seasonally. It is strongest in May when the countering wind
is weakest with speeds up to 1.5 m/s. The strong fronts on
both sides of the current tend to produce eddies during this
See Godfrey and Weaver (1991),
Holloway (1995) and
Batteen and Huang (1998).
- length scales
- A thorough investigation of the length scale relationships in the
steady linear theory of rotating stratified fluids can be found
in Blumsack (1973).
- Acronym for Long-Term and Expanded Program of Oceanic Exploration
and Research, an IOC project.
- In the modeling of fluid turbulence, this is an abbreviation for
Large Eddy Simulation, a technique in which eddies above a certain
size are directly simulated and the effects of those of smaller
size are parameterized in terms of some variable at the larger
- An easterly wind in the Straits of Gibraltar, most frequent from
July to October and in March. It is usually associated with
high pressure over western Europe and low pressure to the
southwest of Gibraltar over the Atlantic or to the south
- Levantine Intermediate Water (LIW)
- The saltiest
water mass that forms in the
eastern Mediterranan Sea.
It is exclusively formed in several areas of the
Levantine Basin and the southern
Aegean Sea in February and
March under the influence of dry and cold continental air masses.
Mesocale processes play an important role in the formation and spreading
After its formation, it forms a layer identified by a salinity
maximum between the overlying
Modified Atlantic Water (MAW) and the underlying
Eastern Mediterranean Deep Water (EMDW).
The core depth fluctuates from 50 to 600 m.
The LIW flows eastwards and westwards, with part of the portion
formed in the Levantine Basin
entering the Aegean through the eastern straits of the Cretan Arc with
core temperature and salinity values at the sill depths of
14.5C and 38.9.
Some of this water is ventilated and transformed by convective
processes to become a slightly denser intermediate
water mass called
Cretan Intermediate Water (CIW).
While the characteristics of the source waters generated at different
regions vary (14.70-16.95C, 38.85-39.15C), mixing
results in homogeneity and the loss of heat and salt as the LIW
The slow spreading and long renewal time give LIW as relatively
low oxygen content of less than 4.5 ml/l.
The winter properties of LIW as it leaves the
39.0 39.2, and 28.9
In the Ionian Sea the properties are
transformed into 14
38.8, and 29.0
See Perkins and Pistek (1990),
Stratford and Williams (1997),
Stergiou et al. (1997) and
Theocharis et al. (1999).
- Levantine Sea
- See Ö (1993) and
Theocharis et al. (1999).
- Levantine Surface Water (LSW)
- A warm and saline
water mass occupying most of the surface
layer of the Eastern Mediterranean Sea during the warm part of the
year. It is the product of intense evaporation, with the salinity
reaching maximum values of around 39.5 by the end of the summer,
especially in the northwest Levantine and southeast Aegean Seas around
See Balopoulos et al. (1999).
- A hot, dry, southernly wind which blows on the southeast coast of
Spain in front of an advancing depression. It frequently carries
much dust and sand, with its approach being signaled by a strip
of brownish cloud on the southern horizon. This corresponds to
the scirocco of North Africa and is
named after the direction from which it blows. It is also known
as the solano.
- level coordinates
- In numerical modeling, a vertical coordinate system in which a
arbitrary number of height or depth levels are specified at which
the changing values of the various
dependent variables are calculated.
Thus the level heights or depths are
- level of known motion
- See reference level.
- level of no motion
- A reference level at
which it is assumed the horizontal velocities are
See Wunsch and Grant (1982),
Killworth (1983) and
Olbers and Willebrand (1984).
- level surface
- See geopotential surface.
- Acronym for Labrador Extreme Wave Height Experiment.
See Beal (1991).
- A writer or compiler of a dictionary or a glossary, i.e.
a (relatively) harmless drudge.
- Abbreviation for
Large Scale Geostrophic model, an ocean circulation model
developed at MPI. It is based on the
primitive equations and designed specifically to model
global scale geostrophic circulation. The nonlinear advection
of momentum is neglected and fast gravity waves are strongly
damped via an implicit time integration scheme that uses a
time step of 30 days. An upstream advection scheme us used
for salinity and temperature transport and vertical convective
mixing is applied when the stratification becomes unstable.
The Arakawa E-grid is used for horizontal discretization
and a small horizontal diffusion specified to alleviate the
inherent mode-splitting problems of this grid scheme. Sea
ice is computed from a heat balance and by advection by ocean
currents with a simplified viscous rheology.
- Abbreviation for Longhurst-Hardy Plankton Recorder.
See Dunn et al. (1993).
- A strong, squally southwesterly wind in the central Mediterranean,
most common in winter.
- Acronym for Line Islands Experiment, a GARP project.
- light compensation depth
- An ocean depth above which the intensity of photosynthetic assimiliation
is greater than losses by respiration, and below which the reverse
situation takes place where phytoplankton can exist only due to the
organic matter that has been previously formed, i.e. due to conversion
to heterotrophic nutrition.
See Kagan (1995).
- Ligurian Sea
- One of the seas that comprise the western basin of the
It is located to the north of Corsica between the
Balearic Sea to the west and the
Tyrrhenian Sea to the east.
See Fairbridge (1966) and Astraldi et al. (1990).
- Liman Current
- A cold current that flows from the
Okhotsk Sea into the
Japan Sea. Part of this current
continues south along the western coast and eventually
North Korea Current.
- Lincoln Sea
- A part of the
Arctic Mediterranean Sea located on the
Greenland-Canadian-Alaskan shelf. It is situated northeastward
of Ellesmere Island and northwest of northern Greenland.
See Newton and Sotirin (1997).
- Characteristic of a system (the climate, etc.) wherein the output
is always proportional to the input. As such, the output from
a linear system can be predicted from knowledge of the
input. An equivalent definition of a linear system is a system
that satisifies the superposition principle, i.e. the combined
effect on the output of two separate and distinct inputs can
be found simply by combining, or superposing, their individual
- Acronym for Laser In-Situ Scattering and Transmissometer, an
instrument manufactored by Sequoia Instruments which measures
the in-situ size distribution of particles from 5 to 250 microns in
diameter in water with sediment loads exceeding
200 /l based on the principle of laser diffraction.
It is usually attached to the POPS
system and together they generate diagrams of the size distribution
of particles and small aggregates in the water column without
disturbing them via collection in water bottles.
Particle aggregates in water bottles tend to fall apart before
they can be measured, making the measurements of optical properties
and settling dynamics obtained that way incorrect.
The LISST measures particle sizes by projecting a laser beam
towards a series of concentric ring-shaped detectors.
The angle at which the laser light is scattered depends on
the particle size, with the smaller/larger particles scattering
light toward the outer/inner detector rings.
The distribution of particle sizes is proportional to the
volume scattering function which is inverted to obtain the
particle concentration and size spectrum.
system converts this information into graphs showing the abundance
of particles of each size.
The original LISST-100 model measures particle size spectra,
while an advanced model called the LISST-ST also measures
in-situ settling velocity distributions.
It does this by trapping a water sample and performing a series
of measurements of the type described above over time.
See the Sequoia Instruments Web site.
- Little Climatic Optimum
- A period of time lasting from AD 750 to 1200 when the climate of
Europe and North America was clement, even as far north as
Greenland and Iceland.
See Lamb (1985), p. 435-449.
- Little Ice Age
- A return to colder
climatic conditions beginning in about 1450 and ending around 1890.
This was an era of moderate, renewed glaciation that followed the
warmest known part of the Holocene.
It was marked by the advance of valley glaciers in the Alps, Alaska,
Swedish Lapland and New Zealand far beyond their present limits
as well as by snow on the high mountains of Ethiopia where it is now
evidence points to two main cold stages, each lasting about a
century, during the seventeenth and nineteenth centuries.
Regional timings of the cold periods differed and thus some doubts
have been raised as to the global nature of this phenomenon.
See Grove (1988) for a book-length treatment of this period.
- Abbreviation for
Levantine Intermediate Water.
- Acronym for Levantine Intermediate Water Experiment, which took place
during winter-spring 1995 in the Levantine Basin to study the formation
and spreading of
Levantine Intermediate Water (LIW).
- Abbreviation for
lower low water interval.