- Abbrevation for Satellite Active Archive, a digital library of
real-time and historical satellite data from NOAA's
POES. SAA allows users to search inventories of
satellite data, preview representative Earth images of that data,
and to download the data for further processing and analysis.
- Acronym for the South Atlantic Accelerated Research Initiative, an
ONR research program primarily directed toward improvement of the
description of the subtropical South Atlantic. It focused on
the poleward corners of the subtropical gyre, i.e. the separation
of the Brazil Current and its
confluence with the Malvinas
or Falkland Current in
the southwest, and the
and Benguela Current in the
See Gordon (1988).
- Acronym for South Atlantic Bight Recruitment Experiment, a NOAA
program to stud the birthdate history of survivors (larvae,
late larvae, and juveniles) to determine which life history
phase or passage (spawning, transport across the shelf, inlet
ingress, estuarine development, inlet egress) regulates
recruitment variability in annual cohorts of transgressive
species like Atlantic menhaden.
- Acronym for South Atlantic Bight Synoptic Offshore Observational
Network, a NOPP funded program to develop a real-time observational
network on the continental shelf offshore of South Carolina and
The network consists of eight large offshore platforms - currently operated
by the U.S. Navy for flight training - being instrumented to provide
a range of oceanographic and meteorological observations on a
continuous, real-time basis.
The grid covers an area of 155 km by 50 km and a depth range from
25 to 45 m, with an existing communcations system allowing high bandwidth,
real-time data transmission to shore.
- Acronym for Shipboard ADCP Center, now renamed
- Abbreviation for the
Southern ACC Front.
- Acronym for the South African Data Centre for Oceanography, a center
that stores, retrieves and manipulates multi-disciplinary marine
information from the areas around Southern Africa.
- Abbreviation for Salinity-ADCP.
- Abbreviation for
- Acronym for the Sub-Antarctic Flux and Dynamics Experiment, a program
designed to collect observations of the
ACC south of Tasmania that would permit direct
evaluation of the momentum, energy and vorticity budgets.
The experiment lasted two years - from April 1995 to March 1997 - and
collected multi-year observations of currents and temperatures in both
a small current meter mooring array with a diameter of about 70 km, and
along a SSW-NNE section perpendicular to the expected mean axis of
the ACC at the
The measured variables were found to be coherent horizontally and
vertically in broad, sub-inertial frequency bands, a rarity with
such oceanic measurements.
The center of the SAFDE array consisted of nine subsurface, nearly full
depth moorings deployed as a local dynamics array (LDA), of which four
were fully and three partially recovered.
The array also included a suite of 17 (15 recovered)
horizontal electrometers (HEM) and
18 (all recovered)
inverted echo sounders (IES) to obtain
time series of the vertically
averaged horizontal water velocity, the temperature structure, and
the dynamic height structure.
The HEMs measure the horizontal electic fields which are theoretically
related to the conductivity-weighted, vertically-averaged
horizontal water velocity Chave and Luther (1990).
- Abbreviation for Sir Alister Hardy Foundation for Ocean Science, whose
mission is to further the understanding of marine pelagic ecosystem
It was originally established in 1990 to operate the CPR survey, a program
started in 1931 by Alister Hardy.
- the maintenance and expansion of the Continuous
Plankton Recorder (CPR) survey;
- cooperation in the establishment of
global long-term oceanic plankton monitoring programs;
development of new sampling and sensor systems; and
- the dissemination
of the results of original research.
- saline contraction 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
McDougall (1987b) gives a polynomial expression
The units of are psu and the rms error of this fit
psu. A test value is
psu at = 40 psu,
= 10.0C and = 4000.0 db.
See McDougall et al. (1987) and the related
thermal expansion coefficient
and adiabatic compressibility.
- An oceanographic concept conceived to provide a measure of the
mass of salt per unit mass of seawater.
The first systematic attempt to define this was made by
a commission appointed by the International Council for the
Exploration of the Sea in 1899 and chaired by Knudsen.
Attempts to measure salt content by drying samples were
accompanied by losses of volatile compounds along with
the water, and the hygroscopic nature of the residue also
served to complicate matters. A dry residue method where the
sample was evaporated and dried to a stable weight at
480 C after processing with hydrochloric acid was
offered as an alternative method. This led to the definition of
the salinity as ``the total amount of solid material in grams
contained in one kilogram of seawater when all the carbonate
has been converted to oxide, all the bromine and iodine replaced
by chlorine, and all the organic material oxidized.''
When this dry residue method also provided practical difficulties
aboard ship the commission defined a
chlorinity that could be determined
via a volumetric titration using silver nitrate. This measurement
could be combined with the assumption of constant ionic ratios
in seawater to obtain a measure of the salinity, with the
relationship between the two quantities being defined as
A small adjustment was made in the definition of chlorinity in
the late 1920s, but it remained basically the same until
the development of reliable and precise electronic instrumentation
in the 1950s led to a qualitative redefinition of the chlorinity,
and therefore the salinity, in terms of measurements of the
electrical conductivity of a water sample. This led to the
creation and publication of the the International Oceanographic
Tables giving salinity as a function of conductivity ratio
above 10. These tables were adequate for the laboratory
determination of salinity, but could not be used with in-situ
salinometers since most such measurements were made at temperatures
below 10 C. A separate set of tables were developed
in the mid-1960s that covered the range 0-30 C, although
this led to discrepancies between in-situ and bench measurements
of salinities and many separate attempts to patch together the
two data sets. This in turn led to confusion in the comparison
of salinity data amongst the major oceanographic institutes.
A solution was found
in 1978 in the form of a new definition called the
Practical Salinity Scale (PSS-78)
where the practical salinity is defined in terms of the ratio
of the electrical conductivity of a seawater sample at
atmospheric pressure at 15C to that of KCl solution
containing 32.4356 g of KCl in a mass of 1 kg of solution at the
same pressure and temperature.
See Lewis (1980) and Lewis and Perkin (1978).
- Abbreviation for saturated adiabatic lapse rate.
- salt fingering
- See double diffusive instability.
- salt fountain
- A hypothesized perpetual fountain where a long, narrow heat-conducting
pipe inserted vertically through a region of ocean where warm, salty
water overlies colder, fresher (and therefore denser) water. Water
pumped upwards through the pipe would reach the same temperature as
the surroundings at the same level (by conduction of heat through the
wall of the pipe), while it remained fresher and therefore lighter.
A fountain started thusly (in either direction) will continue to flow
so long as there is a vertical gradient of salinity to supply
potential energy. The idea was first advanced by
Stommel et al. (1956) and is discussed in
- Samar Sea
- A small sea contained within the Visayan Islands that comprise
the central portion of the Philippines.
It is centered at approximately 124 E and
12 N and connected to the
Visayan Sea to the southwest,
the Philippine Sea to
the northeast via the San Bernardino Strait, and
the Sibuyan Sea to the northwest.
- Acronym for Sub-Antarctic Motions in the Brazil Basin, a
component of the WOCE float program aimed
at describing the absolute general circulation of the
Antarctic Intermediate Water (AAIW)
as it spreads northward at about 800 m depth in the Brazil Basin.
During the SAMBA experiment a total of 100
MARVOR floats were launched
between February 1994 and December 1998 at 800 30 dbar in the
- In signal processing, to pick out values from an analog
signal, usually at regular intervals, to create a
corresponding digital signal.
- Abbreviation for
Subantarctic Mode Water.
- More later.
- Sandstrom's Theorem
- An ocean circulation theorem that states that a closed steady
circulation can only be maintained in the ocean if the heat
source is situated at a lower level than the cold source.
Sandstrom considered to momentum balance of the steady circulation of
the oceans, and concluded that, to overcome friction, there should be
a net input of mechanical energy over each closed streamline, i.e.
where and are the specific volume and pressure, and the integration
is taken along closed streamlines .
He modeled the oceanic circulation in terms of a heat engine by assuming four
idealized stages within each cycle of the oceanic heat engine:
Within this cycle, the net amount of work would be negative if the system is
heated under low pressure, and cooled under high pressure. Positive work
is only possible when heating takes place at a higher pressure and cooling
at a lower pressure.
- heating-induced expansion under a constant pressure;
- adiabatic transition from the heating source to the cooling source;
- cooling-induced contraction under a constant pressure; and
- adiabatic transition from the cooling source to the heating source.
The application of this theorem to the ocean was a vexing issue for
years, as is summarized by Huang (1999):
However, the application of Sandstrom's theorem to the oceanic circulation
does pose a serious puzzle. The ocean is mostly heated and cooled from
the upper surface. Due to thermal expansion, the sea surface level at
low latitudes where heating takes place is about one meter higher than
the sea level at high latitudes where cooling takes place. Therefore,
according the Sandstrom's theorem, there should be no convectively
According to Huang (1999), the resolution lies in Sandstrom's original
model excluding diffusion and friction.
He used an idealized loop model of the oceanic thermohaline circulation that
included mixing to discover that the circulation can be classified into two
types, depending on the vertical locations of the heating and cooling
An unexpected result from the same study was that geothermal heating
can contribute a substantial portion of the energy for the mixing
of deep water.
Another interesting result was finding
the diapycnal mixing rate due to tidal energy and geothermal heat flux
to be about 0.22-0.28
See Defant (1961) and
- When the cooling source is at a level lower than the heating source,
the circulation is mixing controlled and the rate of thermal circulation
is primarily controlled by the amount of external energy available for
mixing. Without the external energy the support mixing, the mixing rate
would be at a very low level determined by molecular diffusion, and there
would be no detectable thermal circulation as per Sandstrom's theorem.
With an external energy source, e.g. wind stress, tidal dissipation, etc.,
there can be a strong thermal circulation even if the cooling source is
below the heating source.
- If the cooling source is at a level higher than the heating source,
the circulation is friction controlled, and the amount of external energy
available for mixing is unimportant.
- San Matías Gulf
- A gulf located at around 42S along the Argentine coast of
eastern South America.
According to Piccolo (1998):
It has a significant interaction with the adjacent shelf.
A sill at a depth of 74 m is found at the entrance of the
gulf. It is a basin with 200-m depths at its center.
Unfortunately, very few studies were performed to learn its
circulation and dynamics, and therefore only a brief review is presented
here. The temperature structure of the gulf in winter reveals a
well-mixed water column indicative of deep-reaching and
bottom water ventilation. Near 4150'S a relatively
intense thermohaline front is found.
Relatively cold fresh waters similar to the open shelf waters
are found south of the front, while warm salty waters typical of
the gulf are found north of the front.
This front is produced by tidal mixing.
The gulf circulation is dominated by a cyclonic gyre about 70 km
in diameter located north of the front.
South of the front the thermocline structure is complex and not
well resolved by the observations. The San José Gulf communicates
with the San Matías Gulf, and there is a strong water interaction
between both coastal bodies.
See Piccolo (1998).
- Santa Barbara Channel
- See Harms and Winant (1998).
- Abbreviation for Synthetic Aperture Radar, a side-looking imaging
radar system that uses the Doppler effect to sharpen the effective
resolution in the cross-track direction. Basically, high resolution
is achieved by measuring the travel time of short emitted pulses,
while comparable resolution is achieved in the azimuthal (flight)
direction by collecting the amplitude and phase histories of the
returned signals from a large number of individual pulses
to reconstruct the signal of a large virtual antenna. An
SAR on a polar orbiting satellite at 800 km can typically
scan a swath about 100 km wide with a resolution of 20 m by
20 m at incidence angles of 20 to 25.
Incident electromagnetic microwaves resonantly interact with
short ocean ripple waves and backscatter via the mechanism
of Bragg scattering.
An SAR system is capable of detecting a variety of large scale
oceanic phenomena which modulate the short (Bragg) ocean ripple
spectrum, e.g. fronts, internal waves, natural surface films or
man-made slicks, bottom topography, and ocean gravity waves.
These modulations may be of either the
tilt moduluation or
See Komen et al. (1996).
- Sargasso Sea
- A clockwise-circulating
region in the North Atlantic Ocean bound by the
Gulf Stream on the west and
north and less definitely to the east at 40 W near the
Canary Current and to the
south at 20 N near the
North Equatorial Drift Current.
It is so named because of the indigenous,
yellow-brown seaweed called
Sargassum that is found there in
great abundance. The Sargasso is part of the
circulation system in the North Atlantic and comprises a large
part of its interior circulation, covering an area of around
5.2 million square kilometers.
A large volume of a type of mode water
known as 18 water forms in the
Sargasso in the winter and is seen as a thick layer of water
at that temperature between 250 and 400 m depth.
In the summer an excess of evaporation over precipitation
results in a thick (nearly 900 m deep near the center) lens of
water warmer and more saline than surrounding waters. The
anticyclonic sense of the circulation causes this water to pile up such
that it is almost a meter higher than the sea level along the
eastern U.S. coast. This water lens also serves to inhibit the
upwelling of nutrient-rich, colder water which results in a sparsity
of marine life in the region. It is has been called the clearest,
purest and biologically poorest ocean water ever studied.
The northwestern part of the Sargasso is a region of
recirculation for the Gulf Stream.
This recirculation region is dominated by cold core eddies
pinched off from the Gulf Stream, with as many as 10
clearly identifiable rings
found there at any one time. This makes this northwestern region one of the
most energetic in the world ocean.
- Sargasso Sea Water (SSW)
- See 18 Water.
- The name given to about eight species of seaweed that float in clumps
and long windrows in the
It was so named by Portuguese sailors who followed the voyages
of Columbus through the region and noticed the resemblance of
the small air bladders that allow Sargassum to float to a type
of grape called Salgazo.
- Acronym for the SEASAT-A Scatterometer
System, an active backscatter scatterometer operating at
a frequency of 13.0 GHz which produced earth locatino and
time tagged backscatter coefficients, surface wind stress, and
surface wind vectors (with a 180 degree directional ambiguity).
- satellite altimetry
- See Fu. and Cazanave (2001).
- satellite oceanography
- More later.
- saturated adiabatic lapse rate
- The temperature lapse rate of air
which is undergoing a reversible natural adiabatic process.
- saturated humidity mixing ratio
- The humidity mixing ratio of air which is saturated at a specified
temperature and pressure, with saturation defined with reference
to either liquid water or ice.
- saturation mixing ratio
- An atmospheric quantity given by
where is the ratio, the
saturation vapor pressure
and the atmosphere pressure.
- saturation vapor pressure
- Usually measured with respect to water, this is the maximum
water vapor pressure that can
occur when the water vapor is in contact with a free water
surface at a particular temperature. It is the water vapor
pressure that exists when effective evaporation ceases.
- Abbreviation for
Subantarctic Upper Water.
- Acronym for South Atlantic Ventilation Experiment, an experiment
taking place from 1987-1989.
- Savonius rotor
- A rotor originally developed for power generation (i.e. it's a
propellor in reverse that spins when placed in moving water) that
has been extensively used as a sensor on various ocean current
meters. Its advantages are that it is rugged, omni-directional and
linear in steady flow, but its response to time-varying flow and
susceptibility to contamination by vertical flows make it unsuitable
for measurements near the surface where wave action creates both
time-varying and vertical flow fields.
See Heinmuller (1983).
- Savu Sea
- See Sawu Sea.
- Sawu Sea
- One of the several connected seas that comprise the
Australasian Mediterranean Sea. This is centered at
approximately 123 E and 9 S and is situated
between Timor to the south and east, Sumba to the south and
west, and Flores to the north. The basin is mostly greater
than 1500 m deep and reaches depths greater than 3000 m over
most of its northern and eastern parts.
- Abbreviation for Synthetic Aperture Radar and X Band Ocean
Nonlinearities-Forschungsplatform Nordsee program, a 3-year
effort to investigate radar backscatter from the ocean and
synthetic aperture radar (SAR) imagery of the ocean.
A secondary objective was to explore the relationship between
acoustic and microwave scattering from the ocean surface.
This joint U.S./Federal Republic of Germany
program consisted of Phase I, a major field experiment
in the North Sea on and around the German Forschungsplatform
Nordsee during November 1990, Phase II, a second and smaller
field experiment on the same platform in November 1991, and
a series of four data analysis workshops.
See Plant and Alpers (1994).
- Abbreviation for
- scale depth
- A means of characterizing a (oceanic or atmospheric) density
field. It is defined by
where is the
speed of sound and
In the ocean this is on the order of 200 km. The largeness of this
in comparison to the water depth (5 km) is one of the key assumptions
in the Boussinesq approximation.
- scale height
- In the atmosphere, the height at which the pressure has fallen to
e-folding scale) of its value at
the surface. This occurs at about 370 mb which, for a temperature
of 250 K, is about 7.4 km.
- The process by which some of a stream of radiation is dispersed to
travel in directions other than that which from it was incident by
particles suspended in the medium through which it is travelling.
- A high-frequency radar instrument that transmits pulses of energy
towards the ocean and measures the backscatter from the ocean
surface. It detects wind speed and direction over the oceans
by analyzing the backscatter from the small wind-induced
ripples on the surface of the water. See the
NASA JPL scatterometer site.
- Acronym for the Sound Channel Axis Velocity Experiment, where
SOFAR explosive charges were fired at the depth of the
sound axis off Antigua and the resulting signals received
and processed at Eleuthera and Bermuda. In this experiment,
taking place in 1961, travel times were ascertained to
within 30 ms with rms variations estimated at at 200 ms over
a period of 27 months with time scales of a few months.
The variations were most likely caused by the mesoscale
variability that characterizes this region.
See Munk et al. (1995).
- Acronym for Surface Current and Wave Variability Experiment, an
EC MAST project whose primary objective is to measure the spatial
and temporal variability of waves and currents in coastal regions
using the full range of state of the art measurement techniques and
The measurement systems used in this experiment include HF radar,
synthetic aperture radar (SAR), satellite altimetry, accelerometers,
ADCP, current meters, pressure cells, and X-band ground-based radar
since one of the primary goals is the intercomparison of these
- Schlutsky-Yule effect
- A consequence of smoothing a time series with a low-pass filter.
In a relatively short time series, even purely random fluctuations
can give the impression of there being significant quasi-cyclic
fluctuations present if they are smoothed by some sort of
running mean. This is name for two statisticians who demonstrated
in 1927 that some trade cycles that had been apparently discovered
in some 19th century data could be reproduced from a series of
See Burroughs (1992), p. 20.
- Schmidt number
- A nondimensional number that relates the competing effects of
gas diffusion and fluid viscosity on the
piston velocity, a key variable
in measuring gas transfer across the air-sea interface.
The Schmidt number is given by
where is the kinematic viscosity and
the molecular diffusivity of gas in sea water.
See Najjar (1991).
- A 5-year program (1995-1999) in which the U.S. Navy made available
a Sturgeon-class, nuclear powered attack submarine for unclassified
science cruises in the Arctic Ocean.
A test cruise in 1993 started a collaboration between civilian
scientists and Navy personnel wherein a variety of information
on the geology, physics, chemistry and biology of the Arctic
was gathered. The 100,000 miles of shiptrack traveled during the
program allowed data to be gathered from regions that have never
before (at least officially) been visited.
- A warm, southerly wind in the Mediterranean region. Near the north
coast of Africa the wind is hot and dry and often carries much
dust. After crossing the Mediterranean, the scirocco reaches the
European coast as a moist wind and is often associated with
- Acronym for San Clemente Ocean Probing Experiment, a NOAA
ETL program conducted in September 1993.
It was an experiment to study the effects of the atmosphere
on active and passive microwave remote sensing measurements of
the ocean surface.
- The South Channel Ocean Productivity Experiment was
a multidisciplinary study of a whale-zooplankton predator-prey system
in the southwestern Gulf of Maine that focused on the oceanographic
factors responsible for the development of dense patches of the
copepod Calanus finmarchicus, the major prey resource for
See Kenney and Wishner (1995).
- Acronym for Scientific Committee on Oceanic Research, the oldest
interdisciplinary committee of the
ICSU, established in 1957 for the
promotion and coordination of international oceanographic activities.
SCOR doesn't directly fund research although its scientific groups
organize international meetings, publich scientific literature,
and propose and plan large international collaborative efforts
such as JGOFS and
SCOR consists of its members - the national committees for oceanic
research of its 39 member countries, each represented by three
An Executive Committee, elected at biennial General Meetings, also
includes ex officio members from allied disciplinary organizations
A SCOR Secretariat located at Johns Hopkins University in Baltimore,
Maryland provides routine administrative support for SCOR activities
as well as publications such as the JGOFS and GLOBEC Report Series,
the annual SCOR Procedings, and the directory or SCOR Handbook.
There are two major categories under which SCOR work can be subsumed.
The first is the traditional mechanism of the SCOR working group
wherein small international groups address narrowly focused scientific
problems that will benefit from such a cooperative effort.
These groups generally have about ten members, meet two or three times,
and produce either a book or special journal volume or organize
an international conference or workshop to complete their efforts.
They are estblished on the basis of proposals received from national
committees, other organizations, or even individual scientists.
While the working group exists for short term (four years or less)
projects, longer term and more complex activities are the province
of the second mechanism, i.e. scientific committees.
The names of the currently (1998) constituted SCOR working groups (along with
their respective numbers) are:
- Ecology of Sea Ice (86),
- Sea Level Rise and Erosion of the World's Coastlines (89),
- Pelagic Biogeography (93),
- Sediment Suspension and Sea Bed Properties (95),
- Acoustic Monitoring of the World Ocean (96),
- Physiological Ecology of Harmful Algal Blooms (97),
- Worldwide Large-scale
Fluctuations of Sardine and Anchovy Populations (98),
- Linked Mass and Energy Fluxes at Ridge Crests (99),
- Sediment Coring for International Global Change Research (100),
- Influence of Sea State on the Atmospheric Drag Coefficient (101),
- Comparative Salinity and Density of the Atlantic and Pacific Ocean
- The Role of Wave Breaking on Upper Ocean Dynamics (103),
- Coral Reefs Responses to Global Change (104),
- The Impact of World Fisheries Harvests on the Stability and Diversity
of Marine Ecosystems (105),
- Relative Sea Level and Muddy Coasts of the World (106),
- Improved Global Bathymetry (107), and
- Double Diffusion (108).
- Scorpio Expedition
- A name of a 1973 expedition, led by Henry Stommel, to perform
trans-Pacific hydrographic sections at 28 and 43 S.
See Stommel et al. (1973).
- Scotia Front (SF)
- A front located north of the
Weddell-Scotia Confluence which
marks the boundary between the Weddell and Scotia Seas in
the Southern Ocean.
The SF is a distinct subsurface front marked by a maximum
thermal gradient in the maximum temperature core layer (200-700 m)
of the Circumpolar Deep Water (CDW).
Crossing the SF from north to south, the temperature maximum
decreases from 1.5-2.0 C to below 0.5,
with the CDW salinity maximum in the 800-1200 m layer similarly
decreasing southward across the SF from 34.70-34.72 to 34.67-34.68.
In the minimum temperature layer, the SF appears as a thermal
front across which the minimum temperature decreases southward
from 0-0.5 C to below -1.0 C.
There is usually no distinct sign of the SF in the surface
The 1 isotherm in the 300-500 m layer is considered
a good single indicator of the SF axis.
See Belkin and Gordon (1996).
- Scotia Ridge
- A ridge connecting South American and Antarctica
located at about 70 W in the
Southern Ocean that, along with
the narrowing of the Drake Passage
2000 km to the west,
impedes the flow of the
Antarctic Circumpolar Current (ACC).
It is generally less than 2000 m deep with some openings
at the 3000 m level. After the ACC accelerates to squeeze through the
Drake Passage it hits to Ridge and an increased speed and
- Scotia Sea
- More later.
- Abbreviation for South China Sea Monsoon Experiment, a large-scale
experiment to study the water and energy cycles of the Asian monsoon
regions. The goal is to provide a better understanding of the key
physical processes for the onset, maintenance and variability of the
Southeast Asian monsoon.
- sea breeze
- A wind blowing from the ocean towards land caused by the effects
of differential heating.
In the summer when the land surface is warmer than the ocean,
the air over the land heats up more than over the ocean, expands
and becomes less dense, and rises. This rising air is replaced,
due to the constraints of continuity, with moisture-rich air
from over the oceans.
- Sea Grant
- The idea of a Sea Grant College Program was first suggested by
Athelstan Spilhaus at a meeting
of the American Fisheries Society in 1963.
He predicted the proposed sea-grant colleges would spur advancements
in the ocean sciences that would be ``modernized parallels
of the great developments in agriculture and the mechanical arts which
were occasioned by the Land-Grant Act of about a hundred years ago.''
In 1965, Senator Claiborne Pell of Rhode Island introduced legislation
establishing Sea Grant colleges on campuses nationwide, leading to the
adoption of the National Sea Grant College Act in 1966.
The first four universities to achieve Sea Grant College status were
Oregon State, Texas A&M, the University of Rhode Island and the
University of Washington in 1971. As of 2001, there are 30 Sea Grant
Colleges divided into Great Lakes, Northeast, Mid-Atlantic,
Southeastern Atlantic and Gulf of Mexico, and Pacific Regions.
- sea ice
- More later.
- sea level
- Much more later.
- sea level change
- Recent analyses indicate that the global or eustatic sea level has risen
about 2 mm per year over the last century, with the rate probably being
much smaller for the previous several millennia.
The rate is predicted to be larger over the
next century - although how much larger is still uncertain.
Quantifying sea level change is a difficult
task given the complexity of the contributing processes including:
See Douglas (1995).
- the regional submergence or emergence of tide gauges due to
Post Glacial Rebound (PGR) that continues from the last deglaciation,
as well as to other tectonically-induced vertical crustal movements;
- the thermal expansion and contraction of the ocean due to climate
change, along with possible accompanying changes in circulation and
necessarily water levels;
- the contribution of the Greenland and Antarctic ice sheets as they
shrink or expand;
- the shrinking or expanding of smaller glaciers; and
- water storage in artificial reservoirs that would otherwise have
flowed into the oceans, e.g. one estimate that storage in above-ground
reservoirs over the last 40 years was equal to a fall of global sea level
of 0.7 mm per year.
- Sea of Azov
- See Azov, Sea of.
- Sea of Candia
- See Cretan Sea.
- Sea of Crete
- See Cretan Sea.
- Sea of Japan
- See Japan Sea.
- Sea of Okhotsk
- See Okhotsk Sea.
- sea state
- More later.
- Acronym for SeaWiFS Bio-Optical Archive and
Storage System, a product of the calibration/validation element
of the SeaWiFS project which provides an interface to the
project holdings of bio-optical and laboratory instrument
- SEA LION
- Acronym for SEa ice in the Antarctic LInked with OceaN-atmosphere
forcing, a project whose aim is to assess and improve the performance
of coupled global atmosphere-sea ice-ocean models in reproducing
sea ice in the high southern latitudes.
- More later.
- Acronym for Study on Sea-Air Exchanges program.
See Riley and Chester (1989).
- Acronym for Study of the European Arctic Shelf, an LESC program.
- Acronym for Shipboard Environmental (Data) Acquisition System, a program
developed by NOAA to provide accurate meteorological
and oceanographic data in real time from ships at sea through the use of
satellite data transmission techniques. The shipboard data is
transmitted to NOAA via either the GOES or INMARSAT C satellites.
- Acronym for Synthetic Aperture Radar for Sea Studies.
- A NASA satellite that operated from June 1978 to October 1978.
Instruments on board included SASS, an
altimeter, SMMR, a microwave
SAR, and VIRR.
The altimeter was an active radar altimeter which produced
earth location and time-tagged satellite heights, significant
wave heights, and geoid information. The SAR produced 25 meter
resolution surface roughness imagery on a 100 km wide ground
- An open ocean undulating data acquisition vehicle originally designed
and built by the Institute of Oceanographic Sciences (now the
Southampton Oceanography Center, UK).
SeaSoar is capable of undulating from the surface to 500 m at tow
speeds of up to 12 knots (with a faired cable) following a controlled
and adjustable undulating path through the ocean.
Data obtained from sensors mounted in SeaSoar are transmitted to
the towing vessel via a multi-core tow cable.
- seasonal thermocline
- In oceanography, a weakly stratified layer of water that appears
when the mixed layer makes a rapid transition between its
winter maximum and its summer mimimum. It is created by deep
convection during the winter, and several processes are
responsible for its restratification during the rest of the
year. These processes, in chronological order starting in
early spring, are the creation of a fossil thermocline
during the ascent of the mixed layer, solar heating below
the mixed layer, geostrophic advection, and thermohaline
- seasonal thermostad
- See seasonal thermocline.
- sea spray
- See Andreas et al. (1995).
- sea surface film
- A microlayer hundreds of microns thick located at the sea-air
interface. These are the site of intense accumulation of organic
matter from underlying waters or atmospheric deposition.
See Romano (1996).
- sea surface slick
- A sea surface film in which organic
accumulation exceeds a threshold such that it becomes visible as a
slick, i.e. a sea surface feature that appears as smooth grey spots or
stripes in contrast to the surrounding deep blue waters.
The smoothing effect is due to the accumulation at the sea-air
interface of organic compounds, many of them surface-active, which
enhance solar reflection at the surface by damping the
Slicks are thought to play a significant role in heat flux and gas
exchange, biogeochemical cycles, and pollutant dispersion
dynamics as a consequence of the organic enrichment and their
location at the boundary between atmosphere and ocean.
See Romano (1996).
- See Fofonoff (1962) and
- Acronym for Sea-viewing Wide-Field of view Sensor, an ocean color sensor
to study ocean productivity and interactions between the ocean ecosystems
and the atmosphere.
For more information see the
SeaWiFs Web site.
- A scatterometer flown aboard the
- Abbreviation for Southeast Bering Sea Carrying Capacity, a
investigation whose goal is to document the role of juvenile
pollock in the eastern Bering Sea
ecosystem, to examine the factors which affect their survival,
and to develop and test annual indices of pre-recruit
- Secchi disk
- A white target lowered
from a vessel and viewed from above the surface in full solar
illumination to estimate the attenuation in the water column.
This is done by empirically relating the depth at which the
disk disappears to the attenuation. This method was devised
in the 1860s by an Italian astronomer named Angelo Secchi who
used it while he worked in the Mediterranean aboard the papal
The Secchi disc is usually 20-30 cm in diameter, and is either all white
or has four quadrants, two painted white and two black.
The empirical relation used is:
where is the Secchi depth,
is the attenuation coefficient for directional light,
is the diffuse attenuation coefficient for non-directional
light (sometimes known as the extinction coefficient),
is a background factor depending on the reflectivity of both the
disc and the background and the observer's threshold perception of contrast,
and is the sighting angle from the horizontal.
Typically, ranges from about 8.7 in clear oceanic water to 6
in turbid estuarine water.
The disc is typically used to estimate the diffuse attenuation
coefficent or the attenuation coefficent .
For the former, it has been found that the product of and
is relatively constant, with measurements in many types of water
An empirical relationship has also been derived for the latter, i.e.
- Abbreviation for
South Equatorial Current.
- Abbreviation for
South Equatorial Countercurrent.
- Acronym for Schematisation des Echanges Hydriques a l'Interface
entre la Biosphere et l'Atmosphere, an LSP.
See Ducoudre et al. (1993).
- Acronym for a research program which translates to Energetically
Active Zones of the Ocean and Climate Variability. This was
a joint program among Poland/USSR/Bulgaria/Germany/Cuba that
gathered the largest data set ever collected in the tropical Atlantic.
The six ships used in the program were the Academic Vernadsky
and the Mikhael Lomonosov from the Marine Hydrophysical Institute
(MHI) of the Ukrainian Academy of Science in Sevastopol and the
Volna, Jakov Gakkel, Dmitry Ushakov, and
Parshin of the State Oceanographic Institute (SOI) of the USSR.
The MHI vessels collected hydrographic data at 5 m vertical intervals
with 65% of the stations extending to 1200 m, while the SOI vessels
collected data at 10 m intervals (although it was archived only at
16 standard levels). The combined data set archived at MHI consists
of 4931 temperature and salinity profiles collected during 26 surveys
carried out from 1984 to 1990.
The surveys were divided into three stages.
The first stage (1984-1985) comprised eight surveys conducted
near the South American coast between 2 S and
20 N, with each survey consisting of 8 to 10 hydrographic
sections perpendicular to the coast. The sections were 100 km
and the stations 50 km apart in a survey designed to define the
seasonal cycle in the northwest.
The second stage (1986-1988) comprised twelve surveys conducted
between 2 S and 12 N latitude and 58 and
5 W longitude. During the first two years of this stage
the sections were 166 km and the stations 55 km apart, with the
between-section spacing increased to 333 km durin the final year.
Two or three vessels were usually simultaneously collecting data
in a survey designed to investigate the seasonal variability of the
North Equatorial Countercurrent (NECC).
The third stage (1989-1990) saw seven surveys organized into three
experiments designed to observe synoptic variability, with one experiment
in the west and one in the central basin. The first experiment took
place in the spring of 1989 with two vessels in the western region;
the second was in the fall of 1989 in the east with two vessels; and
the third took place in the winter of 1990 using two vessels in the
See Chepurin and Carton (1997).
- A program to examine shelf edge exchange processes on the outer margin of
the U.S. Mid Atlantic Bight.
The SEEP program began in 1980 when a group of investigators met
to propose an interdisciplinary, inter-institutional program called
SEEP (Shelf Edge Exchange Processes) to test what was known as
the ``shelf-export hypothesis.''
This was a conjecture that the large fraction of the spring phytoplankton
bloom that was observed to not be consumed by the local pelagic
food web was exported from
the continental shelves to the central ocean basins or to the sediments
of the upper continental slope.
It was predicted that the net export of
particles across the shelf-slope break would increase with successive,
more southerly experiments because of an expected southerly increase
in primary productivity, and also because of a southerly decrease
in the width of the shelf.
A primary problem with the hypothesis was the existence of a strong
temperature-salinity front separating the continental shelf and slope,
the sort of barrier particles would find difficult to cross.
However, iseveral other mechanisms for exporting
particles from the shelf - e.g. entrainment
of shelf water by passing warm core eddies, sinking across the front,
advection by the benthic boundary layer - were identified and thought to
be collectively sufficient for the task. They were also collectively
referred to as ``diffusive'' processes.
SEEP-I took place from July 1983 to October 1984 in the waters of the
Mid-Atlantic Bight (MAB) shelf and slope south of Cape Cod and Long
The field program consisted of two experiments run by two different
groups, with little overlap between them.
This fragmentation of effort led to estimates of particle export ranging
from 10% diffusive exchange across the shelf edge (with some indication
of an increase towards the southwest), to 10-20% with most oxidized on
the shelf, to from 10% to nearly 40% in model results.
This led to the design and implementation of
See Walsh et al. (1988).
- A program to examine shelf edge exchange processes on the outer margin of
the U.S. Mid Atlantic Bight.
This follow-up to SEEP-I took place from
February 1988 to June 1989, during which 10 cruises took place and
10 moorings were placed at 12 locations on the shelf and upper slope south
of the Delmarva Peninsula.
The vanishing likelihood of a SEEP-III led to the moorings being
deployed in two transects parallel to the mean isobaths and 90 km
apart, the latter to attempt to identify the hypothesized
increase in across-shelf particle flux to the south.
SEEP-I was more integrated than SEEP-I, with the instrumentation
from different institutions intercalated throughout the experiment.
The result was perhaps the most extensive set of moored, synoptic
measurements of temperature, salinity, phytoplankton chlorophyll
fluorescence, macrozooplankton, oxygen, current conditions and
verticle particle flux yet acquired in an oceanographic program.
According to Biscaye et al. (1994):
The results of the SEEP-II study overwhelmingly show that the
hypothesis of export of a large proportion of the MAB [Mid-Atlantic Bight]
shelf primary productivity is untenable. All the observational data
suggest that although a small fraction of carbon is exported across the
shelf-slope break and through the front to the slope decpocenter, the
principal fate of shelf carbon is, in fact, oxidation on the shelf.
That small portion that does escape the shelf to the shelf water
and depocenter appears to increase from the northern to the southern
Several key questions remained unresolved, though, including:
See Biscaye et al. (1994).
- the sources of nitrogen for the shelf to support the measured
production are unclear, i.e. it is difficult to reconcile the flux of
nitrate onto the shelf without imposing an export flux of water (or
- the rate of the oxidation of phytoplankton carbon and its fate
do not appear to be that previously proposed for the metazoic metabolism,
i.e. there was not a monotonic increase in phytoplankton phase-lagged
by a monotonic increase of zooplankton;
- food web dynamics in the shelf ecosystem are still not well
understood, e.g. the microbial oxidation of carbon is much more
significant than previously acknowledged; and
- most of the shelf water leaves the shelf before it reaches the
southern terminus of the MAB (i.e. Cape Hatteras), and the amount of slope
water incorporated into the shelf water along the way leads to an
estimate of water discharged into the slope of 125-150% of
the initial alongshelf transport, i.e. it has yet to be quantified
exactly where, how much, and by what mechanisms water leaves or
comes onto the shelf; and
- horizontal as well as vertical gradients of physical and biological
quantities will have to be measured to fully understand their
interactions, and probably on a nested grid due to the range of
time and space scales involved.
- More later.
- seismic sea wave
- Much more later.
- Seismic Sea-Wave Warning System
- A network of seismographs
across the Pacific Ocean to serve as an early warning
system against the arrival of
seismic sea waves (SSW) (also
called tsunamis or, in an egregious misnomer, tidal waves).
The SSWWS was established in 1946 after a particularly
destructive SSW originating at Unimak, Alaska struck Hawaii
and killed 159 people. Its headquarters are in Honolulu,
Hawaii and it is operated by the Coast and Geodetic Survey
of the U.S. Dept. of Commerce.
- An experiment that took place in the northern Canary Basin from
July to November 1993.
A large data set was obtained from three hydrographic arrays,
current meter moorings, surface drifters drogued at 150 m, and
2000 m deep RAFOS floats.
See Eymard (1998).
- Descriptive of a tide that has a cycle of approximately
one-half a tidal day,
as opposed to diurnal.
- semi-geostrophic equations
- See G. and Flierl (1981).
- semi-implicit method
- A numerical approximation algorithm that allows longer time steps
than an explicit method and is less computationally onerous
than a fully implicit method. Algorithms can usually be
designed using this compromise method that both allow the
longer time step and don't sacrifice numerical accuracy.
- sensible heat
- The portion of total heat associated with a temperature change,
as opposed to latent heat. This is
so-called because it can be sensed by humans. The sensible
heat is calculated by
where values are
for dry air,
for moist air (where is the mixing ratio of water vapor), and
for liquid water.
- sensible heat flux
- The flux of
heat between the ocean surface and atmosphere that results mainly from their
difference in temperature. The heat exchange is accompished via
molecular conduction in the first few millimeters above the surface
and via turbulent mixing and convection above that. The flux is
usually from the ocean to the atmosphere during the day and opposite
during the evening and night. See Peixoto and Oort (1992).
- separation formula
- A method for computing the adiabatic inter-hemispheric meridional
See Nof (1998).
- Acronym for the Seasonal Response to the Equatorial Atlantic
See Katz (1987) and
Richardson and Reverdin (1987).
- Seram Sea
- One of the seas that comprise the
Australasian Mediterranean Sea. This is centered at
about 130 E and 2-3 S and surrounded
by Buru and Seram to the south and by Halmahera and
the wester part of Irian Jaya to the north.
It connects with the
Arafura Sea to the southeast, the
Banda Sea to the southwest, and the
Halmahera Sea to the north.
It is variously spelled Ceram Sea.
- Seven Seas
- A term used long ago to collectively refer to
the Indian Ocean,
the Red Sea,
the Persian Gulf,
the Black Sea,
the Sea of Azov,
the Adriatic Sea and
the Caspian Sea.
The term is no longer much used although it is generally
conceded that a modern and more geographically generous
grouping would be the
the Southern Ocean,
the Indian Ocean,
the North and South Atlantic Ocean and
the North and South Pacific Ocean.
- shallow atmosphere approximation
- In meteorology, an approximation made to simplify the equations
of motion in spherical coordinates where the radial distance
r is replaced by a+z, where the altitude z is much smaller
than the radius of the Earth r.
See Salby (1992).
- shallow scattering layer
- A layer of marine organisms found over a continental shelf which
scatter sound. These layers are usually composed of patchy
and horizontally discontinuous groups whose horizontal dimensions
are usually less than their vertical dimensions.
There are also surface and deep scattering layers.
- shallow water approximation
- In oceanography, an approximation made for motions where the aspect
(where is the vertical length scale and
he horizontal scale) is small.
An example arises in the
study of the tides, where the horizontal scale of the wave
motion is thousands of kilometers and the vertical scale in
constrained by the maximum depth of the oceans, and as such
the applicable dynamics are those of shallow water gravity
waves, i.e. gravity waves that ``feel'' and are influenced
by the bottom.
The shallow water equations are obtained
(after Muller (1995)) by applying the
to the Boussinesq equations,
with respect to , and keeping only zeroth order terms.
where are the velocity components,
is the mean radius of the Earth,
are spherical polar coordinates where
is longitude, latitude, and radial distance,
is the Coriolis parameter,
is a constant reference density,
is the pressure,
is the deviation from the reference density and
is gravitational acceleration.
See Muller (1995).
- shallow water equations
shallow water approximation.
- Acronym for the Surface Heat Budget of the Arctic project, a
WCRP program to address the interaction of
the surface energy balance, atmospheric radiation, and clouds
over the Arctic Ocean.
- shelf sea
- A shallow sea that occupies a portion of a wide
continental shelf. This
is one type of
Compare to epeiric sea and
- Shelikof Strait
- A strait located between the Alaska Peninsula and
Kodiak Island at around 58N, 154W.
See Reed and Bograd (1995).
- Acronym for Studies of the Hydrology, Influence and Variability of the Asian
summer monsoon, a project sponsored by the European Commission.
The project goals are:
- to improve the simulation of the mean evolution of the monsoon, including
its intraseasonal characteristics;
- to assess the ability of models to simulate the intraseasonal characteristics,
particularly active/break phases, monsoon depressions, and sensitiivty of the
simulations to horizontal resolution;
- to investigate the mechanisms involved in the intraseasonal variability through
coordinated sensitivity experiments, i.e. to study the roles of land surface processes,
atmosphere-ocean interactions over the Indian Ocean and Arabian Sea, and internal
- to investigate the relationship between intraseasonal and interannual variability.
- short-crested waves
- A propagating surface gravity wave with a free surface elecation
which is doubly periodic in two perpendicular directions, along
and normal to the direction of propagation.
These can be produced either by the interaction of two
progressive waves angles to each other or by oblique
reflection from a maritime structure. The doubly periodic
nature is characterized by the pattern of island crests that
are formed at intersections of the component waves, rendering the
surface shape of such a wave system much more complex than
its wave components. The isolated crests thus produced propagate
in a combined direction with a wavelength and a definite crest
length equal to the distance between successive crests normal to
the former at the same time. The transverse distance between
adjacent crests is finite as opposed to the original two-dimensional
wave motions that combine to form short-crested waves, thus
giving them their name.
See Hsu (1990).
- Siberian Coastal Current
- See Weingartner et al. (1999).
- Siberian High
- One of the centers of action that tend to control large scale
weather patterns around the globe. This center
forms over Siberia during the winter and is centered
around Lake Baikal. The sea level pressure exceeds
1030 millibars from late November to early March.
The resulting anticyclonic circulation pattern is
enhanced by the tendency of the surrounding mountains
to prevent the cold air from easily flowing away.
This pattern is replaced by a low pressure pattern
in the summer related to the
- Acronym for Second International
- Sibuyan Sea
- A regional sea contained within the Philippines between the
northern island of Luzon and the central island group the
Visayan Islands. It is centered at about 122.5 E
and 12.3 N and connected to the
Visayan Sea to the southeast,
the Samar Sea to the east, the
Sulu Sea to the southwest via
the Tablas Strait, and the
South China Sea to the northwest
via the Verde Island Passage.
Geographical features of note include Sibuyan Island and
Marinduque Island as well as the Ragay Gulf in the southeast
arm of Luzon.
- Sierra Leone Basin
- An ocean basin located to the west of Africa at about
3 N in the east-central Atlantic Ocean.
See Fairbridge (1966).
- Acronym for Significant Interactions Governing Marine Aggregation,
a group that conducted an investigation of the aggregation of a diatom
bloom in a laboratory mesocosm to test the ability of coagulation
theory to predict aggregation in complex marine systems.
See Alldredge and Jackson (1995).
- sigma-t ()
- A conventional definition introduced into physical oceanography
for purposes of brevity. It is the remainder of subtracting
1000 kg m from the density of a sea water sample at atmospheric
where and are the in situ salinity and temperature.
The density of water ranges from 1000 kg/m3 to
about 1028 kg m for the densest ocean surface water, so sigma-t
ranges from about 0.00 to 28.00, with the units usually
- sigma-theta (
- A measure of the density of ocean water where the quantity
sigma-t is calculated using the
rather than the in situ temperature, i.e.
where is the in situ temperature.
- significant wave height
- A quantity defined by Walter Munk in 1944 (in an SIO technical report)
as the average height of the one-third highest
waves. He stated that this was about equal to the average height of
the waves as estimated by an experienced observer.
The quantity is usually written as or and
estimated using the calculated root-mean-square height of
the observed waves. The latter is calculated as
where is the total number of observed waves and their
heights. The significant wave height is estimated via:
See Bauer and Staabs (1998).
- significant wave method
- See S-M-B method.
- silicate pump
- A mechanism that acts in diatom-dominated communities to enhance the
loss of silicate from the euphotic zone to deep water compared to
nitrogen, which is more readily recycled in the grazing loop, thus
leading the system to silicate limitation.
The silicate pumping to deep water results in low silicate, high nitrate
conditions in the mixed layer.
In such situations silicate dynamics may control and dominate new
production processes and consequently control the rate at which newly
upwelled CO in the surface regions is reduced by the phytoplankton.
See Dugdale et al. (1995).
- siliceous ooze
- A fine-grained sediment of pelagic origin found on the
deep-ocean floor. It contains more than 30% siliceous material
of organic origin and is usually found below
the carbon compensation depth
at depths greater than 4500 m. Two types of this are
radiolarian oozes and
- Acronym for Sea Ice Model Intercomparison Project, an international
effort to develop an improved representation of sea ice in climate
SIMIP is carried out in the framework of ACSYS
within the WCRP.
A hierarchy of sea ice rheologies is evaluated on the basis of a
comprehensive set of observational data. Four different sea ice rheology
schemes are compared:
The same grid, land boundaries, and forcing fields are applied to
all models, with the prognostic equations solved on a spherical
grid for the whole Arctic with a resolution of 110 km and a daily
time step. The results as summarized at the project web site are:
- a viscous-plastic rheology;
- a cavitating-fluid model;
- a compressible Newtonian fluid model; and
- a simple free drift approach with velocity correction.
Overall, the viscous-plastic rheology yields the most
realistic simulation. In contrast,
the results of the very simple free drift model
with velocity correction clearly show
large errors in simulated ice drift as well as in
ice thicknesses and ice export through
Fram Strait compared to observation. The compressible
Newtonian fluid cannot
prevent excessive ice thickness buildup in the central
Arctic and overestimates the
internal forces in Fram Strait. Because of the lack
of shear strength, the
cavitating-fluid model shows marked differences
to the statistics of observed ice drift
and the observed spatial pattern of ice thickness.
Comparison of required computer
resources demonstrates that the additional cost for
the viscous-plastic sea ice
rheology is minor compared with the atmospheric
and oceanic model components in
global climate simulations.
See Kreyscher et al. (2000).
- Singular Spectrum Analysis
- A method of time series analysis, sometimes abbreviated as SSA, designed
to extract as much information as possible from short, noisy time
series without prior knowledge of the dynamics underlying the
series. It is a form of Principal Component Analysis
applied to lag-correlation structures of time series. It was
developed by Broomhead and King (1986)
and applied to the analysis of paleoclimate time series by
Vautard and Ghil (1989) and Vautard et al. (1992).
The SSA Toolkit
amongst several time series analysis tools.
SSA performs better than traditional Fourier analysis at separating
closely spaced relevant spectral peaks, but retains problems such
as the requirement of stationarity and the limitation to situations
of high SNRs. See Ruiz de Elvira and Bevia (1994).
- Abbreviation for Scripps Institution of Oceanography.
- Acronym for the Shuttle Imaging Radar-C used for geologic,
hydrologic, and oceanographic studies. It can image the Earth
through cloud cover and its sensitivity to surface roughness,
soil moisture, and sea-ice-water contrast makes it useful
in studies of geological features, canopy morphology, sea-ice
dynamics, and ocean surface temperature.
SIR-C Web site.
- Acronym for Systemes d'Informations Scientifiques pour la Mer or, in
translation, the French National Oceanographic Data Center.
SISMER Web site.
- In physical oceanography, a water mass.
See Tomczak and Godfrey (1994), p. 161.
- Six thermometer
- A self-registering maximum and minimum thermometer invented by
James Six (1731?-1793) of England in 1782. It consisted of
a U-shaped tube with mercury in the bend, one side filled with
alcohol, and the other partially filled. Indices marked the
highest and lowest temperatures. This was the most widely
used thermometer for taking deep sea temperatures up until
See Deacon (1971).
- Acronym for Seasonal Ice-Zone Experiment.
- A circulation controlled sedimentary basin that provides
part of the connection (along with
Kattegat) between the
North Sea and the
Baltic. It is surrounded by
Norway to the northwest, Sweden to the northeast, Denmark
and Kattegat to the southeast, and the North Sea to the
southwest. It is centered at approximately
9 E and 58 N and
is the deepest part ( 700 m) of the the Norwegian
The circulation in Skagerrak is counterclockwise with
North Sea water masses entering via the
Jutland Current in
the southwest, proceeding northeastward along the Denmark
coast, combining with some of the brackish
Baltic Current, turning
and flowing northwestward along Sweden, turning again and
Norwegian Coast Current (NCC)
as it flows southwestward along Norway, and finally leaving
Skaggerak and turning northwards as the NCC. There is also
a deep countercurrent beneath the NCC that injects high
salinity Atlantic water into the Skagerrak deep.
See Svansson (1975),
Rodhe (1996) and
Danielssen et al. (1997).
- Acronym for Skagerrak Experiment, an ICES
experiment carried out from spring 1990 to spring 1991 in the
Skagerrak. The main stage lasted four weeks with shorter and
less intensive stages occurring at other times.
The objectives of the experiment were to
identify and quantify the various water masses entering and
leaving the Skaggerak area and their variation over time,
to investigate the mechanisms that drive the circulation in
the area and its link with biological processes, and to
investigate the pathways of contaminants through the
Skagerrak. The project leader was B. Dybern.
- skin effect
- A temperature inversion in a thin near-surface ocean layer with
a thickness of several millimeters. This is a source of uncertainty
in radiometric measurements. The inversion layer, created mainly
by evaporation, results in an underestimation of the SST compared with
what it would be as determined by conventional methods in a layer
with a thickness ranging from several tens of centimeters to
See Kagan (1995).
- skin temperature
- The temperature of the millimeter thick skin layer at the surface
of the ocean.
The skin temperature is 0.1-0.5C cooler than
the water a few millimeters below the surface.
The skin is cooler than the layer just beneath because the net heat
balance at the surface is from the ocean to the atmosphere, even
during strong solar insolation and weak winds.
This is because the sensible and latent heat fluxes at the air-sea
interface are usually net losses from the ocean.
The net longwave emission at the surface is also usually a heat loss.
The incoming shortwave solar radiation
is absorbed by the upper layers, with the infrared absorbed in the
upper meter, the ultraviolet in the upper 3-5 m, and the visible in
the upper 100 m.
The shortwave absorption at the surface is therefore small, and
the ocean surface loses heat.
The heat lost is obtained from a flux from the interior via
molecular conduction since turbulence is damped close to the surface.
A large temperature gradient is required to accomodate the surface
heat losses, which causes the skin temperature to drop sufficiently
such that the resulting gradient can handle the flux from the
See Kantha and Clayson (2000).
- slab ocean
- A simple, non-dynamic ocean
model used in coupled model
simulations. SSTs are calculated from
surface energy balance
and heat storage in a fixed-depth mixed
layer but there are no ocean currents, i.e. we account for the
effects of local and temporal but not non-local processes.
The salient equilibration time of this type of model is that
of the slab ocean, usually on the order of about 20 years for
a 50 m thick slab.
- Acronym for System for Locating Eruptive Underwater Turbidity and
- slippery sea
- A phenomenon occurring in the wind-driven layer at the surface
of the sea. In conditions of strong surface heating, a well-mixed
warmer (and lighter) layer if formed, which is of limited depth
because the stabilizing density distribution inhibits vertical
mixing with the deeper, colder water. At the bottom of this
surface layer is a strong density gradient where the turbulence
is suppressed and the Reynolds stresses are small. A given
wind stress at the surface can thus accelerate the water to
produce stronger surface currents in this case compared to
an unstratified ocean. This is true because both the depth of
the layer involved is smaller and the retarding stress below
it is reduced. This creates the slippery sea phenomenon.
See Turner (1973).
- Slope Water (SW)
- A water mass that forms between the
Gulf Stream and the continental
shelf in the northwestern Atlantic Ocean. It is isolated by
the Stream from contact with oceanic water masses in its
depth range and therefore forms via interactions among
shelf water, water from the
Labrador Current, and water
from the Gulf Stream. The Slope Water thus formed extends
over the upper 1000 m of the water column
north of Cape Hatteras along the continental rise and has
a nearly linear T-S curve similar to that evinced by
North Atlantic Central Water (NACW). The T-S curve typically
extends from 21 C-36.0 to 15 C-35.1.
Slope Water is intermittently
transported by cyclonic rings across the Gulf Stream and into
the Sargasso Sea.
See Tomczak and Godfrey (1994).
- slow manifold
- A hypothetical N-dimensional manifold (i.e. surface) embedded in
the 3N-dimensional phase space of a primitive equation model that
is devoid of gravity waves. This has been called the Holy Grail
of initialization schemes for weather forecasting since if a
numerical weather prediction model could be initialized with
observations filtered to retain just their components on the
slow manifold, then the large-amplitude gravity waves that have
wrecked numerical forecasts since Richardson would no longer
be a problem. The concept was introduced by
Leith (1980) and is reviewed by Boyd (1995).
- Abbreviation for sea level pressure.
- S-M-B method
- A method of wave forecasting
developed by Sverdrup, Munk and Bretschneider, whence comes
the name. This approach yields predictions of
significant wave height
significant wave period
from known storm conditions, i.e. wind velocity , fetch
distance and storm duration .
This method can be used for a partially arisen sea.
Predictions are made
empirically using graphs of all the available data in terms
of the dimensionless ratios , ,
The empirical equations used to develop the graphs are:
where is the gravitational acceleration,
is the estimated wind velocity,
is the fetch length,
is the wind duration,
is the significant wave period and
is the significant wave height.
The constant values are
= 6.5882, = 0.0161, = 0.3692, = 2.2024 and
See Komar (1976).
- See Pingree and LeCann (1993).
- Abbreviation for Sveriges Meteorologiska och Hydrologiska Institut or
Swedish Meterological and Hydrological Institute.
SMHI Web site.
- Acronym for Shelf Mixed Layer Experiment, a WHOI research program
designed to study the response of the oceanic surface boundary layer
over the continental shelf to atmospheric forcing.
SMILE took place over the northern California shelf between Pt. Arena
and Pt. Reyes from mid-November to mid-May 1989.
See Alessi et al. (1991).
- Abbreviation for Scanning Multichannel Microwave Radiometer,
an instrument that has been on board both
It produced earth location and time-tagged SSTs, surface
wind stress, atmospheric water vapor, liquid water content,
and precipitation rate information.
See Liu (1984).
- Acronym for Summer Monsoon Experiment, a program taking place from
May 1 to August 31, 1979 in eastern African, the northern part of
the Indian Ocean, the Arabian Sea, the Bay of Bengal, and in
adjacent continental areas.
- Abbreviation for Synthesis and Modeling Working Group, a