- Snellius Expedition
- An oceanographic expedition taking place in 1929-1930 in the
southwest Pacific Ocean.
- Snellius II Expedition
- See van Aken (1988).
- See Southern Oscillation.
- Acronym for Satellite Ocean Analysis for Recruitment, a
- Acronym for the School of Ocean and Earth Science and Technology
at the University of Hawaii at Manoa.
It was established in 1988 and currently has approximately 700
faculty and staff.
It consists of departments in Geology and Geophysics, Meteorology,
Oceanography, and Ocean Engineering, as well as three institutes:
- Hawaii Institute of Geophysics and Planetology (HIGP)
- Hawaii Institute of Marine Biology (HIMB)
- Hawaii Natural Energy Institute (HNEI)
- 1. Acronym for Sound Fixing and Ranging channel, another name for
the sound channel.
2. Acronym for SOund Fixing And Ranging floats, subsurface floats
used since the mid 1970s
that freely drift at prescribed pressures. These provide direct
measurements of the ocean circulation by sending acoustic
pulses, typically at 300 MHz, once a day which can be used
to calculate their positions from their Times of Arrivals (TOAs)
at listening stations moored near the
SOFAR channel depth at
known geographical positions.
See Rossby and Webb (1970).
- Acronym for Southern Ocean Iron (Fe) Experiment. The original name for
this was IronEx III.
- Acronym for Surface of the Ocean, Fluxes and Interactions experiment.
See Dupuis et al. (1993).
- soft tissue pump
- See organic matter pump.
- See Southern Oscillation Index.
- Acronym for Southern Ocean Iron RElease Experiment, an experiment taking
place from January 31 to March 1 1999 on the R.V. Tangaroa in
the Southern Ocean.
A patch of seawater was enriched with iron to test the hypothesis that iron
limits the primary production of phytoplankton.
The iron and sulphur hexafluoride (as a tracer) were initially released
on Feb. 10 at a site with a mixed layer depth of about 65 m and with
low chlorophyll levels. The dissolved iron concentration was
considerably elevated over the 50 square kilometer area, although the
levels quickly decreased leading to three more iron infusions during the
13-day experiment. The patch moved about 40 nautical miles eastward
and expanded to about 150 square kilometers during the experiment.
Five days after the initial release significant increases in algal
photosynthetic competence were observed, followed by elevated algal
biomass. Chlorophyll and upper ocean dimethylsulfide
levels increased significantly by the
end of the experiment, while macronutrient levels, the partial pressure
of carbon dioxide, and the contnet of total dissolved inorganic carbon
See Boyd et al. (2000) and
Boyd and Law (2001).
- solitary wave
- See soliton.
- A fundamentally nonlinear wave that propagates undistorted over
The soliton or solitary wave was
discovered by Scottish engineer John Scott Russell
(1808-1882) in 1834 while conducting experiments to determine the most
efficient design for canal boats.
He describes his first observations of what he called a
``Wave of Translation'' ():
I was observing the motion of a boat which was rapidly
drawn along a narrow channel by a pair of horses, when the
boat suddenly stopped - not so the mass of water in the
channel which it had put in motion; it accumulated round the
prow of the vessel in a state of violent agitation, then
suddenly leaving it behind, rolled forward with great velocity,
assuming the form of a large solitary elevation, a rounded,
smooth and well-defined heap of water, which continued its
course along the channel apparently without change of form
or diminution of speed. I followed it on horseback, and
overtook it still rolling on at a rate of some eight or
nine miles an hour, preserving its original figure some thirty feet long
and a foot to a foot and a half in height. Its height
gradually diminished, and after a chase of one or two miles I lost it in
the windings of the channel. Such, in the month of August
1834, was my first chance interview with that singular and
beautiful phenomenon which I have called the Wave of Translation.
See Bullough (1988) and
Sander and Hutter (1991) for the historical development of the
concept of solitary waves,
which weren't wholly appreciated until the advent of digital
computers made it possible to much more thoroughly investigate
their characteristics and use them to model physical situations.
Today solitons or solitary waves are used as a constructive element
to formulate the complex dynamical behavior of wave systems in almost
all facets of science, e.g. hydrodynamics, nonlinear optics, plasmas,
shock waves, tornados, the Great Red Spot of Jupiter, etc.
- Acronym for Sounding Oceanographic Langrangian Observer, a second-generation
ALACE float designed to correct the design flaws
of the latter.
The SOLO uses a single-stroke hydraulic pump allowing full up-down
control, and eliminates the internal oil bladder.
See Davis et al. (2001).
- Solomon Sea
- More later.
- solubility pump
- The process by which the ocean maintains a vertical gradient in
DIC (CO2 plus bicarbonate and carbonate ions) - such
that DIC is concentrated in the deep ocean - as
a result of gas exchange.
Surface water at equilibrium with a given CO2 concentration
will increase its DIC concentration (uptake CO2) when the
water temperature decreases since the solubility and
dissociation of CO2 increase in cold water. The regions
of deep water formation are located in high latitudes so
the deep ocean is filled with cold water with relatively
high DIC concentration. It is estimate that about 50% of
the vertical DIC gradient can be accounted for by this
See Najjar (1991) and
- solution drift
- See climate drift.
- Somali Current
- A current near the western boundary of the Indian Ocean that
flows southward during the boreal winter and northward during
The southward flow during the northeast monsoon is limited
to south of 10N. It occurs first in early December
near the equator and expands rapidly north in January with
velocities from 0.7-1.0 m/s. The surface flow reverses in
April during the inter-monsoon period, and develops into an intense
jet during the southwest monsoon with velocities reaching 3.5 m/s in June.
During the southwest monsoon a two gyre system develops in the region - the
Great Whirl between 5-10N with clockwise rotation and a secondary
eddy towards its south.
This two gyre system is stable until August or September, when the southern
gyre propagates northward and merges with the Great Whirl.
This has also been called the
East Africa Coast Current.
See Schott (1983) and
Schott and Fischer (2000).
- Somali Jet
- See Halpern and Woiceshyn (1999).
- Acronym for Sampling, Observations and Modeling of Atlantic Regional
Ecosystems, a program whose overall goal is to unify the diverse
European research groups investigating the functioning, effects and
responses of the regional ecosystems of the Atlantic Ocean and shelf
seas to anthropogenically forced and climate related changes.
The scientific goals of SOMARE include improving knowledge of:
- biogeochemical and bio-optical provinces of the ocean basins and
marginal seas of the Atlantic Ocean in
terms of bio-optical, physical and biogeochemical properties;
- bio-optical properties and biological processes including
plankton community structure and nutrient
cycling using on-line, autonomous and towed sensor methods;
- spatially extensive calibration, validation and quality assurance
of remotely sensed observations of oceanic biology;
- novel climatologies of key biological state variables and process
- development of sub-models of key biological processes for incorporation
in basin-scale productivity models.
- Abbreviation for Ship of Opportunity Program, an IOC project
that uses merchant and other volunteer ships that transit a
series of tracklines over existing trade routes. These ships
deploy XBTs and other sampling instrumentation to obtain upper
ocean thermal and salinity data.
The primary goal of SOOP is the fulfill upper ocean data requirements
established by GOOS and
GCOS, which can be met at present by
measurements from ships of opportunity.
- Soret effect
- In fluid mechanics, mass diffusion caused by a temperature gradient.
See Hurle and Jakeman (1971).
- Acronym for Sound Surveillance System, a component of the U.S. Navy's
Integrated Undersea Surveillance Systems (IUSS) network used for deep
ocean surveillance during the cold war.
SOSUS consists of bottom-mounted hydrophone arrays connected by
undersea communication cables to onshore facilities.
The arrays are primarily installed on continental slopes and seamounts
at locations optimized for undistorted long range acoustic
Beginning around 1990, the Navy allowed SOSUS to be used for various
See Nishimura and Conlon (1994).
- sound channel
- A narrow channel in which sound waves can be effectively trapped.
A region of minimum sound speed is created where the bottom of the
thermocline meets the top of the deep isothermic layer. The velocity
of sound slows as water temperatures decrease approaching the
thermocline from above. The temperature is relatively constant
below the thermocline, but increasing pressure causes the speed of
sound to increase downwards. This causes obliquely traveling horizontal
sound waves to vertically bend back and forth within the sound channel
and travel great distances with relatively minor energy loss.
This is also known as the SOFAR channel.
- source water type
- In physical oceanography, a point on a T-S diagram
indicative of a water mass. In practice, few
if any water masses have T-S values identical to that of their source
water types due to transformation by atmosphere-ocean interface processes and/
mixing, but they are almost inevitably within the theoretical standard
deviation and as such readily identifiable as to their origin.
See Tomczak and Godfrey (1994).
- South Atlantic Bight
- See Boicourt et al. (1998).
- South Atlantic Central Water (SACW)
- A variety of Central Water
found in the Atlantic Ocean south of about 15N.
It shows uniform properties throughout its range, with the T-S
curve well described by a straight line between the points
5C, 34.3 and 20C, 36.0. Part of the SACW
is thought to be
Indian Central Water (ICW) brought into
the Atlantic by
Agulhas Current intrusions.
See Stramma and England (1999).
- South Atlantic Current
- The current band of increased zonal speeds associated with
the Subtropical Front (STF)
in the South Atlantic Ocean.
It originates in the western Atlantic as the STF becomes
clearly distinguished from the Brazil Current front somewhere
between 40 and 45 W.
It then flows eastward typically to the north of the STF and closes the
circulation in the South Atlantic subtropical gyre by becoming
its southern limb. The SAC is clearly separated from the ACC
by a region of weak flow just to the south of the STF, and is
seen to not follow the STF exactly in some observations.
It is recognizable as an enhanced current core at depths of
800-1000 m and has an average volume transport of about 30 Sv
in the upper 1000 m in the western Atlantic (reaching as high
as 37 Sv). The transport diminishes to less than 15 Sv in
the vicinity of southern Africa where it turns northward to feed
the Benguela Current.
See Stramma and Peterson (1990) and Peterson and Stramma (1991).
- South China Sea
- A regional sea in the western Pacific Ocean centered at about
115 E and 12 N that includes the
Gulf of Thailand and the
Gulf of Tonkin.
It is bordered to the west by Vietnam, Thailand and the
Malay Peninsula, to the south by a line joining the southern
tip of the Malay Peninsula to Borneo, to the east by Borneo,
the Phillipines and Taiwan, and to the north by the Taiwan
Strait and China. It covers an area of 3,685,000 km,
has a volume of 3,907,000 km, a mean depth of 1060 m,
and a maximum depth of 5016 m.
It is connected to the
East China Sea via the
Taiwan Strait, the
Andaman Sea via the Strait
of Malacca, the
Java Sea via the Karimata Strait, and
to the Philippine Sea via
Luzon Strait, and the
Sulu Sea via the Balabar Strait and
the Mindoro Channel. The main freshwater input from rivers
is from the Red and Mekong Rivers of Vietnam and the Si Kiang
River of southern China.
See Qu et al. (2000).
- Southeast Indian Subantarctic Mode Water (SEISAMW)
- A type of
Subantarctic Mode Water formed
in the southeastern Indian Ocean south of Australia.
It is the dominant mode of ventilation for the Indian Ocean, leading
to a subsurface oxygen maximum layer extending northward into the
tropical and northern Indian Ocean.
- Southeast Pacific Deep Water (SPDW)
- The SPDW flows through the
Drake Passage with the
ACC south of the
Polar Front, at which point
it is identifiable by its potential temperature
salinity (34.703 S 34.710), and its silicate
maximum (reaching 140 mol kg).
It is the densest water mass of the ACC system in
the Drake Passage.
When crossing the Scotia Sea, it
is drastically cooled (by 0.14C) and freshened
(by 0.018) along isopycnals via mixing with
WSDW and WDW in the
This results in the SPDW south of the Southern ACC Front being transformed
into WDW and becoming incorporated into the
ACC, while north of the front two cores carrying
modified SPDW exit the Sea. One of these is on the northern flank of
the Southern ACC Front south of South Georgia, having followed the front
from Drake Passage. The other overflows the North Scotia Ridge through
Shag Rocks Passage and can be found just south of the
Polar Front skirting the Falkland Plateau.
See Siecers and Nowlin Jr. (1984).
- South Equatorial Countercurrent
- An eastward current in the Atlantic and Pacific that flows
between 5 and 10 S., the limited evidence for which shows
it to be much less well developed than the
North Equatorial Countercurrent (NECC).
In the Indian Ocean the SECC is almost
totally confined between the equator and the northern boundary
South Equatorial Current (SEC)
at 4 S.
This was first described by Reid (1959) and the evidence is
later reviewed by
Leetmaa et al. (1981).
- South Equatorial Current
- A westward flow in the Atlantic and Pacific located south of the
North Equatorial Countercurrent (NECC) generally
below 5 N. It flows between about 3 N and
10 in the Pacific with speeds estimated at around
50 to 65 cm s and an average mean transport of
17 SV, although this latter quantity annually varies by about
10 Sv about the mean.
The SEC is strongest during
July and August and usually vanishes during the northern winter
and spring. This is also seen in the Indian Ocean south of
See Leetmaa et al. (1981) and
- South Equatorial Current Bifurcation
- The phenomenon wherein the Atlantic
South Equatorial Current (SEC) - upon approaching
the easternmost tip of South America - splits into the
Brazil Current flowing to the south and
the North Brazil Current flowing
northwestward along the northern coastline of Brazil.
- South Equatorial Undercurrent
- An eastward flow in the Atlantic Ocean whose core is located near
200 m depth a few degrees south of the Equator. A satisfactory
dynamical explanation for this is as yet nonexistent.
See Tomczak and Godfrey (1994), p. 260.
- South Java Current
- See Tomczak and Godfrey (1994).
- South Subtropical Front (SSTF)
- The southern boundary of the
Subtropical Frontal Zone (STFZ).
- South Tropical Countercurrent
- See Donguy and Henin (1975).
- Southern ACC Front
- A front in the
Southern Ocean that
Antarctic Zone (AZ) to the north
Continental Zone (CZ) to the south.
The position of the SACCF is usually indicated by a distinct
temperature gradient along the -maximum of the
Upper Circumpolar Deep Water
(UCDW) as it shoals southward to near 500 m.
The property indicators of the SACCF are
1.8 along -maximum at Z 500 m,
0 along -minimum at Z 150 m,
S 34.73 along S-maximum at Z 800 m, and O 4.2 ml/l
along O minimum at Z 500 m.
The SACCF is one of three fronts found in the
Current (ACC), the others being (to the
Polar Front (PF) and the
Subantarctic Front (SAF).
See Orsi et al. (1995).
- Southern Ocean
- In oceanography, an unofficial term used to describe the oceans
surrounding the continent of Antarctica, which comprise approximately
22% of the world's ocean area. The northern limit
is the broad zone of transition where the permanent thermocline
reaches the surface at the
Subtropical Convergence (STC).
The southern limit is the continent of Antarctica.
It is distinguished from the other oceans by the relative uniformity
of its hydrography and circulation, and that it
influences more than it is influenced by the others.
The Southern Ocean bathymetry consists of three major basins where the depth
exceeds 4000 m separated by three major ridges that reach at least
to the 3000 m level. These are (proceeding
from the Pacific sector west): (1) the Amundsen, Bellingshausen, and
Mornington Abyssal Plains, sometimes called the Pacific-Antarctic
Basin, (2) the Macquarie, Pacific-Antarctic, and Southeast Indian
Ridge sytem, (3) the Australian-Antarctic Basin, (4) the Kerguelan
Plateau, (5) the Ender and Weddell Abyssal Plains, also known as
the Atlantic-Indian Basin, and (6) the Scotia Ridge.
See Belkin and Gordon (1996).
- Southern Oscillation
- The name given to the atmospheric component of the
El Nino/Southern Oscillation
(or ENSO) phenomenon. The SO is a large-scale shift in atmospheric
mass between the western and eastern Pacific, monitored by computing
the SOI. An SOI indicating El Nino conditions means
that there is reduced rainfall over the Indonesian region and that
the west Pacific convective center is displaced eastward along the
- Southern Oscillation Index
- An index that is calculated to monitor the ENSO phenomenon. It is
defined as the pressure anomaly at Tahiti minus the pressure
anomaly at Darwin, Australia. Anomalously high pressure at Darwin
and low pressure at Tahiti are indicative of El Nino conditions.
- Southern South Equatorial Current (SSEC)
- One of three distinct branches into which the
South Equatorial Current
splits in the western South Atlantic.
See Stramma (1991).
- Southern Subsurface Countercurrent (SSCC)
- An eastward flowing countercurrent that flows beneath the surface
east of 155 in the South Pacific Ocean.
It flows between the eastward flowing
South Equatorial Countercurrent (SECC) to the north and the
South Equatorial Current to the south.
See Gouriou and Toole (1993).
- South Pacific Equatorial Water (SPEW)
- In physical oceanography, a water mass partly
formed by convective sinking of surface water at SSTs of 26 C
and above in the tropics in the area
of Polynesia. It is identified at temperatures greater than 20 C
by a higher salinity than WSPCW, although
below 20 C it seems to be a mixture of
WSPCW and ESPCW.
See Tomczak and Godfrey (1994), p. 166.
- South Pacific Tropic Water (SPTW)
- A water mass identified as a salinity
(35.25 psu) maximum with homogeneous oxygen concentration
(about 3.3 ml l) around 25
it is found in the equatorial region south of 5N.
See Qu et al. (1999).
- South Trench Current
- See North Sea.
- Southwest Area Monsoon Project (SWAMP)
- A NSSL project begun
in 1990 to measure the central Arizona
thunderstorm environments, examine the local monsoon
structures and moisture fluxes, and study Mexican
convective systems. The field operations for SWAMP
began in 1990 and included scientists and technicians
from several institutes and laboratories.
SWAMP Web site.
- Southwest Monsoon Current
- See Vinayachandran et al. (1999).
- Acronym for Southern Ocean Waves Experiment, an international
collaborative air-sea interaction experiment in which a specially
instrumented meteorological research aircraft simultaneously
gathered atmospheric turbulence data in the marine boundary layer and
sea surface topography data over the Southern Ocean for a wide
range of wind speeds. The aim was to increase present knowledge of
severe sea state air-sea interaction.
SOWEX was carried out from June 10-16, 1992 over the Southern Ocean
off the southwest coast of Tasmania, Australia at 42-45S,
See Banner et al. (1999) and
Chen et al. (2001).
- Soya Current
- An extension of the
Tsushima Current that
flows northward from the Japan Sea
into the Okhotsk Sea via the
Soya Strait. It is a fairly rapid curent with velocities
reaching 1 m/s and traveles close to the coast with the character
of a boundary current.
- Soya Strait
- See Okhotsk Sea.
- Abbreviation for Salinity-Profiling ALACE
- Spanish Basin
- See Iberia Basin.
- Abbreviation for South Pacific Convergence Zone, an atmospheric
convergence zone in the southwestern Pacific Ocean that is
characterized more by a convergence in wind direction than as
a wind speed minimum. It extends from east of Papua New
Guinea in a southeastward direction towards 120 E and
See Philander and Rasmusson (1985).
- specific heat
- A thermodynamic quantity indicating the rate of change of heat
content with temperature. More specifically, this is
the heat required to raise the temperature of a unit mass of a given
substance by one degree. It is normally expressed in units of
calories/gm K. The specific heat of water is 1.00
cal/gm K (although this varies about 1% with temperature),
and the specific heat of dry air at constant pressure (C)
is 0.240 cal/gm K and at constant volume (C)
0.171 cal/gm K. For water vapor the constant pressure
(C) value is 0.441 and the constant volume (C)
value 0.331 cal/gm K.
For seawater, the specific heat at surface pressure is calculated in
two stages. First, the value in joules per kilogram per degree Kelvin
for fresh water is calculated as:
Then, the value at a given salinity is calculated with:
The standard deviation of the algorithm fit is 0.074,
and a check on the formula is given by
See Millero et al. (1973) for the derivation and details.
Values at nonzero pressures are found using the following relation:
where is the specific volume.
See also Cox and Smith (1959).
- specific humidity
- The ratio of the mass () of water vapor to the mass
( + ) of moist air in which is contained, where
is the mass of dry air, or
- specific volume
- The reciprocal of density. In the determination of the specific
volume of sea water, the specific volume
where the second through seventh terms on the right-hand-side are
specific volume anomaly
and the second through fourth terms the
- specific volume anomaly
- The portion of the
specific volume differing from a
standard specific volume determined at a salinity of 35 ppt,
a temperature of 0 C, and the pressure at the depth at which
the sample was taken.
This has also been known as the steric anomaly and the
anomaly of specific volume.
- spectral element method
- A method for approximating solutions to the governing equations
of fluid motion in the ocean. It was developed to combine the
geometrical flexibility of the traditional low-order finite element
methods with the accuracy and high convergence rates of spectral
methods. See Iskandarani et al. (1995).
- spectral nesting
- See nested modeling.
- spectral signature
- This refers to the particular form or shape evinced by the
power spectrum calculated from
the data comprising the time series of a process.
For example, if the spectrum shows peaks at around 20, 40 and
100 thousand years it might be said to have the spectral
signature of Milankovitch orbital variations.
- See South Pacific Equatorial Water.
- spherical approximation
- The fundamental geometric approximation in oceanography. It maps
the approximate oblate spheroidal shape of the
geoid on a sphere and introduces spherical
longitude, is latitude, and radial distance.
This approximation also assumes that the metric coefficients
do not vary with radial distance, and that
This approximation represents the lowest order in an expansion of
the metric with respect to two small parameters
where is the half distance between the foci of
the geoid, the mean radius of the Earth, and the ocean
depth. A vertical coordinate
is also introduced.
See Stommel and Moore (1989) and Muller (1995).
- Spice Experiment
- An exploratory experiment to observe spiciness
in the upper ocean, including the
mixed layer, at horizontal scales of
10 m to 1000 km.
The objectives of the Spice Experiment are:
- to quantify the
density ratio in the mixed layer and
- to find if salinity varies on shorter horizontal scales than
- to confirm that there is more spiciness in the mixed layer than in
the seasonal thermocline; and
- to find where and over what length scales the reduction in
The data for the experiment were taken from a cruise in the eastern
North Pacific between 25 and 35 N from Jan. 24 to Feb. 20, 1997.
Measurements were made using a
SeaSoar equipped with a
CTD and a fluorometer.
- The variability of temperature and salinity along a surface of
constant density due to air-sea fluxes, turbulent mixing and
- Spilhaus, Athelstan (1912-1998)
- Inventor of the bathythermograph and
possibly the only oceanographer to have ever authored a regular
According to his obituary in The Economist,
Spilhaus can also apparently be blamed for the Roswell Incident that's
spawned an entertainment industry:
In 1947 the Americans were working on ways to monitor nuclear tests in the Soviet Union. One plan was to put aloft
balloons equipped with the necessary detection equipment. The first experiments were failures. The balloons all blew
away. Mr Spilhaus, then a professor of meteorology at New York University, was brought in. As a weather man, so
the reasoning went, surely he would know how to ensure that the balloons stayed quite steady in the stratosphere.
On June 4th 1947 the Spilhaus prototype was launched. On July 7th it came down with a bump, disintegrating on a
ranch near Roswell in New Mexico. The rancher phoned the local sheriff. He thought the debris might have come from
"a flying disc". By the time the story got into the newspapers the "disc" had become a flying saucer. A neighbour of
the rancher later said that in the debris there was "something like aluminium, something like satin, something like
well-tanned leather in its toughness, yet was not precisely like any one of those materials". Could this have been a
dead alien, or possibly several? Many people came to think so.
An air force team removed every scrap of debris, assuring reporters that it was just an ordinary balloon, nothing to be
bothered about; and compounding suspicions that the federal government was trying to cover up the fact that aliens
had landed, fearing panic by the public. It was not until 1994 that it disclosed the background to the incident. Even
now, the government version is widely disbelieved. The myth was much more interesting. Mr Spilhaus could say little:
this was a secret of the cold war. But the fact that he was known to be associated with the incident only added to
public speculation about it. Mr Spilhaus enjoyed playing the role of a slightly dotty scientist, a bit of a dreamer, or, as
he called himself in later life, a "retired genius".
- spin up
- In numerical modeling, this refers to the transient initial
stages of a numerical ocean simulation when the various fields
are not yet in equilibrium with the boundary and forcing functions.
Three techniques are generally used to initialize and spin up
the ocean components
of coupled models: (1) initializing with climatological values of
temperature and salinity (typically using the
throughout the volume of the ocean; (2) start with the aforementioned
Levitus ocean and then spin it up for about 100 years using
surface climatological forcing; (3) run the ocean to equilibrium by
either combining surface forcing terms with atmospheric model fluxes or
just using the surface forcing (and perhaps using an
acceleration method with either option).
The entire ocean is not in equilibrium using the first two methods,
although the second method does allow the thermocline to adjust to
equilibrium. This is due to both
systematic errors and other
shortcomings in the Levitus data. The third method may produce
and ocean in equilibrium, but it may differ considerably from the
observed ocean and the circulation may be distorted. For example,
the deep ocean is often too warm using this method.
- Abbreviation for subpolar mode water.
- spring retardation
- See age of tide.
- spring tide
- The high tides of greatest amplitude caused
by the Earth, Sun and Moon being almost co-linear. This causes
the gravitational pulls of both the Sun and Moon to reinforce
each other. The high tide is higher and low tide is lower than
the average, and spring tides occur twice a month at the times
of both new moon and
full moon. See also
- Abbreviation for
South Pacific Tropical Water.
- Acronym for Self-Propelled Underwater Research Vehicle.
See Widditsch (1973).
- Acronym for SeaWiFS Quality Monitor.
See Hooker and Aiken (1998).
- A violent wind that begins suddenly, lasts for a short time,
and dies suddenly. It is sometimes associated with a
temporary change of direction.
- squall line
- One of the most severe kinds of storms in the tropics.
The system is typically hundreds of miles long and consists of
a line of active thunderstorms. The cumulonimbus clouds
representing individual storms have lifetimes on the order of an
hour or less, but new ones replace dying cells allowing the
system as a whole to last from hours to days. They form
preferably over land and move with speeds from 10-20 m/s.
In a squall line warm moist air enters the base of the cloud
at its leading edge and rises in a convective updraft with
accompanying condensation. An extensive cloud anvil forms to
the rear of the convective tower with precipitation falling
from both the main cloud column and the anvil. The evaporation
of this precipitation into dry mid-tropospheric air leads to
cooling and downdrafts concentrated in the region of intensive
convection although extending to the rear of the squall line.
This downward rushing cold air causes a pseudo cold front or
gust front at the leading edge. This front undercuts the warm
moist air ahead, causing more convection and new cumuliform
clouds ahead of the line and fostering the propagation of the
See Hastenrath (1985).
- See Singular Spectrum Analysis.
- Acronym for the single-frequency solid-state radar altimeter flow
flown as an experimental instrument on the
TOPEX/POSEIDON mission (with this
being known as the POSEIDON instrument).
The SSALT, a solid-state Ku-band (13.65 GHz) altimeter, was developed
by the French (CNES) as a demonstration project for a low-power,
low-weight altimeter for future Earth-observing missions.
It shares the same antenna with ALT, the
operational altimeter, and thus cannot be operated at the same time.
The SSALT was operated 12.5% of the time during the 6 month verification
phase of the mission, and thereafter for one (10 day) cycle approximately
every 10 cycles.
- 1. Abbreviation for
Southern Subsurface Countercurrent.
2. Abbreviation for
- Abbreviation for
- Abbreviation for sea surface temperature.
- Abbreviation for
South Subtropical Front Zone.
- Abbreviation for
Sargasso Sea Water.
- Abbreviation for
Seismic Sea-Wave Warning System.
- 1. See numerical stability.
2. In physical oceanography, a measure of the tendency of a
water parcel or particle to move vertically in comparison with
its surroundings. Neglecting adiabatic
effects, the stability is defined (over short vertical distances) by
where is the density and the vertical coordinate.
There is a correspondingly more complicated expression for the
stability when adiabatic effects are taken into account as is
usually necessary at great depths.
Typical values of in the upper 1000 m range from
100 to 1000 x /m, with the largest values generally
occurring in the upper few hundred meters. Below 1000 m
values decrease to less than 100 x /m and can
get as small as a hundredth of that in deep trenches.
- stability frequency
- See buoyancy frequency.
- Acronym for Stable Antarctic Boundary Layer Experiment.
- Acronym for Subtropical Atlantic Climate Study, a NOAA project
directed at increased understanding of the role of western boundary
currents of the Atlantic ocean in meridional heat flux and
development of strategies to monitor important western
See Molinari (1989).
- staggered grid
- In numerical analysis this refers to a
computational grid in or on which
separate dependent variables are represented on alternate or staggered
grid points. For example, a 1-D equation set for pressure and velocity
would be solved on a grid where the pressure is represented at points
n, n+2, n+4, etc. while the velocity is represented at
n+1, n+3, n+5, etc. This procedure can confer numerical advantages
and is also used for problems with more than one spatial dimension.
See Kowalik and Murty (1993).
- stagnant film model
- The simplest of several models developed to understand the
processes that determine the gas flux in and near the liquid
boundary layer that is the air-sea interface. It assumes that
the boundary layer is a discrete, stagnant layer in which only
molecular diffusion takes place. This stagnant layer sits on
top of a well-mixed, purely turbulent layer. The flux across
the interface is assumed to be equal to the flux in the stagnant
film which, using
Fick's law, gives a linear
concentration profile within the film. This leads, with the
additional use of
to an expression for the flux
involving the gas concentration at the base of the film (),
the partial pressure of the gas in the atmosphere (), the solubility
of the gas in seawater (), and the
piston velocity (), i.e.
See Najjar (1991).
- Standard Atmosphere
- An idealized, dry, steady-state approximation of the atmospheric
state as a function of height that has been adopted as an engineering
reference. It was not computed as a true average but rather
approximates average atmospheric conditions at mid-latitudes.
It is a piecewise continuous curve consisting of straight-line
segments with breaks at 11, 20, 32, 47, 51 and 71 km. The
surface temperature is
C and the gradients, starting
from the surface, are -6.5, 0.0, 1.0, 2.8, 0.0,-2.8, and -2.0
Pressure variations can be found from this by combining
the hydrostatic equation
with the equation of state for dry air and integrating the
with respect to height.
See Minzner (1977).
- standard density
- A conventional value for the density of mercury, adopted for the
sake of uniformity in the conversion of pressure readings from
units of pressure to units of height (or the converse). The
value adopted by the WMO is the density at
0 C, i.e. 13.5951 gm/cm.
- standard gravity
- A conventional value for the acceleration due to gravity, adopted
for the sake of uniformity. The value adopted by the
WMO is 980.665 cm/sec.
- standard seawater
- See Culkin and Smed (1979),
Culkin and Ridout (1998) and
Bacon et al. (2000).
- Acronym for Southern Tropical Atlantic Regional Experiment,
a project within BIBEX.
STARE is an aircraft- and ground-based measurement program
initiated in May 1990 by a committee of scientists from
Europe, Brazil and the U.S. to investigate the sources
of trace gases, their atmospheric transport, and the chemical
processes in the atmosphere which lead to elevated levels of
O, CO, and other trace gases over the southern
tropical Atlantic Ocean. The field campaigns conducted
under STARE were TRACE-A,
SAFARI, and SA'ARI.
See Andreae et al. (1996).
- The property requiring that certain statistical properties of
a stochastic process be invariant
with respect to time. As some have noted, the strict satisfaction
of this requirement is impossible if one lends creedence to the
Big Bang theory of universal origin, although inroads can be
made towards satisfaction on less strict and more pragmatic
- stationary planetary wave
- Departures of the time average of the atmospheric circulation
from zonal symmetry. They result from east-west variations in
surface elevation and temperature associated with the continents
and oceans. See Hartmann (1994).
- statistical downscaling
- A procedure wherein local or regional climate characteristics
are inferred from the output of GCMs that
don't explicitly resolve such scales. Statistical relationships
between observed local climate variables, e.g. surface air temperature,
precipitation, etc., and observed large-scale predictors are
developed and then applied to the same large-scale predictors in
the GCM output to predict the local climate variables. This
method has been shown to produce local temperature and precipitation
change fields that were significantly different and had a finer
spatial scale structure than those generated by directly interpolating
large-scale GCM fields.
See Houghton and Filho (1995).
- statistically robust
- Statistical results which are relatively insensitive to the presence of a
moderate amount of bad data or to inadequacies in the statistical model
being used, and that react gradually rather than abruptly to
perturbations of either. See Chave et al. (1987)
for a discussion of this in relation to geophysical data.
- 1. See Subtropical Convergence.
2. See South Trench Current.
- Abbreviation for Salinity-Temperature-Depth.
- A temperature profiler for measuring the oceanic thermal boundary
layer at the ocean-air interface.
See Mammen and von Bosse (1990).
- steric anomaly
- Another name for the
specific volume anomaly.
- steric height
- In oceanography, a quantity introduced to determine the distance
or depth difference between two surfaces of constant pressure.
The steric height is defined by
where and are the depths of the pressure surfaces,
specific volume anomaly,
the temperature, the salinity, the pressure, and
a reference density.
It has the dimension of height and is expressed in meters.
- STERNA Expedition
- A two-ship study carried out in the
Bellingshausen Sea, Southern
Ocean from October to December, 1992.
The STERNA project, carried out aboard the Royal Research Ships
James Clark Ross and Discovery, was the final field-work
phase of the NERC-funded BOFS (the major
U.K. contribution to the IGBP JGOFS over the
The study was originally developed to also include
an investigation of biogeochemical
fluxes during the spring ice-melt in the
Greenland Sea, and was named STERNA
after the migrations carried out by the tern Sterna paradisea, during
which individual commonly spend alternate summers in each polar region.
The northern component was cancelled because of major refitting work
on the research ships, but the name was retained.
The objectives of the STERNA Expedition were:
See Turner and Owens (1995).
- to determine ocean-atmosphere exchanges of radiatively active
gases, and the factors influencing such fluxes, over a wide
- to investigate the interactions among the biological, chemical
and physical processes that control carbon fluxes in the
- to assess the impact of sea-ice on biogeochemical fluxes; and
- to determine the export of biogenic material from the upper
- Abbreviation for
- Abbreviation for
Subtropical Frontal Zone.
- still water level
- The level of the sea with high frequency motions such
as wind waves averaged out.
See also mean sea level.
- Abbreviation for
Subtropical Mode Water.
- stochastic process
- A reasonably strict definition of this (also called a random process)
is a family of random variables indexed
by t, where t belongs to some index set T (which may denote time,
space, or whatever else one wishes). A more intuitive definition
might call this the set of all possible outcomes of an experiment
(this set also being called the ensemble)
inherently involving some degree of randomness along with the
mechanism by which individual outcomes, or
- Acronym for Study of Tropical Oceans in Coupled Models, a project for the
intercomparison of tropical ocean behavior in coupled
ocean-atmosphere models on seasonal and interannual
scales. It focuses on the Atlantic and Indian Ocean
regions and their relationship to the Pacific Ocean.
This project is designed to be complementary with
the ENSIP program.
- Stokes drift
- A mean Lagrangian current that can be generated by surface gravity
waves. This is caused when water particle orbits are not closed in
surface gravity waves. A steady drift results even if no mean
currents are present.
See Stokes (1847) for the original work and
McWilliams and Restrepo (1991) for a review of possible effects
on ocean circulation.
See also Ianniello and Garvine (1975).
- Stokes' theorem
- A theorem of geophysical importance in that it enables one to
calculate whether there is a tendency for a flow to be circulating
around a curve , e.g. the Earth.
It is mathematically expressed as
where is the normal vector to a surface , the
tangent vector to the curve bounding , and the
velocity vector field.
This theorem, dealing with the integration of the curl
of the velocity field (or, equivalently, the
vorticity vector), allows us to evaluate
whether or not the fluid is circulating (as well as rotating or spinning
via the calculation of the vorticity vector
See Dutton (1986).
- Stokes velocity
- A velocity in fluids that derives from the wave Reynolds stresses.
See the Stokes wave entry
and compare to
Lagrangian velocity and
See Wunsch (1981), p. 345.
- Stokes wave
- A wave theory whose theoretical development is the same as
that for Airy waves except that
second and higher order terms involving the wave height are
retained. The expression for the wave surface elevation includes
the Airy wave expression as the first term and a number of
additional terms (depending on the order of the theory) that
modify the elevation profile. The added terms generally
enhance the amplitude of the wave crest and detract from the
trough amplitude such that the crests are steeper and the
The particle orbits in Stokes theory, unlike those in
Airy wave theory, are not closed. This leads to a nonperiodic
drift or mass transport in the direction of wave advance
with an associated speed called the Stokes velocity.
Stokes wave theory is generally limited in applicability to
waves with steepness (i.e. where is the wave height
and the length) less than 1/100 in deep water, with even
more severe restrictions in shallow water.
See Komar (1976) and LeMehaute (1976).
- Stommel, Henry Melson (1920-1992)
- A physical oceanographer who has been called "the most significant
scientific contributor to the development of oceanography", Stommel's
long and distinguished career was marked not only by many significant
scientific contributions to his field but also
by his unsurpassed ability to help others in their research efforts
and to catalyze the development of major research programs.
His scientific contributions included proposing the use of T-S
correlations to estimate missing salinity values from measured
temperatures in order to calculate dynamic heights, the beta spiral
method for determining absolute geostrophic circulation fields,
the initiation of studies of double diffusion, and the development in
the early 1960s
(along with Arnold Arons) of a model of abyssal circulation
that still serves as the fundamental basis for further
His most famous contribution was his 1947 paper in which he
developed an analytical model showing how the westward intensification
of ocean currents is caused by the variation of the Coriolis
parameter with latitude (i.e. the beta effect).
His efforts to foster research programs included the genesis
of the long-term measurements of the deep waters off Bermuda in
1953, the planning (with K. Yoshida) of a survey of the
Kuroshio Current in the late
1960s, the proposal of a dense network of oceanographic stations
off the coast of Bermuda that resulted in the
Mid-Ocean Dynamics Experiment (MODE),
and the motivation of the geochemistry community to carry out
the GEOSECS program.
His work led to hundreds of publications under his name and
with dozens of collaborators.
His books included
Science of the Seven Seas (1945), The Gulf Stream (1966),
Kuroshio (co-edited with K. Yoshida in 1972),
Volcano Weather (co-written with his wife Elizabeth in 1983),
Lost Islands (1984), A View of the Sea (1987) and
Introduction to the Coriolis Force (co-written with Dennis
Moore in 1989). He inspired the 1981 festschrift entitled
Evolution of Physical Oceanography: Scientific Surveys in
Honor of Henry Stommel (edited by B. Warren and C. Wunsch).
The Collected Works of Henry M. Stommel (edited by
N. Hogg and R. Huang) were published in three volumes in 1995.
This set includes introductory essays for each chapter written
by his many colleagues as well as previously unpublished
material, e.g. about a hundred pages from his unpublished
See Veronis (1992), Warren and Wunsch (1981),
and Hogg and Huang (1995).
- Stommel-Arons thermohaline circulation
- A model of global thermohaline circulation developed by
Henry Stommel and Arnold Arons
in a series of papers starting in 1961.
This model combines sources of abyssal water at either pole,
the turbulent mixing of warm surface water downward, the
broad and slow upward flow of cold deep water, and deep
western boundary currents in a dynamically consistent manner
to provide a first-order explanation for that part of the
general ocean circulation driven by spatial differences in
the salinity, temperature and, therefore, density of
- Stommel's demon
- In the theory of the
a deepening mixing layer allows only a narrow range of density
to subduct at any geographical location. Only water of a particular
density class is able to enter the thermocline at a given position.
Stommel likened the process to the role of the demons in Maxwell's
theory of gases. This has led to referring to the selection process
of subducted density as Stommel's demon.
See Stommel (1979),
Williams et al. (1995) and
- storm surge
- A phenomena wherein sea level rises above the normal tide level
when hurricanes or tropical storms move from the ocean along
or across a coastal region.
Technically, this is defined as the difference between the actual sea
(tide) level under the influence of a meteorological disturbance
(storm tide) and the level which would have been reached in the
absence of the meteorological disturbance.
This sea level rise can consists of three components, the
first of which results from low barometric pressure, i.e.
the so-called inverse barometer effect, where lower atmospheric
pressure on the surface of the water allows it to rise.
The second component is wind set-up where the winds drag
surface water to the shore where it piles up. The third
component of the rise is due to coupled long waves where the
peak of the wave coincides with the shoreline.
See Wiegel (1964) and Heaps (1967).
- Strait of Gibraltar
- A shallow strait that separates the eastern Atlantic Ocean
See Gascard and Richez (1985).
- Strait of Hormuz
- A strait joining the
Persian Gulf to the west and
the Gulf of Oman to the east.
It is located at about 56 E and 27 N.
- Strait of Magellan
- According to Strub et al. (1998), ``Despite the strong
southwesterly winds characteristic of the area, tides are the dominant
forcing function for the currents, especially on the Atlantic side.''
See Medeiros and Kjerfve (1988) and
Panella et al. (1991).
- Strait of Messina
- A narrow strait between between the southwestern tip of Italy and
Sicily that connects the
Tyrrhenian Sea in the north with
the Ionian Sea to the south.
It is a narrow channel whose smallest cross-sectional area
is 0.3 km in the sill region where the mean water depth is
80 m. The depth increases more rapidly in the southern than
in the northern part, with the depths 15 km from the sill to
the north and south being 400 m and 800 m, respectively.
Both Tyrrhenian Surface Water (TSW)
and Levantine Intermediate Water (LIW)
are present year-round, separated at a depth of around 150 m.
A seasonal thermocline is also present for most of the year with
the difference across this interface generally much larger than than
across the TSW/LIW boundary.
Large gradients of tidal displacements are present despite generally
small tides in the Mediterranean since the predominantly diurnal
tides to the north and south are approximately in phase opposition.
The tides combine with the topographic restrictions to allow current
velocities to reach as high as 3.0 m s in the sill region.
There is also a weak mean exchange flow directed toward the Ionian
Sea with a velocity of about 0.10 m s in the surface layer,
and toward the Tyrrhenian Sea at about 0.13 m s in the lower
See Bignami and Salusti (1990).
- Straits of Sicily
- A strait located at around 12 E in the
that separates the eastern and western basins.
Its shallow sill separates the deep waters of the
Tyrrhenian Sea to the northwest
from those of the
Ionian Sea to the southeast.
See Fairbridge (1966).
- In oceanography, the vertical density structure resulting from
a balance among atmospheric heating, surface water exchange,
freezing, stirring and diffusion of heat, and the horizontal
and vertical motion (advection) of waters with different
temperature and salinity characteristics.
- stratified estuary
- One of four principal types of estuaries
as distinguished by prevailing flow conditions.
This type is stratified with a
halocline between the upper and lower
portions of the water column of nearly constant salinity.
The James and Mersey estuaries are examples of this type.
- stratified fluid
- See Fernando (1991).
- stream function wave theory
- A surface gravity wave theory wherein the wavelength ,
coefficients , and the the value of the stream function
on the free surface are numerically determined
given the wave height , the water depth and the
wave period . The expression for the stream function
in a reference frame moving with the speed of the
The unknowns are determined to best satisfy the dynamic
free surface boundary condition in the least squares sense.
The advantages of this wave theory are that it is one theory
that can be applied to the full range from shallow to deep
water and from small to breaking wave heights, and that
fairly comprehensive tables are available for design
purposes (and, more recently, computer programs).
The original irrotational version of the theory has been
extended to some rotational flows. Other representations
in terms of the stream function or velocity potential have
also been developed since the stream function theory was first
described in 1965.
See Dean (1990).
- streaming velocity
- A small first-order mean velocity near the bottom in the direction
of wave motion that occurs in the presence of the vortical bottom boundary
layer in water of finite depth.
See Phillips (1977) and
- strength of ebb
- In the description of tides, the magnitude of the
ebb current at the time of
maximum speed. This is usually associated with lunar
tide phases at spring tides near perigee or with
maximum river discharge.
This is also known as ebb strength.
- Acronym for Sediment Transport Events over Shelves and Slopes.
See Sherwood et al. (1994).
- Acronym for Storm Transfer and Response Experiment, a joint
meteorological-oceanographic experiment carried out in the northwestern
Pacific Ocean during November and December 1980.
The purpose was to examine the response of the atmospheric and oceanic
boundary layers to the passage of storms.
See Fleagle et al. (1982),
Paduan and DeSzoeke (1986) and
- Strouhal number
- A dimensionless number
or parameter proportional to the reciprocal
of vortex spacing. It is expressed as a number of obstacle parameters
and generally used in momentum transfer calculations, e.g. Von Karman
vortex street and unsteady flow calculations.
It is expressed as:
where is a frequency, a characteristic length scale, and
a characteristic velocity.
- Acronym for Submersible System Used to Assess Vented Emissions, an
integrated instrument system consisting of an advanced chemical
analyzer and an array of physical property sensors.
SUAVE is used to investigate the chemical properties of hydrothermal vents.
The chemical analyzer is based on the principles of flow analysis
and colorimetric detection, and its main components include:
- a 12-channel peristaltic pump allowing the simultaneous operation of
up to four of the chemical methods employed;
- three miniature 3-way pinch valves to allow selection between
sample intake and up to three in situ standards;
- 8 reagent reservoirs and 4 standard reservoirs, with an auxiliary
bin with a 12 bottle capacity for extended deployments;
- an intake filter to prevent clogging of the sample intake, and manifolds
for mixing samples before testing; and
- six LED-photodiode detector channels.
The auxiliary sensors include:
- a CTD including an SBE 4 conductivity sensor
and an SBE 3 temperature sensor;
- a Sea Tech 25 cm transmissometer and a Sea Tech LS6000 Light
Scattering Sensor; and
- glass enscapsulated thermisters.
SUAVE was built in 1991 and has been deployed over 200 times to date,
accumulating more than 1500 hours of in situ analysis time, all
directed toward hydrothermal vent research. Over 1000 km of ridgecrest
with hydrothermal plumes have been investigated, with the thermochemical
attributes determined with spatial detail seldom achieved anywhere on
the sea floor.
See Massoth et al. (1992).
- Subantarctic Front
- In physical oceanography, a region of rapid transition in the
Southern Ocean (S)) between the
Polar Frontal Zone (PFZ) to the south and
the Subantarctic Zone (SAZ) to the north.
Its position is generally identified by the rapid northward sinking of the
salinity minimum associated with the
Antarctic Intermediate Water
(AAIW) from near the surface in the PFZ (S 34) to depths greater
than 400 m in the SAZ (S 34.30). The property indicators within
the front are S 34.20 at Z 300 m, 4-5 at
400 m, and O 7 ml/l at Z 200 m.
The SAF is one of three distinct fronts in the
Current (ACC), the others being
(to the south) the
Polar Front (PF) and the
Southern ACC Front (SACCF).
This has also been called the
sf Australasian Subantarctic Front.
See Orsi et al. (1995).
- Subantarctic Mode Water (SAMW)
- In physical oceanography, a water mass
in the Subantarctic Zone
of the Southern Ocean.
This is one type of
Subpolar Mode Water.
The SAMW is the deep surface layer of water with uniform temperature
and salinity created by convective processes in the winter. It can
by identified by a temperature of around -1.8 C and a salinity
of around 34.4 and is separated from the overlying surface water
by a halocline at around 50 m in the summer.
Although it is not considered to be a water mass,
it contributes to the Central Water
of the southern hemisphere, and is additionally responsible for the
formation of AAIW in the eastern part of the
south Pacific Ocean. This has also previously been called
See McCartney (1977), Piola and Georgi (1981)
and Tomczak and Godfrey (1994).
- Subantarctic Surface Water (SSW)
- A water mass found in the
Southern Ocean between the
Subtropical Front (STF) and the
Subantarctic Front (SAF) and
above the salinity minimum of the
Antarctic Intermediate Water (AAIW).
At the surface the SSW is fresher than the surface waters of the
Polar Frontal Zone (PFZ) in the
Drake Passage, although by the time
it reaches the Greenwich Meridian surface salinities are 0.3-0.4 higher
than in the Drake Passage and more saline than those in the
Below the surface the SSW shows monotonically decreasing temperature
as well as a maximum in salinity and a minimum in oxygen, both of the latter
induced by the underlying AAIW.
See Whitworth and Jr. (1987).
- Subantarctic Upper Water (SAUW)
- In physical oceanography, a
water mass located in the
Subantarctic Zone of the
Southern Ocean. It is characterized
hydrographically by temperatures ranging from 4-10 C in the
winter and 4-14 C in summer, with salinities between 33.9 and
34.9 and reaching as low as 33.0 in the summer as the ice melts.
See Tomczak and Godfrey (1994), p. 82.
- Subantarctic Zone
- The name given to the region in the
between the Subantarctic Front to
the south and
the Subtropical Front to the north.
This zone is characterized by the presence of
SAUW at and near the surface.
The SAZ is one of four distinct surface water mass regimes in the
Southern Ocean, the others being (to the south) the
Polar Frontal Zone (PFZ), the
Antarctic Zone (AZ) and the
Continental Zone (CZ).
See Tomczak and Godfrey (1994) and
Orsi et al. (1995).
- Subarctic Intermediate Water (SIW)
- In physical oceanography, this is a water
which originates from the Polar Front
formed between the Kuroshio
and the Oyashio in the western
North Pacific Ocean. It is formed chiefly by the process of mixing
of surface and deeper waters and subducted
into the subtropical gyre, filling
the northern Pacific south of 40 N from the east. This is one
of the few water masses whose formation process has little to do
with atmosphere-ocean interaction. It is characterized by a salinity
minimum ranging from about 300-1000 m depth and a large east-west
salinity gradient in the South Pacific.
See Tomczak and Godfrey (1994) (p. 161) and
- In physical oceanography, a process whereby
Ekman pumping injects surface water
into intermediate depths along isopycnal
surfaces. This process is responsible for the formation of the
water masses in the permanent thermocline.
Although it is a permanent process, water mass formation occurs only
in late autumn and winter due to variations in the seasonal
See Tomczak and Godfrey (1994).
- Subduction Experiment
- An experiment that took place in the subtropical North Atlantic near
the eastern flank of the Bermuda/Azores atmospheric high pressure
system from June 1991 to June 1993.
That region is a preferred one for convergence of the wind-driven or
Ekman circulation which leads to subduction, the process by which
mixed layer water is injected into the main thermocline.
See Spall et al. (2000).
- subjective analysis
- In meteorology, the name given to
synoptic weather charts prepared
by hand since the resulting diagnosis or analysis relied extensively
on the subjective judgment of the preparer.
Compare to objective analysis.
See Daley (1991).
- Subpolar Mode Water (SMW)
- See McCartney and Talley (1982).
- subsurface countercurrent (SSCC)
- Another name for the
Tsuchiya jets found in
the equatorial Pacific Ocean.
- Of the subtropics.
- Subtropical Convergence
- The name given by Deacon (Deacon (1933), Deacon (1937))
to the hydrographic boundary between the
Southern Ocean and
subtropical waters to the north. This was replaced by the
term Subtropical Front (STF)
in the mid-1980s.
- Subtropical Countercurrent
- An eastward flowing current found in the region from 20-26 N.
In geostrophic current calculations
these currents extend to the bottom of the thermocline and occasionally
to 1500 m, while they've been identified in ship drift data with
speeds reaching 0.15 m/s. They do not exist east of Hawaii and,
given also the fact that they are in the middle of the subtropical gyre,
are thought to be caused by a modification of the Sverdrup
circulation by those islands. No satisfactory explanation has as
yet been advanced.
See Tomczak and Godfrey (1994) and
Kubokawa and Inui (1999).
- Subtropical Front (STF)
- In physical oceanography, a region of pronounced meridional
gradients in surface properties that serves as the boundary between
the Southern Ocean and the waters of
the subtropical regime
to the north. This was originally called the
Subtropical Convergence (DTC)
by Deacon but the newer terminology arose in the mid-1980s.
This is generally a subduction
region for various types of
The STF separates the
Subantarctic Surface Water
(SASW) to the south from the
Subtropical Surface Water
to the north.
The surface hydrographic properties
of the STF include a rapid salinity change from 35.0 to 34.5 and
a strong temperature gradient (from 14-10 C in winter and
18-14 C in summer) as one crosses from north to south.
At 100 m its approximate location is within a band across which
temperatures increase northward from 10 to 12 C and salinities
from 34.6 to 35.0, with the salinity gradient usually the more
The position as well as the intensity of sinking or rising motion in
the STF is more variable than in any other front or divergence in
the Southern Ocean.
See Tomczak and Godfrey (1994), Tchernia (1980) and
Orsi et al. (1995).
- Subtropical Frontal Zone (STFZ)
- A broad zone up to 4-5 latitude wide consisting
of several cores or fronts interspersed by zones of relatively
homogeneous waters. The STFZ is thought to be a more accurate
desciption of what was formerly thought to be single front
called the Subtropical Front, with
the STFZ boundaries being the North Subtropical Front (NSTF)
and the South Subtropical Front (SSTF).
See Belkin and Gordon (1996).
- subtropical gyre
- A clockwise/counterclockwise circulation in the northern/southern
hemisphere that is forced by the wind and features western intensification
in the form of a western boundary current. In the northern
hemisphere the gyres span the width of the oceans and extend from about
10 to 40 N with the boundary currents in the Atlantic
and Pacific called, respectively, the Gulf Stream and the Kuroshio.
There are analogous features in the southern hemisphere.
The polar boundaries between these and the
subpolar gyres coincide with
the latitude at which the curl of the wind
stress vanishes, the latter being largely the mechanism of causation.
See Schmitz and McCartney (1993).
- Subtropical Mode Water (STMW)
- A type of water mass found along the
equatorward side of the separated western boundary currents of each
of the subtropical gyres.
They are identified as a layer of reduced stratification found below
the seasonal thermocline and above the main thermocline.
They are formed by winter mixing and cooling, with restratification
occurring in the surface layer during summer.
The STMW thermostads can be traced for a considerable distance away
from the formation regions following the equatorward flow of the
In the North Pacific, deep convection occurs offshore of both the
Kuroshio and the Kuroshio Extension in winter.
Vertically homogeneous water is formed in the deep convective
mixed layer which remains as a pycnostad between the seasonal
and main thermoclines through the succeeding surface warming.
This pycnostad is found over a much wider region in the western
subtropical North Pacific than its formation area, and the
water therein is the North Pacific STMW.
According to Suga and Hanawa (1995):
composing the Kuroshio recirculation system advects STMW formed in
the wintertime thick mixed layer immediately off the
Kuroshio Current and the
During the non-large-meander period, the recirculation system
has a single anticyclonic gyre centered near 30N, 137E and
advects STMW formed off the
Kuroshio Extension, or east of 140E, to the meridian of
137E south of Honshu within a few months.
Heavier STMW formed farther eat is advected along an outer path, taking
several months longer.
During the large-meander period, the recirculation system is separated
into two anticyclonic gyres west and east of 140E, and no
substantial westward advection of STMW across the 140E meridian
occurs, while minor advectionof STMW along the outer path can occur.
The climatological hydrography also suggests that the STMW formed in one
winter will be dissipated considerably within a year or so.
In the South Pacific, the STMW thermostad is less pronounced than in
either the North Pacific or North Atlantic.
According to Roemmich and Cornuelle (1992), the South Pacific STMW ...
... is a thermostad, or minimum in stratification, having temperatures
of about 15-19C and vertical temperature gradient less than
about 2C per 100 m. Typical salinity is 35.5 psu at 16.5C.
The STMW layer is formed by deep mixing and cooling in the
eastward-flowing waters of the separated
East Australia Current (EAC).
Surface mixed layers are observed as deep as 300 m north of New Zealand
in winter, in the center of a recurring anticyclonic eddy.
See Masuzawa (1969),
Roemmich and Cornuelle (1992),
Hanawa and Suga (1995),
Suga and Hanawa (1995) and
Hautala and Roemmich (1998).
- Generally the part of the Earth's surface between the tropics and
the temperate regions, or between about 40 N and S.
- Sulawesi Sea
- Part of the
Australasian Mediterranean Sea centered at approximately
122 E and 3 N. It is surrounded by the Sulu
Archipelago and Mindinao to the north, Kalimantan to the
west, the Makassar Strait
and Sulawesi to the south, and the north part of the
Moluccan Sea to the west.
It covers about 280,000 sq. km with the deepest part being
around 6200 m just southwest of Mindanao. The entire Sulawesi
is mostly a deep, flat (4600-5200 m deep)
plain with steep sides.
The deep water Pacific Ocean water that passes through
the northern Molucca Sea and
enters the Sulawesi over a 1400 m deep sill. This water
eventually passes through the Makassar Strait and on into
the Flores Sea to the south.
The surface temperatures range between 28 C in
April and 27 C in February, and the salinities range
through four patterns during the year (i.e. 31-34 from SW to NE during
Dec.-Feb., 32.8-33.9 from SW to NE during Mar.-May, 34 from
Jun.-Aug., and 33.5-34.1 from NW to SE during Sep.-Nov.).
The monsoon pattern dominates the wind forcing, with the
winds blowing from the north to northeast during the northern
winter and more weakly from the south and southwest during
the summer. This creates a surface current directed from
Mindanao towards the Makassar Strait during the summer.
This regime is largely maintained through the winter although
westward currents are additionally found along Sulawesi.
See Fairbridge (1966).
- Sulu Sea
- A regional sea contained within the
Australasian Mediterranean Sea at the southwestern edge of
the Pacific Ocean.
It is centered at about 120 E and 8 N
and connected to the
Sulawesi Sea to the southeast
via many passages through the Sulu Archipelago, the
Bohol Sea to the east, and
the South China Sea to the
west and northwest chiefly via the Mindoro, Linapacan,
North Balabac, and Balabac Straits. It borders the Philippine
islands of Mindanao, Negros, and Panay to the east, Mindoro
and the Calamin Group to the north, Palawan to the west,
and the aforementioned Sulu Archipelago to the southeast.
The Malaysian portion of the island of Borneo lies to the
- A squall that occurs in the Malacca Strait, blowing from between
southwest and northwest. These usually occur at night and are
most frequent between April and November. They are generally
accompanied by thunder and lightning and torrential rain, and
their arrival is accompanied by a sudden fall of temperature.
- Sunda Sea
- A marginal sea in the southwest Pacific Ocean. This is a name
sometimes given to the combined areas of the
Java Sea and the
shelf sector of the
South China Sea.
- Sunda Shelf
- One of the largest continental shelves in the world.
It covers around 1,800,000 km, is centered around
108 E and 2 N, and occupies the regions
of the Java Sea,
the southern parts of the
South China Sea, and the
Gulf of Thailand.
See Fairbridge (1966).
- Acronym for Subarctic Pacific Ecosystem Research, a research program in
the north Pacific.
See Miller (1993).
- A French project to make systematic hydrographic observations in the
North Atlantic subpolar gyre.
Observations are made with the merchant ships Godafoss
(between Iceland and the U.S. sine 1993) and Nuka Arctica (between
Denmark and Greenland since May 1997).
The sampling is mostly for temperature with
XBTs and for sea surface salinity.
- surf beat
- The rising and falling of the water level in the surf zone
at intervals in the vicinity of 2 to 5 minutes, especially
noticeable on a flat beach. This is caused by the pattern
of incoming waves being such that groups of high waves and
low waves follow each other at the same intervals. This is
in turn due to the interaction of wave groups with slightly
different frequencies, a process that leads to a much longer
envelope or beat frequency modulated the short wavelength
See Wiegel (1964).
- surf zone
- The portion of the nearshore zone
in which borelike
translation waves occur following wave
breaking. It extends from the inner breakers shoreward to the
See Komar (1976).
- surface energy balance
- The balance of energy terms
at the ocean surface in a climate model. The terms are the
absorbed solar flux (S), the downward
infrared flux (Sd), the
upward infrared flux (Su), the
sensible heat flux (H), and the
latent heat flux (LE). The balance can
be expressed as
S + Sd - Su - H - HE = 0
- surface renewal theory
- A method for evaluating turbulent fluxes at the ocean surface.
See Clayson et al. (1996).
- surface Reynolds number
- See Kagan (1995).
- surface scattering layer
- A group of marine organisms in the surface layers of the ocean
which scatters sound. The layer may extend from the surface to
depths as great as 600 feet, and several layers or patches may
comprise the layer. There are also shallow and deep scattering
- surface tension
- More later.
- A French project started in the austral summer of 1992/1993 for
monitoring climate variability at high latitudes.
The objective of the program is to monitor the seasonal and interannual
changes in upper ocean thermal content and salinity, as well as changes
in the position, structure and transport of the polar fronts between
Tasmania and Antarctica.
SURVOSTRAL uses the French Antarctic supply ship Astrolabe to make
measurements between Hobart, Tasmania and the French base
Sampling is performed with XBTs and
XCTDs to obtain vertical profiles of temperature
and salinity, and a thermosalinograph is used to obtain continuous
measurements of surface salinity and temperature.
- Abbreviation for
Subarctic Upper Water.
- Sverdrup, Harald Ulrik (1888-1957)
- Sverdrup started his scientific career by enrolling as
a student in ``physical oceanography and astronomy'' at the
University of Oslo, where his early interests leaned towards
the latter. This changed when he received an assistantship
to study under Professor V. Bjerknes, under whom he published
twenty papers and a dissertation entitled Der
nordatlantische Passat (in which he calculated energy and
momentum budgets for the North Atlantic trade winds) over
the next six years.
He took charge of scientific work on Roald Amundsen's North
Polar expedition at the age of 29 in 1918. He did not return
until late in 1925 as the expedition ship Maud attempted
to duplicate the voyage (and ice drift) of the Fram.
At one point during the seven years of this expedition Sverdrup
left the ship to spend eight months with the nomadic Chukchi
tribe of northeastern Siberia, an experience he later recounted
in a book (which has never been translated into English).
The collected observations of the expedition were a notable
achievement, with Sverdrup's most significant contribution
being a paper entitled ``Dynamics of tides on the North
Sverdrup succeeded V. Bjerknes as the Chair of Meteorology
at the Geophysical Institute in Bergen, Norway upon his return,
and he additionally became a research professor at the
Christian Michelson Institute in Bergen in 1931.
The ten years following his return from the Maud
expedition were the most productive of his career, with
his accomplishments including publishing over fifty papers
on results from the expedition, spending two half-year periods
in Washington, D.C. to help analyze the results from a cruise
of the Carnegie, taking charge of the scientific work
on the Wilkins Ellsworth North Polar Expedition aboard the
submarine Nautilus in 1931, and spending two months
in the snow fields of Spitzbergen which resulted in the
first quantitative heat budget of glaciers.
In 1936 he accepted the Directorship of the Scripps Institution
of Oceanography in La Jolla, California, leaving the Michelsen
Institute for three years, although the war resulted in his
not returning to Norway until 1948.
At Scripps Sverdrup initiated the Marine Life Research Program
(still ongoing today), organized the first systematic course
in oceanography given in the United States, and taught and collaborated
such future reknowned scientists as Gifford Ewing, Donald Pritchard,
Roger Revelle, Robert Reid and Walter Munk. He spent a great deal
of time and effort during the pre-war years collaborating with
Martin Johnson and Richard Fleming to write the classic
text The Oceans, with his chapter on the water masses and
currents of the oceans still one of the best reviews of the
He returned to Norway in 1948 at the age of sixty and retired
from research, dividing his time variously as Director of the Norsk Polar
Institut, the President of the ICES,
Prorector and Director of the Summer School for foreign students
at the University of Oslo, and as Chairman of a committee for
reorganizing the Norwegian educational system. He continued
in these activities until a stroke weakened him and led to his
death in 1957.
- A unit of transport used in oceanography equivalent to
ms and abbreviated as Sv.
- Sverdrup balance
- A vorticity balance in which meridional advection in the presence
of the planetary vorticity gradient is balanced by the stretching
of fluid columns. It is most simply stated as
where is the meridional gradient of
the Coriolis parameter ,
the meridional velocity, and the vertical velocity.
This indicates that the stiffness imparted to a large scale fluid by
planetary rotation leads to the conservation of the separation of
marked fluid surfaces measured parallel with the rotation vector.
- Sverdrup transport
- The net meridional flow of mass in the interior of the ocean
gyres away from the lateral boundaries.
- Abbreviation for Surface Velocity Program, a
- Swallow float
- See Swallow (1955).
- swamp ocean
- The simplest ocean model used in coupled model
simulations. SSTs are computed but from
surface energy balance
(local effects) only, i.e. there is no accounting for
heat storage (temporal) or ocean current (nonlocal) effects.
Only mean annual forcing can be applied when a swamp ocean is
used since the lack of the capability to store heat in the
oceans would allow sea ice to freeze into the mid-latitudes
in the winter hemisphere. On the plus side, the dominant
equilibration time is that of the atmosphere since the ocean
surface response time is almost instantaneous.
- Acronym for Surface WAve Dynamics Experiment, an experiment
performed in the fall of 1990 off the coast of Virginia which
was primarily concerned with the evolution of the directional
wave spectrum, wind forcing and wave dissipation, the effect
of waves on air-sea coupling mechanisms, and the microwave radar
response of the ocean surface. The scientific goals were
to understand the dynamics of the evolution of the wave field
in the open ocean; to determine the effect of waves on the
air-sea transfers of momentum, heat and mass; to explore the
response of the upper mixed layer to atmospheric forcing;
to investigate the effect of waves on the response of various
airborne microwave systems; and to improve numerical wave
See Weller et al. (1991) and
- 1. Acronym for Sea Wave Modeling Project.
See group (1985).
2. Acronym for
Southwest Area Monsoon Project.
- Acronym for Simulating WAves Nearshore, a third-generation
that computes random, short-crested, wind-generated waves in coastal
regions and inland waters. The physics accounted for in the SWAN
A copy of the FORTRAN code is available upon registration.
See Booij et al. (1999).
- wave propagation in time and space, shoaling, refraction due to
current and depth, frequency shifting due to currents, and nonstationary
- wave generation by wind;
- three- and four-wave interactions;
- whitecapping, bottom friction, and depth-induced breaking;
- wave-induced setup;
- propagation from laboratory up to global scales; and
- transmission through and reflection from obstacles.
- Acronym for Surface WAve Processes Program, an experiment
conducted off the coast of California in 1990 and concerned
with wave breaking and the interaction between surface waves
and upper ocean boundary layer dynamics. The scientific
goals were to improve the understanding of processes involved
in wave breaking (e.g. what determines the occurrence of breaking
in space and time, the processes of bubble and fluid injection,
the generation of turbulence in the upper layer of the ocean
by waves) and in determining the structure of the upper
ocean (e.g. the role of surface waves in air-sea transfers
and in mixed layer dynamics, with particular emphasis on the
structure and dynamics of
See Weller et al. (1991).
- Acronym for Shallow Water Acoustic Random Media 1995 experiment,
an ONR sponsored joint operation between the NRL Acoustic
Signal Processing Branch and Woods Hole. The goal is
to explore the effects on acoustic propagation of random
ocean environments in the water column and the bottom
sediments. The experiment was performed on the continental
shelf about 100 miles of the coast of New Jersey in the
Hudson Canyon area in July-August 1995, and deployed
a significant number of acoustic and oceanographic
equipment to characterize the acoustic propagation
- swash zone
- The portion of the nearshore zone
in which the beach face is alternately covered by the uprush of
wave swash and exposed by the backwash.
See Komar (1976).
- Swedish Deep Sea Expedition
- A research cruise taking place from 1947-1948 aboard the
The expedition was headed by
Hans Pettersson who also edited the
ten-volume series of research reports published starting in 1957.
The contents of the reports were:
See Guberlet (1964).
- The ship, its equipment, and the voyage
- Physics and chemistry
- Bottom investigations
- Sediment cores from the East Pacific
- Sediment cores from the West Pacific
- Sediment cores from the North Atlantic Ocean
- Sediment cores from the Mediterranean Sea and the Red Sea
- Sediment cores from the Indian Ocean
- Special investigations
- Acronym for Shallow Water Intercomparison of wave prediction
Models, and extension of the
SWAMP project to shallow water.
See group (1985).
- Acronym for Shallow Water Integrated Mapping System, an instrument
developed by the APL.
- Acronym for Surface Waves Investigation and Monitoring from SATellite,
a project to design, develop and use systems to measure directional
wave spectra from satellites using the real-aperture technique
rather than the traditional SAR technique.
The system is a dual-beam radar (capable of nadir viewing and
off-nadir viewing at an angle of 10) operating in the
K frequency band (13.565 GHz) and flying on a polar-orbiting
satellite at an altitude of 450-600 km.
The nadir beam is operated to measure significant wave height
and wind speed in the same way as spaceborne altimeters.
An innovative feature is its operation in off-nadir viewing mode
by tilting the radar beam to measure wave spectral characteristics.
The principle is based on measuring modulations of the radar
backscatter coefficient inside the swatch covered by the tilted
beam. The tilted beam is rotated to perform a conical scan around
the vertical axis to acquire measurements in all directions of
SWIMSAT should be capable of measuring wave spectral properties
under wind-sea (provided the dominant wavelength is greater than
about 70 m) and swell conditions (provided the significant wave
height is greater than 1.5-2 m, depending on wind).
See Hauser et al. (2001).
- Acronym for Slope Water Oceanic eDDY, a term coined in
Pingree and LeCann (1992) to describe jet-like extensions of
the slope current off northern Spain and France in the southern
Bay of Biscay in the winter that develop into anticyclonic eddies
with an upper core of slope water.
A typical SWODDY has a lifetime of about a year and, if not trapped
by topography, propagates or advects westwards out of the Bay of
Biscay at typical speeds of about 2 cm s.
- Abbreviation for southern warm tongue, a tongue of relatively warm
water located at the eastern boundary of the
WPWP. It is located at around 10 S.
See Ho et al. (1995).
- An experiment (also called ERS-SYMPLEX) carried out in the Sicily
Channel during April-May 1996 to compare sea level anomalies obtained
from ERS-1/2 and TOPEX/POSEIDON altimeters with in situ data.
A dense network (about 5 km spacing) of XBT and CTD casts were made
along all ERS-1/2 and TOPEX/POSEIDON tracks at the same time of each
- Acronym for the SYNoptic Ocean Prediction experiment, an observational
and modeling experiment designed to understand the physics governing
large amplitude meandering of the Gulf Stream
and the shedding and interactions of
rings east of Cape Hatteras to the
The moored instrument program consisted of four arrays:
Observations were made between 1987 and 1990.
- the Inlet Array near Cape Hatteras, consisting of 9 inverted
echo sounders (IES) and 5 deep current meters, and
designed to monitor the inflow conditions as the Gulf Stream leaves
the continental margin;
- the Central Array near 68W, consisting of 24 IESs (12 with
bottom pressure gauges) and 12 tall current moorings, each with four levels
(400, 700, 1000 and 3500 m) instrumented, with three having upward-looking
ADCPs above the topmost current meter;
- the East Array near 55W; and
- the 50W array.
A significant finding of SYNOP was the presence of strong, deep
cyclones and anticyclones beneath the Gulf Stream, with the spin-up of
the deep flow field occuring during the passage of the steep meander
crests and troughs of the Stream. Velocities at 3500 m were observed
to be as high as 35-40 cm s during the strong events.
See Tracey and Watts (1991).
- Descriptive of data simultaneously obtained over a large area.
- synoptic mean circulation
- In oceanography, the time-averaged flow field obtained in a coordinate
system whose axes are parallel and perpendicular to the instantaneous
axis of a particular strong current such as the Gulf Stream. This
coordinate system can and does change with time.
Compare to Eulerian mean circulation.
See Schmitz and McCartney (1993).
- systematic errors
- Stable errors
in model simulations that result from model deficiencies in the
component (e.g ocean and atmosphere) models alone, additive errors
from the component models after they are coupled, or errors that
are produced by the coupled interactions between imperfect
component models. Sometimes called climate drift. See