Hydrology and ocean science

Storm surge

Storm surge, also called a storm flood or tidal surge, is an abnormal rise in seawater level during a storm, driven mainly by a storm's onshore winds.

Stream gauge

A stream gauge is an installation on a river or stream that continuously records water-surface height, called stage, from which the flow volume, or discharge, is computed.

Stream metabolism

Stream metabolism is the combined rate of organic-carbon production and consumption in a stream, measured as gross primary production, ecosystem respiration, and net ecosystem production.

Streamflow reconstruction is a paleohydrology method that uses tree-ring chronologies, calibrated against gauge records, to estimate annual river flows back over a thousand years, helping water managers assess drought risk.

Submarine groundwater discharge

Submarine groundwater discharge (SGD) is the flow of water from the seabed into the coastal ocean, combining fresh groundwater and seawater recirculated through coastal sediments.

Submersible

A submersible, or submersible craft, is a self-propelled underwater craft that carries personnel while operating below the surface and surfacing under its own buoyancy control.

Submesoscale ocean process

A submesoscale ocean process is an ocean current or circulation feature between mesoscale eddies and small-scale turbulence, with horizontal scales of roughly 1 to 10 km and time scales of hours to days.

Subtropical gyre

A subtropical gyre is a large rotating system of ocean currents in each ocean basin, clockwise in the Northern Hemisphere and counter-clockwise in the Southern Hemisphere.

Subtropical mode water

Subtropical mode water (STMW) is a nearly uniform-temperature upper-ocean water mass, typically 250 m thick, formed by deep winter convective mixing on the equatorward side of western boundary current extensions in subtropical gyres.

Surf zone

The surf zone is the nearshore region of the ocean where incoming waves break, extending from the breaker line to the beach; higher waves widen it.

Surface Energy Balance Algorithm for Land

The Surface Energy Balance Algorithm for Land (SEBAL) is a satellite image-processing method, formulated in 1998, that estimates actual evapotranspiration for every pixel of a satellite image and has been applied in more than 25 countries.

Surface runoff

Surface runoff, also known as overland flow or stormwater runoff, is the portion of precipitation, snowmelt, or irrigation water that flows overland toward streams, rivers, drains, or sewers.

Surface water

Surface water is water in open bodies on the land surface, such as lakes, rivers, and streams; it is the most visible part of the hydrologic cycle and most cities' source.

Survey vessel

A survey vessel, also called a survey ship, is a ship or boat fitted with sonar for measuring water depth and mapping the seafloor for nautical charts.

Surveying Ships' Squadron

The Surveying Ships' Squadron was the Royal Navy's organized flotilla of hydrographic surveying ships, the direct descendant of the Surveying Service founded in 1817 within the Admiralty's Hydrographic Department.

Sverdrup (unit)

The sverdrup (Sv) is a non-SI oceanography unit of volume transport equal to one million cubic meters per second, named for Norwegian oceanographer Harald Ulrik Sverdrup.

Swash

Swash is the sheet of water that runs up a beach after a wave breaks and flows back down; the strip of beach it moves over is the swash zone.

SWAT model

The SWAT model, or Soil and Water Assessment Tool, is a USDA river basin model that predicts how land management affects water, sediment, and chemical yields in watersheds.

SWAT+

SWAT+ (Soil and Water Assessment Tool Plus) is a public-domain watershed model simulating water quantity and quality from small watersheds to large river basins, developed by USDA-ARS and Texas A&M AgriLife Research.

Swell (ocean)

Swell, also called ocean swell, is a set of wind-generated ocean waves that have traveled out of their generating area, showing smoother, longer-period crests than wind waves.

SWOT (satellite)

SWOT (Surface Water and Ocean Topography) is a NASA and CNES satellite launched in December 2022 that makes the first global survey of Earth's oceans, lakes, and rivers.

Taam Ja' Blue Hole

The Taam Ja' Blue Hole is a submarine sinkhole in Chetumal Bay, Mexico, and the deepest known blue hole, measured to 423.6 meters with its bottom unreached.

Tara Oceans

Tara Oceans was a 2009–2013 oceanographic expedition aboard the 36 m schooner Tara that sampled plankton across the world's oceans, co-directed by Eric Karsenti and Etienne Bourgois.

Terrestrial water storage

Terrestrial water storage (TWS) is the sum of all water on a region's land surface and subsurface, from soil moisture and groundwater to snow, ice, lakes, and rivers.

Terrestrialization

Terrestrialization, also called infilling, is the process by which a lake or pond gradually fills with organic and mineral sediment until a peatland forms, one of the two main pathways of peatland initiation alongside paludification.

TEX86

TEX86 is a paleothermometer that reconstructs past sea surface temperature from archaeal membrane lipids preserved in marine sediments, applied to ocean temperatures across roughly 190 million years of Earth history.

The Oceanography Society

The Oceanography Society is an American nonprofit professional society founded in 1988, which publishes the open-access journal Oceanography and supports meetings like the Ocean Sciences Meeting.

Theory of tides

The theory of tides explains the sea's periodic rise and fall through the gravitational pull of the Moon and Sun, beginning with Newton in 1687.

Thermal pollution

Thermal pollution, or heat pollution, is water quality degradation caused by discharging water at a temperature different from the receiving body, most often heated cooling water from power stations.