Ocean Glossary


Acoustic-monitoring – using sound receivers on buoys or mounted to the bottom of the ocean to record noises made by marine animals or to detect animals (such as tunas and sharks) that have been tagged with a data storage tag which can communicate with the sound receivers

Advisory – meteorological information issued when actual or expected weather conditions do not constitute a serious hazard but may cause inconvenience or concern. Examples of weather advisories include small craft advisories or high wind

Ahupuaʻa – a traditional way of dividing land that is the basic unit of Hawaiian natural and cultural resource management; commonly, this would consist of a piece of an island from the mountains to the sea

Anthropogenic – human-induced or resulting from human activities; often used to refer to environmental changes, global or local in scale

Atmosphere – the air that surrounds the earth; the farthest outer edge of the atmosphere is about 1000 km above the surface of the earth, but if you were 100 km above the surface of the earth, 99.9999% of the atmosphere would be below you

Automated – to operate or control an instrument or piece of equipment using pre-programmed instructions; many of the instruments used in the observing system have automated sampling

Autonomous underwater vehicle (AUV) – a device that travels underwater, powered by batteries or fuel cells, and measure various ocean properties such as depth, temperature, and salinity

Bathymetry – the study of water depth and seafloor relief; a bathymetric map shows seafloor terrain as contour lines (called depth contours or isobaths)

Berm – change in slope on a beach marking the top of the foreshore and the seaward edge of the flat portion of the beach that is typically above the high tide level

Biomass – the amount of living matter (living organisms); this is expressed as weight per unit area or per unit volume

Cabled observatory – instruments that measure various chemical, physical and biological parameters are placed in the location of study (in the ocean) and connected to land with data cords and power cords

Cetacean – a mammal that belongs to the order Cetacea, for example whales, dolphins, and porpoises

Chlorophyll – a substance called a pigment that all plants contain that allows the plant to capture light energy; this pigment makes plants appear green

Circulation – movement of water within and between ocean basins

Climate – long term average and variability of weather

Climate change – a long term change in global and/or regional climate patterns (such as temperature, pressure, or winds) sustained over several decades or longer; climate change may be due to natural external forcings, such as changes in solar emission or slow changes in the earth’s orbital elements; natural internal processes of the climate system; or anthropogenic forcing

Coastal region – a region where ocean meets land; the region encompasses everything from the coastline all the way to the first major change in terrain topography that is not influenced by coastal processes

Coastal resilience – Coastal communities face extraordinary and growing risks from coastal storms, sea-level rise, erosion, water safety, and associated threats. This problem is compounded by growing populations and increasing investment in vulnerable lands. These risks can be greatly reduced by identifying the most hazardous and exposed coastal areas, preventing development of these dangerous places, building structures and infrastructure to withstand coastal hazards, redeveloping and withdrawing from vulnerable areas, and conserving natural environments that act as barriers and buffers to coastal threats. Unfortunately most communities are not taking the necessary steps to address these problems. The first step to building coastal resilience is to predict hazardous coastal processes and the areas of greatest exposure among our communities. We may not be able to stop or prevent coastal hazards, but we can decrease their impact by building community resilience.

Coral cover – how much of the bottom is covered with living coral

Currents – generally continuous and directed movement of water; currents can be generated from forces such as Earth’s rotation, wind, temperature and salinity differences, and gravitational pull of the moon acting on seawater

Ecosystem – a community of plants, animals, and microorganisms that are linked by energy and nutrient flows and that interact with each other and with the physical environment

Ecosystem stewardship – an ethic whereby citizens participate in the careful and responsible management of air, land, water and biodiversity to ensure healthy ecosystems for present and future generations

Erosion – any process that gradually wears away at solids; erosion can be caused by wind, water, or ice moving down-slope or by the action of microorganisms

Evaporation – change in a substance from a liquid to a vapor (gas); when water molecules in the ocean evaporate, salinity can be increased in a localized area

Fluorescence – the absorption of a certain wavelength (or color) of light and the re-emission of that light at a longer wavelength (a different color)

Forecast – estimating conditions in the future; this is a prediction based on experimental or environmental data, and/or models

Fringing reef – a coral reef that forms near the shoreline

Global warming – refers to a rise in global temperature near Earth’s surface

GPS (Global Positioning System) – a system of satellites and receiving devices used to compute the location of various places on Earth

Groundwater – the freshwater found beneath the Earth’s surface, usually in aquifers; often supplies water to wells and springs

Hurricane – a storm system characterized by low pressure in the center and thunderstorms with high winds and heavy rain that can produce flooding and other damage

Intertidal – the zone between high and low tide

Iridium phone network – a system that uses approximately 70 earth-orbiting satellites to allow voice and data communication around the world (including at the poles and on the ocean); in the planning stages for this system, it was proposed that 77 satellites were to be used—a number equivalent to the atomic number of Iridium (Ir)

Knot – a measure of speed that equals one nautical mile per hour (equivalent to 1.15 miles per hour); one nautical mile is nearly identical to one minute of latitude

Lithosphere – outer layer of Earth that may bend under the weight of a shield volcano

Marine debris – any type of manufactured or manmade material that enters the coastal or marine environment by a stream or outfalls, is tossed by beachgoers, or released from boats at sea

Model – an approximation or simulation of a real system that includes the essential variables of the system; models create predictions based on a given set of initial conditions

Nutrients – any substance required by an organism that cannot be synthesized by the organism and has to be obtained from an external source; some examples of nutrients are nitrogen, phosphorus, and iron

Ocean state – the condition of the ocean, for example, wave height and direction, water level, and circulation patterns

Overtopping – flow of water, by waves and or high water levels, over an embankment such as a beach berm, a dune, or a roadbed

Photosynthesis – the process plants use to convert water and carbon dioxide into food and stored energy; plants get energy to do this process by capturing sunlight using chlorophyll; photosynthesis produces oxygen and energy, and consumes carbon dioxide

Pollutant – a substance that negatively affects the physical, chemical or biological properties of the environment

Precipitation – liquid or solid water that falls to the surface of the Earth in forms such as rain, snow, or hail; precipitation that falls on the ocean can lower the salinity in a localized area

Reef crest – the sharp break in slope at the seaward edge of the reef flat

Reef flat – the shallow area between the shoreline intertidal zone and the reef crest of a fringing reef

Respiration – the process used by certain organisms (animals and bacteria, for example) to get energy; during respiration, organisms produce energy, carbon dioxide, and water and they consume organic matter (such as plants or other animals) and oxygen

Run-up – up rush of water on a coast driven by wave action

Salinity – the weight of salt (in grams, g) in a given mass of water (in grams, g); seawater has an average salinity of 35 g salt per 1000 g water, which equals 35‰ (read: “35 parts per thousand”); Practical Salinity Units (PSU) are often used to describe salinity: a salinity of 35‰ equals 35 PSU; because salinity is measured as “grams per grams” many oceanographers prefer a “unitless” description such as “35” rather than “35 PSU” or “35‰”

Satellite – an object that has been placed in Earth’s orbit; oceanographers use satellites for high-speed global communication of various types of information

Sea level – the average (mean) height of the ocean with respect to a reference surface; the reference surface is defined using complex measurements and calculations

Sea level rise – a rise in sea level caused by glaciers melting and ocean water warming due to greenhouse gases and global warming

Sea surface temperature (SST) – measure of heat contained in water at the surface of the ocean

Seiche – a standing wave (also called a stationary wave) in an enclosed or semi-enclosed body of water such as bays, harbors, and lakes; these waves can be triggered by tides, strong winds, atmospheric pressure changes, and other phenomena

Stewardship – see “Ecosystem stewardship”

Storm surge – a rise in sea level that results from low pressure systems and associated high winds

Stream gauge – a location along a stream where measurements of water flow (generally volume of water in a given amount of time) are made; the United States Geological Survey (USGS) maintains many stream gauges in the U.S.

Submergence – flooding of a coast due to combined effects of subsidence and sea-level rise

Subsidence – island sinking due to lithospheric flexure

Surf zone – area in the ocean between breaking waves and the shoreline

Swell – wind waves that are often created by storms thousands of miles away from the beach where they break and group together according to speed to travel long distances; swells are much more organized than locally generated wind waves

Trade winds – the predominant wind pattern in the tropics; air moves from high pressure areas (around 30°N and 30°S) to lower pressure near the equator; in the northern hemisphere, trade winds blow from the northeast

Tsunami – waves generated when a body of water is displaced; earthquakes, volcanic eruptions, landslides, and large meteoroid impacts have the potential to cause a tsunami; when these waves reach shallow coastal regions, amplitudes may increase to several meters; the Pacific Ocean is particularly vulnerable to tsunami

Upwelling – the rising of cold deep water to the surface of the ocean; the associated lowering of the sea surface temperature cools the atmosphere and modifies the local climate. The upwelled water is also rich in nutrients, and coastal upwelling regions are among the most important fishing regions of the World Ocean. The most important coastal upwelling regions are found in the eastern boundary currents of the subtropical gyres, that is, in the Peru/Chile, California, Benguela, and Canary Currents. The Somali, East Arabian, and South Java Currents develop upwelling on a seasonal basis.

Warning – issued when a hazardous weather or hydrologic event is occurring, is imminent, or has a very high probability of occurring; a warning is used for conditions posing a threat to life or property

Watch – issued when the risk of a hazardous weather or hydrologic event has increased significantly but its occurrence, location, and/or timing is still uncertain; it is intended to provide enough lead time so that those who need to set their plans in motion can do so

Water quality – the physical, biological and chemical characteristics of water

Wind – air in motion relative to the surface of the Earth

Wind waves – waves, on the surface of the ocean, generated by wind action; their dynamics are governed by the influence of gravity


American Meteorological Society; Southern California Ocean Observing System; Oceanography: An Invitation to Marine Science, 5th Edition, Tom Garrison, Brooks/Cole, a division of Thomson Learning, Inc., 2005; NASA; Gulf of Maine Ocean Observing System; Getting Involved in Caring for Hawaii’s Coastal Resources: A Community Guidebook; Coastal Wiki.

PacIOOS Outreach

If your organization, club, or community group is interested to learn more about PacIOOS' observation and forecasting tools, please contact us at info@pacioos.org. Our team appreciates the opportunity to share data tools with you and to collect feedback and input to enhance our program.