751 articles
Antarctic Intermediate Water
Antarctic Intermediate Water (AAIW) is a cold, low-salinity water mass of the Southern Ocean, marked by a salinity minimum at 700–1000 m that spreads northward into all three ocean basins.
Aphotic zone
The aphotic zone is the part of the ocean below roughly 1,000 meters where sunlight does not penetrate, comprising the bathypelagic, abyssopelagic, and hadopelagic zones and lit only by bioluminescence.
Aquatic Sciences
Aquatic Sciences is a peer-reviewed Swiss journal covering limnology, hydrology, and aquatic research, published by Springer; it continues the Swiss Journal of Hydrology, founded in 1920.
Aqueduct 4.0
Aqueduct 4.0 is the 2023 version of the World Resources Institute's Aqueduct water risk framework, mapping 13 open-data indicators of water quantity, quality, and reputational risk worldwide.
Aquifer
An aquifer, also known as a groundwater basin, is an underground layer of soil or rock that stores groundwater and transmits it to wells, springs, and streams.
Aquitard
An aquitard is a saturated geologic formation of low permeability, usually clay, silt, or shale, that slows groundwater, confines aquifers, and allows slow vertical leakage between them.
Aragonite saturation state
The aragonite saturation state (Ωarag) measures how close seawater is to chemical equilibrium with aragonite, a form of calcium carbonate that marine organisms use to build shells and skeletons.
Argo (oceanography)
Argo is an international ocean-observing program that deploys nearly 4000 robotic profiling floats measuring temperature and salinity to 2000 m, supplying most subsurface climate data.
Armoring (stream)
Armoring (also spelled armouring) is the process by which a gravel-bed stream's surface becomes coarser than the underlying bed, measured by the armor ratio of surface to subsurface grain size.
Artesian well
An artesian well is a well drilled into an aquifer confined under pressure between impermeable layers, so water rises above the aquifer, sometimes flowing freely.
ASCAT (scatterometer)
ASCAT (Advanced Scatterometer) is a C-band real-aperture radar instrument flying on Europe's Metop satellites that measures wind over the global ocean, chiefly for weather forecasting.
Association for the Sciences of Limnology and Oceanography
The Association for the Sciences of Limnology and Oceanography (ASLO), formerly the American Society of Limnology and Oceanography, is an international scientific society for freshwater and marine researchers.
Atmospheric diving suit
An atmospheric diving suit, or ADS, is a tethered one-person submersible shaped like a suit of armor, keeping the operator at surface pressure to avoid decompression sickness.
Aufeis
Aufeis, also called icing or naled, is layered ice formed when groundwater overflows onto frozen ground or river ice and freezes, sometimes several meters thick, as in Siberia.
Australian Hydrographic Service
The Australian Hydrographic Service, also known as the Royal Australian Navy Hydrographic Service, is the Australian Department of Defence agency responsible for surveying and charting Australian waters, formed in 1920.
Autonomous underwater vehicle
An autonomous underwater vehicle (AUV), also called an autonomous undersea vehicle or autonomous submarine, is an uncrewed, untethered underwater robot that executes pre-programmed missions without operator control.
Available water capacity
Available water capacity (AWC) is the amount of water in soil that plants can take up, held between field capacity and the permanent wilting point.
Avalanche dynamics
Avalanche dynamics is the branch of snow science that studies how avalanches move and exert destructive force, from dense flowing slides to powder clouds, informing hazard maps.
Avalanche hazard assessment
Avalanche hazard assessment is the process of judging how likely, how large, and where avalanches threaten people, communicated as a five-level danger rating for an area and time.
Bacterioplankton
Bacterioplankton are bacteria and archaea suspended in the water column of oceans, estuaries, and lakes, which recover dissolved organic matter and drive nutrient cycling and carbon sequestration.
Bankfull discharge
Bankfull discharge is the water flow that completely fills a stream's active channel just before spilling onto the floodplain, and it is widely treated as the river's dominant channel-forming flow.
Barrier layer (oceanography)
A barrier layer in oceanography is a nearly isothermal water layer between the mixed layer and the thermocline, kept in place by a salinity gradient and limiting surface heat exchange.
Baseflow
Baseflow (also written base flow) is the portion of streamflow supplied by groundwater discharge and other slowly released stored water, sustaining rivers between storms and through dry seasons.
Baseflow recession
Baseflow recession is the decline of streamflow during dry periods, when groundwater and subsurface storage sustain the river, and it is used to estimate low flows and recharge.
Baseflow separation
Baseflow separation is a hydrological technique that splits a streamflow hydrograph into sustained baseflow and rapid quickflow, summarized by the baseflow index, the ratio of baseflow volume to total streamflow volume.
Bathymetry
Bathymetry, also known as seafloor mapping, is the study of the depths and shapes of underwater terrain, measured mainly with echo sounders and mapped with depth contours called isobaths.
Bathymetry mapping
Bathymetry mapping is the measurement and charting of seafloor depth, done from ships with sonar, from aircraft and satellites with lidar, or from satellites through gravity and optical methods.
Bathyscaphe
A bathyscaphe is a free-diving deep-submergence vehicle, invented by Auguste Piccard, using a gasoline-filled float for buoyancy; the Trieste carried the first humans to the ocean's deepest point in 1960.
Bathysphere
The Bathysphere was a tethered spherical submersible used by William Beebe and Otis Barton off Bermuda in the 1930s, reaching a record 923 meters in 1934.
Bedford Institute of Oceanography
The Bedford Institute of Oceanography, established in 1962 in Dartmouth, Nova Scotia, is Canada's largest center for ocean research, hosting over 600 staff from several federal departments.