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Ocean ventilation
Ocean ventilation is the process by which young surface waters are injected into the ocean interior, carrying heat, carbon, and oxygen into the deep ocean.
Ocean-bottom node
An ocean-bottom node (OBN) is a cable-free seismic receiver placed on the seafloor that records data autonomously on battery power and is retrieved for download, offering wide-azimuth imaging advantages.
Oceanic Anoxic Event 2
Oceanic Anoxic Event 2 (OAE 2) was an interval of widespread ocean deoxygenation at the Cenomanian–Turonian boundary, about 94 million years ago, during extreme global warmth.
Oceanic carbon cycle
The oceanic carbon cycle is the movement of carbon through the ocean, which holds about 40 times more carbon than the atmosphere and absorbs about a quarter of annual human CO2 emissions.
Oceanic climate
The oceanic climate, also called a marine or maritime climate, is a temperate climate type with cool summers, mild winters, and precipitation year-round, typical of western Europe and the Pacific Northwest.
Oceanic crust
Oceanic crust is the thin, dense basaltic layer beneath the oceans, formed at mid-ocean ridges and recycled at subduction zones, covering about 60% of Earth's surface.
Oceanic Niño Index
The Oceanic Niño Index (ONI) is a NOAA index identifying El Niño and La Niña episodes from sea surface temperature anomalies in the central equatorial Pacific.
Oceanic plateau
An oceanic plateau is a vast region of anomalously thick oceanic crust, typically over 200,000 km² in area, formed by mantle plumes; the largest is the Ontong Java Plateau.
Oceanographer
An oceanographer is a scientist who studies the ocean, including its processes, seawater, seafloor, and marine life. The field divides into biological, chemical, geological, and physical branches.
Oceanographic time-series cruise programs
Oceanographic time-series cruise programs are recurring shipboard expeditions that occupy the same deep-ocean station on a monthly schedule to measure water-column physics, chemistry, and biology over decades.
Oceanography
Oceanography, also called ocean science or marine science, is the study of the ocean, drawing on physics, chemistry, geology, and biology to cover seawater, marine life, currents, and the seafloor.
October 2010 Sumatra earthquake
The October 2010 Sumatra earthquake was a magnitude 7.8 thrust quake off the Mentawai Islands, west of Sumatra, on 25 October 2010; its tsunami killed several hundred people.
October 2021 Northeast Pacific bomb cyclone
The October 2021 Northeast Pacific bomb cyclone was an explosively deepening extratropical cyclone that struck the Pacific Northwest on October 24, 2021, reaching a record-low pressure of 942.5 mb.
Offset tracking
Offset tracking, also called pixel-offset tracking, is a synthetic aperture radar technique that measures surface displacement, used for glacier flow and large earthquake deformation where InSAR fails.
Offshore groundwater
Offshore groundwater is low-salinity water stored in sediments and rocks below the seafloor, first documented off Florida in the 1960s and estimated at about 1 million cubic kilometers globally.
Ogallala Aquifer
The Ogallala Aquifer, formally the High Plains aquifer, is a groundwater system underlying about 174,000 square miles of the Great Plains in eight states, supplying about 30 percent of US irrigation groundwater.
Oil and Gas Methane Partnership 2.0
The Oil and Gas Methane Partnership 2.0 is a UNEP framework, launched in 2020, under which oil and gas companies report methane emissions using measurement-based methods.
Oil sands
Oil sands, also known as tar sands, are geologic deposits of sand, clay, water, and bitumen so viscous it will not flow to a well, found chiefly in northern Alberta.
Oil shale
Oil shale, also known as kerogen shale or bituminous shale, is a sedimentary rock containing kerogen, a solid precursor of oil that converts to crude oil when heated.
Oil window
The oil window is the range of burial depth or thermal maturity within which a sedimentary source rock generates and expels liquid petroleum from kerogen.
Oklahoma Mesonet
The Oklahoma Mesonet is a network of 120 automated weather stations across Oklahoma, with at least one in each of its 77 counties, commissioned in 1994.
Okta
Okta, Inc. (Nasdaq: OKTA) is an American identity and access management company whose cloud platform authenticates users and governs their access to applications, serving organizations from small businesses to Fortune 500 companies.
Oku Volcanic Field
Oku Volcanic Field (Oku Volcanic Group), a volcanic field in northwest Cameroon on the Cameroon Volcanic Line; four stratovolcanoes culminating at Mt. Oku (3,011 m), activity 30 to <1 Ma, basanite-to-rhyolite lavas, and the Lake Nyos and Monoun CO2 disaster lakes.
Olca-Paruma
Olca-Paruma, a 15-km-long east-west chain of stratovolcanoes on the Chile-Bolivia border in the Central Andean Volcanic Arc; summit 5,705 m, only reported historical eruption an unconfirmed flank event in 1865-1867, now fumarolic and seismically monitored.
Old Red Sandstone
The Old Red Sandstone is a unit of continental red beds of late Silurian to early Carboniferous age, best exposed in Britain, Ireland, and lands around the North Atlantic.
Older Dryas
The Older Dryas was a brief cold stadial about 14,000 years ago that interrupted the Bølling–Allerød warming at the end of the last ice age, named for Dryas octopetala leaves in Scandinavian lake clays.
Oldest Dryas
The Oldest Dryas was the oldest of the three cold Dryas stadials of the European late glacial, spanning roughly 19,000 to 14,700 years before present and preceding the Bølling warming.
Oligocene
The Oligocene, from 33.9 to 23.03 million years ago, is the youngest epoch of the Paleogene Period, marked by global cooling, Antarctic ice sheet growth, and major mammal turnovers.
Oligotrophication
Oligotrophication, also called re-oligotrophication, is the decline of nutrient concentrations and productivity in an aquatic ecosystem, most often a deliberate result of cutting nitrogen and phosphorus inputs to a formerly eutrophic lake.
Olimpiada
Olimpiada (Олимпиада) is a gold mine in Krasnoyarsk region, Eastern Siberia, Russia, operated by PJSC Polyus and among the largest gold mines in the world.