Lecture 1 – Why the Oceans Matter (Oceanography GEO 009)

Vocabulary flashcards summarizing the major terms and concepts introduced in Lecture 1 and course logistics for Oceanography GEO 009.

Oceanography

The scientific study of the ocean’s physical, chemical, biological, and geological properties and processes.

Paleo-oceanography

Branch of oceanography that reconstructs past ocean conditions using geological and chemical proxies.

Paleo-climatology

Study of Earth’s past climates based on evidence from natural records such as ice cores, sediments, and fossils.

Latitude

Angular distance north or south of the equator, measured in degrees from 0° at the equator to 90° at the poles.

Longitude

Angular distance east or west of the Prime Meridian, determined by comparing local time with a reference time.

Prime Meridian

The 0° longitude reference line running through Greenwich, England, used to measure east-west position.

Chronometer

Highly accurate marine clock developed in the 18th century to determine longitude while at sea.

Depth Sounding

Early method of measuring ocean depth with a weighted, distance-marked line lowered from a ship.

SONAR

Sound Navigation And Ranging; uses sound pulses and echoes to measure water depth and map the seafloor.

Multibeam Echosounder

SONAR system that emits multiple sound beams to map a wide swath of seafloor in high resolution.

Satellite Altimetry

Technique that measures sea-surface height via radar from satellites to infer seafloor contours.

Phytoplankton

Microscopic photosynthetic organisms that generate about half of Earth’s oxygen supply.

Carbon Sink (Ocean)

The ocean’s capacity to absorb and store nearly half of human-produced CO₂ emissions.

Hurricane

Large tropical cyclone forming over warm ocean waters, heavily influencing coastal weather.

Polynesian Navigation

Ancient Pacific voyaging using stars, winds, waves, and stick charts for open-ocean travel.

Stick Chart

Polynesian map of sticks and shells representing wave patterns and islands for navigation.

Eratosthenes

Greek scholar (c. 235–192 BCE) who created the latitude-longitude system and measured Earth’s size.

Ferdinand Magellan

Portuguese explorer whose expedition first crossed the Pacific and circumnavigated the globe (1519-1522).

HMS Endeavour

Captain James Cook’s ship that conducted detailed mapping and scientific exploration (1768-1771).

Ming Dynasty Voyages

15th-century Chinese expeditions under Zheng He that expanded trade and exploration across the Indian Ocean.

Depth Equation (V × T / 2)

Formula where depth equals sound velocity multiplied by half the SONAR round-trip travel time.

Average Ocean Depth

Mean depth of the global ocean—about 3.8 km (12,500 ft).

Mariana Trench

Deepest known part of the ocean, reaching roughly 11 km below sea level.

Challenger Deep

Lowest point in the Mariana Trench with pressures above 15,000 psi and depths over 10,900 m.

Ocean Surface Area

The ocean covers about 361 million km², roughly 70 % of Earth’s surface.

Average Ocean Temperature

Global mean seawater temperature of approximately 3.9 °C (40 °F).

1 Atmosphere (atm)

Standard sea-level pressure (14.7 psi), equivalent to the weight of a 10 m column of water.

Fathom

Traditional nautical unit of depth equal to 6 ft, used in early depth soundings.