Untitled Flashcards Set

Oceanography Study Guide

Ocean Zones

• Mixed Layer Zone (0-250m): The warmest ocean layer with the most sunlight. This zone supports the highest concentration of phytoplankton, crucial for marine ecosystems.

• Thermocline Zone (250-1000m): A transition layer where temperature decreases rapidly from about 22°C at the top to 6°C at the bottom. Sunlight fades significantly in this zone.

• Deep Water Zone (1000m and deeper): The coldest and darkest layer, with temperatures ranging from 6°C to 2°C. No sunlight reaches this zone.

Ocean Topography

• Continental Slope: The steep edge of a continental landmass where upwelling commonly occurs.

• Seamounts: Underwater volcanic mountains that have not reached the ocean surface.

• Abyssal Plain: A flat and deep region of the ocean floor, largely featureless and covered in sediment.

• Mid-Ocean Ridge: A chain of volcanic mountains formed by divergent tectonic plates.

• Volcanic Islands: Islands formed from volcanic activity, typically at convergent subduction zones or over hot spots.

• Continental Shelf: The shallow, submerged extension of a continent.

• Trench: A deep ocean depression formed at convergent subduction boundaries, marking the deepest parts of the ocean.

Seafloor Spreading

• Occurs at divergent plate boundaries, where magma rises to create new oceanic crust.

• Older oceanic crust is found farther from the mid-ocean ridge.

• The process records Earth’s magnetic field reversals in seafloor rock.

Salinity

• Typical ocean salinity ranges from 33-37 ppt (parts per thousand).

• Primary sources of oceanic salts include volcanic eruptions and river runoff.

• Dominant components: sodium (Na+) and chloride (Cl-), forming sodium chloride (NaCl), or table salt.

Ocean Currents

1. Surface Currents: Driven by global winds; warm currents transport heat from the equator to the poles, while cold currents move from the poles toward the equator.

2. Deep Ocean Currents: Driven by density differences due to variations in temperature and salinity.

3. Thermohaline Circulation: Also called the Global Conveyor Belt, this system links surface and deep currents worldwide.

Upwelling

• Occurs when deep, cold, nutrient-rich water rises to the surface.

• Enhances marine life, supporting phytoplankton and fish populations.

El Niño & La Niña

• El Niño: An irregular climate event that warms the Pacific Ocean, disrupts weather patterns, and halts upwelling near South America.

• La Niña: The opposite of El Niño, it strengthens trade winds, increases upwelling, and brings colder ocean temperatures.

Land & Sea Breezes

• Sea Breeze (Daytime): Land heats faster than the ocean, causing warm air to rise over land and cooler ocean air to move in.

• Land Breeze (Nighttime): Land cools faster than the ocean, warm air rises over the ocean, and cooler air from land moves out to sea.