Ocean Circulation and Gyres Overview

Ocean Circulation

• Oceans are vast, dynamic systems with constantly flowing water, ranging from small eddies to large currents and gyres.
• Circulation is driven by salinity and temperature differences, winds, Earth's rotation, and landmasses.
• Ocean gyres are large circular currents.
• Gyres are formed by surface winds and the Coriolis effect.
• The Coriolis effect deflects water flow clockwise in the Northern Hemisphere and counter-clockwise in the Southern Hemisphere.

Ocean Gyres

• Gyres have a significant impact on climate, distributing heat absorbed from the sun throughout the globe.
• The Great Pacific Garbage Patch is a notable example of a gyre's accumulation effect.
• There are five major ocean gyres: North Pacific, South Pacific, North Atlantic, South Atlantic, and Indian.
• The North Pacific Subtropical Gyre is the largest, covering approximately 20 million square kilometers and exhibiting four prevailing currents.

Wind-Driven Surface Currents

• Prevailing winds create surface currents, forming gyres, upwellings, and other patterns.
• Global wind patterns (Hadley cells) are driven by uneven solar heating; rising air near the equator creates global wind patterns.
• Three types of global winds: Trade winds, Prevailing Westerlies, and Polar Easterlies
• Upwelling is the upward movement of nutrient-rich bottom water to the surface, driven by wind blowing parallel to coastlines. Upwelling areas are often highly productive marine ecosystems.
• El Niño Southern Oscillation (ENSO) is a significant climate cycle influenced by wind patterns in the Pacific Ocean and can have far-reaching impacts.

Thermohaline Circulation

• Thermohaline circulation is a global ocean current driven by temperature and salinity differences in water, forming the "Global Oceanic Conveyor Belt."
• Colder, denser water sinks at the poles, while warmer water rises at the equator.
• Salinity variations affect water density; higher salinity leads to greater density.
• Thermohaline circulation helps distribute heat globally.

Ocean Currents and Climate

• Ocean currents significantly influence regional climates, moderating temperatures.
• Water's high heat capacity stabilizes coastal regions.
• Warm ocean currents can contribute to higher precipitation in some regions. Conversely, cold currents can lead to lower precipitation and cooler temperatures.
• Ocean currents are crucial to the planet's heat distribution and greatly affect climate patterns.
• Climate change can disrupt ocean circulation patterns by affecting temperature and salinity gradients.