geol150 week 5 lecture 1

Chapter 1: Introduction

• Oceans and Earth's Surface

  • Cover over 70% of Earth's surface and are about 300 times the mass of the atmosphere.

  • Oceans play critical roles in storing resources and supporting life.

• Photosynthesis and Oxygen Production

  • Significant oxygen in the atmosphere is produced by oceanic organisms, specifically cyanobacteria (around 2.7 billion years ago).

  • Ocean ecosystems include a food chain: small organisms (like krill) feed larger fish, leading to apex predators such as sharks.

• Photic Zone

  • Ecosystems and photosynthesis occur primarily in the upper 100 meters of the ocean, known as the photic zone.

  • Light is essential for photosynthesis but is quickly attenuated as depth increases, creating limits for plant growth.

• Nutrient Requirements

  • Plants require water, light, and nutrients (like nitrogen, phosphates, potassium).

  • Nutrients have varying distributions, often limiting productivity in vast ocean areas.

• Nutrient Sourcing

  • Nutrients come from land (via river runoff) and from the deep ocean through upwelling processes, which are vital for supporting marine life.

Chapter 2: The Deep Ocean

• Ocean Movement

  • Ocean currents are driven mainly by wind and conducted by density differences (temperature and salinity).

  • Ekman Circulation: Water movement in response to wind creates spirals in the ocean depth, resulting in surface water moving at a 45-degree angle to wind, and deeper water moving at 90 degrees.

• Real-World Examples

  • Understanding ocean current patterns is vital for predicting impacts of events like oil spills.

  • Historical studies (like the Deepwater Horizon oil spill) illustrated how currents impact pollution spread and marine ecology.

Chapter 3: Surface of Ocean

• Coriolis Effect

  • The Earth's rotation affects current direction: in the Northern Hemisphere, currents are deflected right and left in the Southern Hemisphere.

  • Examples include the California Current, which brings nutrients from the deep ocean and supports diverse marine life.

• Trade Winds and Upwelling

  • Trade winds influence ocean currents, causing upwelling that brings nutrient-rich water to the surface, promoting photosynthesis and marine life.

Chapter 4: Surface of Ocean

• Ocean Gyres

  • Five major gyres exist on Earth's surface, notable for their sustainability and pollution accumulation (e.g., plastic islands).

  • Local currents, like the Gulf Stream, significantly impact weather and ecological systems across continents.

Chapter 5: Surface of Ocean

• Density and Salinity

  • Density in oceans is determined by temperature and salinity; warmer, less salty water is less dense and remains on the surface.

  • Salt distribution varies across oceans, affecting buoyancy and life – higher salinity generally increases buoyancy (e.g., the Dead Sea).

Chapter 6: Layers of Ocean

• Thermo-Haline Circulation

  • A crucial aspect of global ocean circulation, driven by density differences due to temperature and salinity.

  • Cold, salty water sinks in specific regions, contributing to deep ocean currents which play roles in heat and nutrient distribution.

Chapter 7: Conclusion

• Global Conveyor Belt

  • The process of cold, dense water sinking in the North Atlantic helps drive the global ocean conveyor belt, essential for heat transport.

  • Differential heat distribution influences global climate patterns, with implications for weather systems and climate stability.

• Impact of Ocean Heat Content

  • The ocean has absorbed over 90% of excess heat due to climate change, playing a significant role in regulating Earth’s climate and temperature stability.