Coastal Upwelling on the US West Coast Quiz
Ekman transport, nutrients, fog and temps (10 questions).
Coastal Upwelling on the US West Coast Quiz: Quick Study Notes
Coastal upwelling on the US West Coast is a fundamental oceanographic process with profound impacts on both marine and terrestrial environments. Driven by persistent northerly winds and the Coriolis effect, it brings cold, nutrient-rich water from the deep ocean to the surface, fueling one of the world’s most productive marine ecosystems. This phenomenon also influences regional climate, contributing to the famous California coastal fog and moderating temperatures.
Key Concepts
Surface water is pushed offshore (westward) by northerly winds, due to the Coriolis effect, leading to a deficit of surface water near the coast.
The offshore movement of surface water is replaced by cold, deep water rich in nitrates, phosphates, and silicates.
Cold upwelled waters cool the overlying air, leading to condensation and the frequent formation of dense coastal fog.
The presence of cold surface water moderates coastal air temperatures, resulting in milder summers and influencing local climate.
Key Takeaways
- **Driven by Wind and Coriolis:** Northerly winds and Earth’s rotation combine to drive offshore surface water movement.
- **Offshore Transport:** Ekman transport moves surface water approximately 90 degrees to the right of the wind direction (offshore on the US West Coast).
- **Nutrient-Rich Waters:** Upwelling brings vital nutrients (nitrates, phosphates, silicates) from the deep to the euphotic zone.
- **High Productivity:** These nutrients fuel massive phytoplankton blooms, supporting a highly productive marine food web.
- **Coastal Fog Source:** Cold upwelled water cools moist air, leading to widespread coastal fog, especially in summer.
- **Climate Moderation:** The cold ocean water significantly lowers coastal air temperatures, creating a milder, more temperate climate.
- **Ecological Impact:** Upwelling supports diverse ecosystems, including iconic species like redwoods (via fog drip) and vast fisheries.
Frequently Asked Questions
What is coastal upwelling on the US West Coast?
Coastal upwelling is an oceanographic process where cold, deep, nutrient-rich water rises to the ocean surface, replacing warmer surface water that has been pushed away from the coast.
How does Ekman transport contribute to upwelling?
On the US West Coast, persistent northerly winds, combined with the Coriolis effect, cause surface water to be transported offshore (to the west). This offshore movement creates a void near the coast, which is then filled by deeper water rising to the surface.
Why are upwelled waters so rich in nutrients?
Deep ocean waters are rich in dissolved inorganic nutrients (like nitrates, phosphates, and silicates) because they accumulate from the decomposition of organic matter that sinks from the surface. Without light for photosynthesis, these nutrients remain unconsumed at depth.
How does upwelling lead to coastal fog?
When the relatively warm, moist air from the land or ocean moves over the significantly colder upwelled surface waters, it cools rapidly to its dew point. This cooling causes water vapor to condense into tiny droplets, forming dense fog that then drifts onshore.
What impact does upwelling have on the climate of the US West Coast?
Upwelling introduces vast amounts of cold water to the surface, which significantly cools the coastal air temperatures, especially during summer. This leads to a mild, temperate climate along the immediate coast, often characterized by persistent fog and cooler conditions compared to inland areas.
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