Coastal Geography, Oceanography Flashcards
Mixed layer
The upper part of the ocean that is in contact with the atmopshere that plays an important role in wind mixing and heat exchange. It is roughly 50m deep and is affected by seasonal variation
Which two main properties of the mixed layer are uniform
Temperature and salinity
Ocean currents
Masses of ocean water that flow from one place to another due to wind setup.
How does coriolis force influence ocean currents?
Currents deflect to the right in the Northern Hemisphere whilst deflecting to the left in the Southern Hemipshere
What is the process of Ekman transport
Water is deflected either right or left depending on the hemisphere. This movement is passed through the ocean column so that the ‘average’ net transport of water is at right angles to the initial wind direction
At what depth does Ekman transport occur
Shallow surface of the ocean: < 100m
Upwelling
The movement of cold, nutrient-rich water from the depths of the ocean to the mixed layer
Downwelling
The movement of warm, nutrient-poor water from the suface of the ocean to the coast
What do Southward winds near the coast do?
Southward winds along the coast cause upwelling, thus producing cold temperatures near the coast
What do Northward winds near the coast do?
Northward winds near the coast cause downwelling, thus producing warmer temperatures near the coast
Why are waters near the Equator nutrient rich?
Due to Coriolis force, downwelling causes warm, nutrient-poor water to flow away from the Equator in both the Northern and Southern Hemisphere
Subtropical gyre
Huge, circular surface currents cased by ocean currents being deflected right and left due to Coriolis force
What does Ekman transport do in subtropical gyres?
Water is piled in these gyres, slightly eleavting the water over a vast area
How do Western boundary currents influence subtropical gyres
In each subtropical gyre, Western boundary currents return warm water to the poles
How is the Gulf Stream an example of a Western boundary current
Water in the subtropical gyres is returned in strong, narrow currents along the Western boundaries of the Gulf
Why does the Antarctic circumpolar current keep warm water away from Antarctica?
The Antarctic circumpolar current is driven by strong Westerly winds that flow clockwise around the continent.
Why is the Antarctic circumpolar current significant?
It conects all of the oceans (Pacific, Atlantic, and Indian), and allows them to exchnage currents
What drives deep ocean circulation?
Deep ocean circulation is driven by differences in water densities
Thermohaline circulation
A type of ocean circulation that is driven by differences in temperature and salinity within the oceans’ strata
Why is thermohaline circulation important?
Thermohaline circulation is important because it brings oxygen to deep water (for plankton to perform photosynthesis) while also bringing nutrients to the surface. Additionally, it also regulates climate by driving warmer surface waters to the poles from the subtropics
What are the two main ocean currents around New Zealand?
The return flow of the Western boundary current and the Antarctic circumpolar current
Bathymetry
The seafloor (like topology for land)
What are the names of the two shallow parts of land surrounding New Zealand?
The Kermadec Trench (North) and the Campbell Plateau (South)
How does New Zealand’s bathymetry influence deep ocean currents?
The Western boundary current flows North along the Kermadec Trench while the Antarctic circumpolar current flows East along the Campbell Plateau
