Lecture 2: The stratified ocean Flashcards
What layer lies between the oceans surface water and deep water?
the pycnocline
pycnoclines create effective barriers to vertical mixing
Why is ocean stratification important?
It separates nutrients and cooler water which can have different effects
What does stronger stratification do to mixing?
Stronger stratification means less vertical mixing, which leads to more heat in the upper-ocean and can impact marine life
What three properties effect sea water density?
temperature, salinity and pressure
What are three ways water density can increase?
- Density increases with decreasing temperature
- Density increases with increasing salinity
- Density also increases with pressure (increasing pressure squeezes water into a smaller volume)
What is the equation for weight?
W = pVg
What is Archimede’s Principle?
An object submerged in a fluid will experience an upward buoyant force that is equal to the weight of fluid it displaces
What will happen if a parcel of seawater moves into a different density?
buoyancy forces will try to return it to its equilibrium depth, via convection
What is stable stratification?
Stable stratification occurs when each layer is less dense than the one below it. Buoyancy forces tend to preserve stable stratification.
What is a consequence of stable stratification?
internal waves that propagate horizontally along the pycnocline
What is unstable stratification and how is it corrected?
Unstable stratification occurs when a layer is denser than the one below it. Buoyancy forces trigger convection, to correct it
Does pressure act in one direction?
NO, pressure acts in ALL directions
What is the equation for hydrostatic pressure?
P= p-gz
z = thickness of water column
How do we calculate pressure for a stratified ocean?
By calculating the layers pressures separately and adding them together
